Striped bass | Morone saxatilis
Striped bass info via Wikipedia:
Not evaluated (IUCN 3.1)
The striped bass (Morone saxatilis), also called Atlantic striped bass, striper, linesider, pimpfish, rock, or rockfish, is the state fish of Maryland, Rhode Island, South Carolina, and the state saltwater (marine) fish of New York, New Jersey, Virginia, and New Hampshire. They are also found in the Minas Basin and Gaspereau River in Nova Scotia, Canada and the Miramichi River and Saint John River in New Brunswick, Canada.
- Morphology and lifespan
- Environmental factors
- Life cycle
- Hybrids with other bass
- Fishing for striped bass
- Landlocked striped bass
- Other references
- External links
Morphology and lifespan
The striped bass is a typical member of the Moronidae family in shape, having a streamlined, silvery body marked with longitudinal dark stripes running from behind the gills to the base of the tail. The maximum scientifically recorded weight is 57 kg (125 lb). Common mature size is 120 cm (3.9 ft). Striped bass are believed to live for up to 30 years. The maximum length is 1.8 m (6 ft). The average size is about 67–100 cm (2.2-3.3 ft) and 4.5-14.5 kg (10-32 lb).
Striped bass are native to the Atlantic coastline of North America from the St. Lawrence River into the Gulf of Mexico to approximately Louisiana. They are anadromous fish that migrate between fresh and salt water. Spawning takes place in fresh water.
Introductions outside their natural range
Striped bass have been introduced to the Pacific Coast of North America and into many of the large reservoir impoundments across the United States by state game and fish commissions for the purposes of recreational fishing and as a predator to control populations of gizzard shad. These include: Elephant Butte Lake in New Mexico; Lake Ouachita, Lake Norman in North Carolina, Lake Norfork, Beaver Lake and Lake Hamilton in Arkansas; Lake Powell, Putnam Illinois (Lake Thunderbird) Lake Pleasant, and Lake Havasu in Arizona; Castaic Lake and Lake George in Florida, Pyramid Lake, Silverwood Lake, Diamond Valley Lake, Lewis Smith Lake in Alabama , Lake Cumberland in Kentucky , and Lake Murray in South Carolina; Lake Lanier in Georgia; Watts Bar Lake, Tennessee; and Lake Mead, Nevada; Lake Texoma, Lake Tawakoni, Lake Whitney, Possum Kingdom Lake, and Lake Buchanan in Texas; Raystown Lake in Pennsylvania; and in Virginia's Smith Mountain Lake and Leesville Lake.
The spawning success of striped bass has been studied in the San Francisco Bay-Delta water system, with a finding that high total dissolved solids (TDS) reduce spawning. At levels as low as 200 mg/l TDS, an observable diminution of spawning productivity occurs. They can be found in lakes, ponds, streams, and wetlands.
In the United States, the striped bass was designated as a protected game fish in 2007, and executive agencies were directed to use existing legal authorities to prohibit the sale of striped bass caught in federal waters in the Atlantic Ocean and Gulf of Mexico.
In Canada, the province of Quebec designated the striped bass population of the Saint Lawrence as extirpated in 1996. Analysis of available data implicated overfishing and dredging in the disappearance. In 2002, a successful reintroduction program was introduced.
Striped bass spawn in fresh water, and although they have been successfully adapted to freshwater habitat, they naturally spend their adult lives in saltwater (i.e., it is anadromous). Four important bodies of water with breeding stocks of striped bass are: Chesapeake Bay, Massachusetts Bay/Cape Cod, Hudson River and Delaware River. It is believed that many of the rivers and tributaries that emptied into the Atlantic, had at one time, breeding stock of striped bass. One of the largest breeding areas is the Chesapeake Bay, where populations from Chesapeake and Delaware bays have intermingled. The very few successful spawning populations of freshwater striped bass include Lake Texoma, the Colorado River and its reservoirs downstream from and including Lake Powell, and the Arkansas River, as well as Lake Marion (South Carolina) that retained a landlocked breeding population when the dam was built; other freshwater fisheries must be restocked with hatchery-produced fish annually. Stocking of striped bass was discontinued at Lake Mead in 1973 once natural reproduction was verified.
Hybrids with other bass
Striped bass have also been hybridized with white bass to produce hybrid striped bass also known as wiper, whiterock bass, sunshine bass, and Cherokee bass. These hybrids have been stocked in many freshwater areas across the US.
Fishing for striped bass
Striped bass are of significant value for sport fishing, and have been introduced to many waterways outside their natural range. A variety of angling methods are used, including trolling and surf casting with topwater lures a good pick for surf casting, as well as bait casting with live and deceased bait. Striped bass will take a number of live and fresh baits, including bunker, clams, eels, sandworms, herring, bloodworms, mackerel, and shad, with the last being an excellent bait for freshwater fishing.
The largest striped bass ever taken by angling was an 81.88-lb (37.14-kg) specimen taken from a boat in Long Island Sound, near the Outer Southwest Reef, off the coast of Westbrook, Connecticut. The all-tackle world record fish was taken by Gregory Myerson on the night of August 4, 2011. The fish took a drifted live eel bait, and fought for 20 minutes before being boated by Myerson. A second hook and leader was discovered in the fish's mouth when it was boated, indicating it had been previously hooked by another angler. The fish measured 54 in length and had a girth of 36 in. The International Game Fish Association declared Myerson's catch the new all-tackle world record striped bass on October 19, 2011. In addition to now holding the All-Tackle record, Meyerson’s catch also landed him the new IGFA men’s 37-kg (80-lb) line class record for striped bass, which previously stood at 70 lb. The previous all-tackle world record fish was a 78.5-lb (35.6-kg) specimen taken in Atlantic City, New Jersey on September 21, 1982 by Albert McReynolds, who fought the fish from the beach for 1:20 after it took his Rebel artificial lure. McReynolds' all-tackle world record stood for 29 years.
Recreational bag limits vary by state and province.
Landlocked striped bass
Striped bass are an anadromous fish, so their spawning ritual of traveling up rivers to spawn led some of them to become landlocked during lake dam constructions. The first area where they became landlocked was documented to be in the Santee-Cooper River during the construction of the two dams that impounded Lakes Moultrie and Marion, and because of this, the state game fish of South Carolina is the striped bass.
Recently, biologists came to believe that striped bass stayed in rivers for long periods of time, with some not returning to sea unless temperature changes forced migration. Once fishermen and biologists caught on to rising striped bass populations, many state natural resources departments started stocking striped bass in local lakes. Striped bass still continue the natural spawn run in freshwater lakes, traveling up river and blocked at the next dam, which is why they are landlocked. Landlocked stripers have a hard time reproducing naturally, and one of the few and most successful rivers they have been documented reproducing successfully is the Coosa River in Alabama and Georgia.
A 70.6-lb (32.0-kg) landlocked bass was caught in February 2013 by James Bramlett on the Warrior River in Alabama, a current world record. This fish had a length of 44 inches (112 cm) and a girth of 37.75 inches (96 cm).
One of the only landlocked striped bass populations in Canada is located in the Grand Lake, Nova Scotia. They migrate out in early April into the Shubencadie River to spawn. These bass also spawn in the Stewiacke River (a tributary of the Shubencadie ). The Shubencadie River system is one of five known spawning areas in Canada for striped bass, with the others being the St. Lawerence River, Miramichi River, Saint John River, Annapolis River and Shubencadie/Stewiacke Rivers. http://www.dfo-mpo.gc.ca/species-especes/species-especes/stripedbass-Fundy-barraye-eng.htm
The striped bass population declined to less than 5 million by 1982, but efforts by fishermen and management programs to rebuild the stock proved successful, and in 2007, there were nearly 56 million fish, including all ages. Recreational anglers and commercial fisherman caught an unprecedented 3.8 million fish in 2006. The management of the species includes size limits, commercial quotas, and biological reference points for the health of the species. The Atlantic States Marine Fisheries Commission states that striped bass are "not overfished and overfishing is not occurring."
- Froese, Rainer and Pauly, Daniel, eds. (2007). "Morone saxatilis" in FishBase. March 2007 version.
- National Audubon Society (May 2001). National Audubon Society Field Guide to North American Fishes. Knopf, Rev Sub edition (May 21, 2002). ISBN 0375412247.
- Striped Bass Management Plan retrieved on 10 June 2007.
- Pennsylvania State Fish & Boat Commission, Gallery of Pennsylvania Fishes, Chapter 21. Retrieved 10 June 2007.
- Indiana Fish and Wildlife, Evaluation of Striped Bass Stockings at Harden Reservoir. Retrieved 10 June 2007.
- Kaiser Engineers, California, Final Report to the State of California, San Francisco Bay-Delta Water Quality Control Program, State of California, Sacramento, CA (1969)
- "Executive Order 13449: Protection of Striped Bass and Red Drum Fish Populations". Office of the Federal Register. October 20, 2007. Retrieved October 24, 2007.
- "Reintroduction of the striped bass into the St. Lawrence" (2nd ed.). Minister of the Environment. 2008. Retrieved May 12, 2014.
- "Reproduction of striped bass - A historical first: spawning ground identified in Montmagny". Gouvernement du Québec, 2003-2012. September 1, 2011. Retrieved May 12, 2014.
- Chesapeake Bay Program, Striped Bass
- Wilde, G. R. and L.J. Paulson. 1989. Food habits of subadult striped bass in Lake Mead Arizona-Nevada. The Southwestern Naturalist 34(1) 118-123.
- Illinois Department of Natural Resources, Status of the Striped Bass/Hybrid Bass Bass Fishery March 2006 retrieved 10 June 2007.
- Pennsylvania State Fish & Boat Commission, Gallery of Pennsylvania Fishes, Chapter 21. Retrieved 10 June 2007.
- Greg Myerson's World Record Striper Official Website
- IGFA all-tackle world record striped bass
- New Jersey Division of Fish and Wildlife
- David DiBendetto, On The Run, An Angler's Journey Down the Striper Coast, page 195
- "History of Freshwater Striped Bass". Retrieved 2010-03-01.
- "Striped Bass in River Systems". Retrieved 2010-03-01.
- "Word Record Landlocked Bass". Retrieved 2013-05-21.
- "Atlantic States Marine Fisheries Commission: Striped Bass". Retrieved 2009-07-02.
- Atlantic striped bass NOAA FishWatch. Retrieved 5 November 2012.
Florida pompano | Trachinotus carolinus
Florida pompano info via Wikipedia:
The Florida pompano (Trachinotus carolinus) is a species of marine fish in the Trachinotus (pompano) genus of the Carangidae family. It has a compressed body and short snout; coloration varies from blue-greenish silver on the dorsal areas and silver to yellow on the body and fins. It can be found along the western coast of the Atlantic Ocean, depending on the season, and is popular for both sport and commercial fishing. Most Florida pompano caught weigh less than 3 lb (1.4 kg) and are less than 17 in (43 cm) long, though the largest individuals weigh 8–9 lb (3.6–4.1 kg) and reach lengths up to 26 in (66 cm).
Because it is fast-growing and desirable for food, the pompano is one of the many fish that is currently being farmed through aquaculture.
The different kinds of pompano include African, Cayenne, Florida and Irish. The Florida pompano (T. carolinus) is part of the jack family. It is very similar to the permit (Trachinotus falcatus). It has a deeply forked tail and is blue-greenish silver with yellow on the throat, belly, and pelvic and anal fins. The first dorsal fins are low, with about six separate spines. The first spine may be reabsorbed in a larger fish. The second lobes on the dorsal and anal fins have a lower anterior. There are 20-24 anal fin rays. It is a compressed fish with a deep body and a blunt snout.
Juvenile pompano grow between 0.8 and 1.9 in (20 and 48 mm) per month, depending on the population. Pompano grow quickly and attain a length of about 12 in (30 cm) and a weight of about 1 lb (0.45 kg) after the first year. The relationship between total length (L, in inches) and total weight (W, in pounds) for nearly all fish can be expressed by an equation of the form:
Invariably, b is close to 3.0 for all species, and c is a constant that varies among species. A weight-length relationship was determined for a sample of 1,984 Florida pompano collected along the Gulf Coast of Florida between 2000 and 2002. The fish sampled ranged in length from 79-481 mm (3.16-19.24 in). For this sample of Florida pompano, b = 2.9342 and c = 0.00076.
This relationship predicts that a 12-inch (300 mm) pompano will weigh about a pound. Most are less than three pounds when caught, though the largest pompano recorded have weighed 8-9 lb and were 23-25 in long.
Range and habitat
The adult Florida pompano is typically found in more saline areas and relatively warm waters (70-89°F), so it migrates northward in the summer, and toward the south in the fall. Despite its name, the range of the Florida pompano extends from Massachusetts to Brazil, but it is more common in areas near Florida. During the summer, it can be found near Sebastian, Cape Hatteras, and the Gulf of Mexico. It is more common near oil rigs, Palm Beach, and Hobe Sound during the winter. It can also be found near the Virgin Islands year round.
Its habitat is surf flats, and it tends to stay away from clear water regions, such as the Bahamas. Pompanos are very fast swimmers and live in schools. They are bottom feeders. They have very short teeth and feed on zoobenthos and small clams.
The pompano is a popular food fish. Chefs like it because the fillets are of even thickness, which aids in cooking. A popular dish created in New Orleans, called “pompano en papillote,” is wrapped in parchment paper with a white sauce of wine, shrimp, and crabmeat, and then steamed.
The pompano’s flesh is oily and looks white and opaque. Its diet yields a rich but mild flavor. Fresh fillets can cost $17 or more. Demand has encouraged the use of aquaculture to increase supply.
The Florida pompano is a popular choice for aquaculture because it is such a popular food and sport fish and is in high demand, and at the same time it has a fast growth rate, high dockside prices, and a tolerance for low-salinity waters. The typical market size of farm-raised pompano is 1 to 1.5 lb (0.45 to 0.68 kg).
The pompano supports an important commercial and recreational fishery. Florida pompano are commercially fished in all states on the East Coast from Virginia to Texas, with Florida producing over 90% of the annual harvest. Harvesting occurs mostly along Florida's western coast, with some harvesting on the eastern coast and in the Banana and Indian Rivers. Between 1994 and 2006, it commanded dockside prices of more than $3 per pound of whole fish weight.
Individually, Florida pompano are caught on light jigs and popping corks. They are very active on the line, testing light tackle beyond what their weight would suggest. They bite near oil rigs in the winter.
From 1997-2000, the fishing mortality rates increased sharply. However, an extensive study by the Florida Fish and Wildlife Commission concluded, as of 2005, the population of Florida pompano was healthy and the fishery was sustainable with current practices.
- Froese, Rainer and Pauly, Daniel, eds. (2006). "Trachinotus carolinus" in FishBase. April 2006 version.
- Smith, C. Lavett, National Audubon Society Field Guide to Tropical Marine Fishes of the Caribbean, the Gulf of Mexico, Florida, the Bahamas, and Bermuda. Chanticleer Press, 1997, ISBN 0-679-44601-X, color plate 268, p. 490
- R. O. Anderson and R. M. Neumann, Length, Weight, and Associated Structural Indices, in Fisheries Techniques, second edition, B.E. Murphy and D.W. Willis, eds., American Fisheries Society, 1996.
- Murphy, M.D., Muller, R.G., Guindon, K. A stock assessment for pompano, Trachinotus carolinus, in Florida waters through 2005. Report to the Florida Fish and Wildlife Conservation Commission, Division of Marine Fisheries Management. In-house report 2008-004, 2008.
- ESPN page on Florida pompano
- Smithsonian Marine Station page on Florida pompano
- Ristori, Al. The Saltwater Fish Identifier. New York: Mallard Press, 1992, ISBN 0-7924-5575-4, pp. 44
- rch%20and%20Development MOTE Marine Laboratory aquaculture of Florida pompano
- Southern Regional Aquacultural Center (Texas A&M) Species Profile on Florida pompano 2007
- Southern Regional Aquacultural Center (Texas A&M) Species Profile on Florida pompano 2007
- Smithsonian Marine Station page on Florida pompano
- 2002 article on age, growth and reproduction of Florida pompano
- ESPN page on Florida pompano
- Texas Parks and Wildlife page on Florida pompano
- MOTE marine laboratory research on Florida pompano aquaculture
- pompano recipes
Bull Shark | Carcharhinus leucas
Bull Shark info via Wikipedia:
(J. P. Müller and Henle, 1839)
|Range of bull shark|
The bull shark (Carcharhinus leucas), also known as the Zambezi shark or, unofficially, as Zambi in Africa and Nicaragua shark in Nicaragua, is a requiem shark commonly found worldwide in warm, shallow waters along coasts and in rivers. The bull shark is known for its aggressive nature, predilection for warm shallow water, and presence in brackish and freshwater systems including estuaries and rivers.
Bull sharks can thrive in both saltwater and freshwater and can travel far up rivers. They have even been known to travel as far up the Mississippi River as Illinois, although there have been few recorded freshwater attacks. They are probably responsible for the majority of near-shore shark attacks, including many attacks attributed to other species.
- Evolutionary Disconnect
- Anatomy and appearance
- Distribution and habitat
- See also
- Notes and references
- External links
The name "bull shark" comes from the shark's stocky shape, broad, flat snout, and aggressive, unpredictable behavior. In India, the bull shark may be confused with the Sundarbans or Ganges shark. In Africa, it is also commonly called the Zambezi River shark or just Zambi. Its wide range and diverse habitats result in many other local names, including Ganges River shark, Fitzroy Creek whaler, van Rooyen’s shark, Lake Nicaragua shark, river shark, freshwater whaler, estuary whaler, Swan River whaler, cub shark, and shovelnose shark.
The bull shark is a special case in evolutionary history. Some of its closest living relatives do not have the capabilities to osmoregulation. The bull shark’s genus, Carcharhinus, is shared by the sand bar shark that is not capable of osmoregulation. Although, bull sharks share the same family, Carcharhinidae, with the little known river sharks as well as the same subclass, Elasmobranchii. This allows for some evolutionary predictions of where the bull shark first originated. Is it a river shark turned to the sea? Or a sea shark turned towards the river? The bull shark just has very much in common with river sharks, glyphis, and its own genus of Carcharhinus, but the evolutionary question still stands, where exactly did this shark come from and when? Much more evolutionary evidence is needed to draw a sound conclusion of the bull sharks phylogeny.
Anatomy and appearance
Bull sharks are large and stout, with females being larger than males. The bull shark can be up to 81 cm (2.66 ft) in length at birth. Adult female bull sharks average 2.4 m (7.9 ft) long and typically weigh 130 kg (290 lb), whereas the slightly smaller adult male averages 2.25 m (7.4 ft) and 95 kg (209 lb). While a maximum size of 3.5 m (11 ft) is commonly reported, there is a questionable record of a female specimen of exactly 4 m (13 ft). The maximum recorded weight of a bull shark was 315 kg (694 lb) but may be larger. Bull sharks are wider and heavier than other requiem sharks of comparable length, and are grey on top and white below. The second dorsal fin is smaller than the first. The bull shark's caudal fin is longer and lower than that of the larger sharks, and it has a small snout, and lacks an interdorsal ridge.
Bull sharks have a bite force of up to 600 kilograms (1,300 lb), pound for pound the highest among all investigated cartilaginous fishes.
Distribution and habitat
The bull shark is commonly found worldwide in coastal areas of warm oceans, in rivers and lakes, and occasionally salt and freshwater streams if they are deep enough. It is found to a depth of 150 metres (490 ft), but does not usually swim deeper than 30 metres (98 ft). In the Atlantic, it is found from Massachusetts to southern Brazil, and from Morocco to Angola. In the Indian Ocean, it is found from South Africa to Kenya, India, and Vietnam to Australia.
Populations of bull sharks are also found in several major rivers, with more than 500 bull sharks thought to be living in the Brisbane River. One was reportedly seen swimming the flooded streets of Brisbane, Queensland, Australia, during the Queensland floods of late 2010/early 2011. Several were sighted in one of the main streets of Goodna, Queensland, shortly after the peak of the January 2011, floods. A large bull shark was caught in the canals of Scarborough, just north of Brisbane within Moreton Bay. There are greater numbers still in the canals of the Gold Coast, also in Queensland. In the Pacific Ocean, it can be found from Baja California to Ecuador. The shark has traveled 4,000 kilometres (2,500 mi) up the Amazon River to Iquitos in Peru. and north Bolivia  It also lives in fresh water Lake Nicaragua, in the Ganges and Brahmaputra rivers of West Bengal and Assam in eastern India and adjoining Bangladesh. It can live in water with a high salt content as in St. Lucia Estuary in South Africa. The bull shark is generally prolific in the warm coastal waters and estuarine systems of the Mozambique Channel and southward, including Kwa-Zulu Natal and Mozambique. The species has a distinct preference for warm currents.
After Hurricane Katrina, many bull sharks were sighted in Lake Pontchartrain. Bull sharks have occasionally gone up the Mississippi River as far upstream as Alton, Illinois. They have also been found in the Potomac River in Maryland. A golf course lake in Queensland, Australia is the home to several bull sharks. They are believed to have become trapped following a flood in the 1990s. The golf course has capitalized on the novelty and now hosts a monthly tournament called the "Shark Lake Challenge."
The bull shark is the best known of 43 species of elasmobranch in ten genera and four families to have been reported in fresh water. Other species that enter rivers include the stingrays (Dasyatidae, Potamotrygonidae and others) and sawfish (Pristidae). Some skates (Rajidae), smooth dogfishes (Triakidae), and sandbar sharks (Carcharhinus plumbeus) regularly enter estuaries. The bull shark is a fish that is diadromous, meaning they can swim between saltwater and freshwater with ease. These fish also fall under the category of euryhaline fish. Euryhaline refers to an organism that is able to adapt to a wide range of salinities. The bull shark is one of the only cartilaginous fishes that have been reported in freshwater systems. Many of the euryhaline species are bony fish such as salmon and tilapia and do not qualify as fish that are closely related to bull sharks due to their physiological makeup. Evolutionary assumptions can be made to help explain this sort of evolutionary disconnect; one being that the bull shark encountered a population bottleneck that occurred during the last ice age. This bottleneck may have separated the bull shark from the rest of the elasmobranchii subclass and favored the genes for an osmoregulatory system. Elasmobranchs' ability to enter fresh water is limited because their blood is normally at least as salty (in terms of osmotic strength) as seawater through the accumulation of urea and trimethylamine oxide, but bull sharks living in fresh water show a significantly reduced concentration of urea within their blood. Despite this, the solute composition (i.e. osmolarity) of a bull shark in freshwater is still much higher than that of the external environment. This results in a large influx of water across the gills due to osmosis and loss of sodium and chloride from the shark's body. However, bull sharks in freshwater possess several organs with which to maintain appropriate salt and water balance; these are the rectal gland, kidneys, liver and gills. All elasmobranchs have a rectal gland which functions in the excretion of excess salts accumulated as a consequence of living in seawater. Bull sharks in freshwater environments decrease the salt-excretory activity of the rectal gland, thereby conserving sodium and chloride. The kidneys produce large amounts of dilute urine, but also play an important role in the active reabsorption of solutes into the blood. The gills of bull sharks are likely to be involved in the uptake of sodium and chloride from the surrounding freshwater, whereas urea is produced in the liver as required with changes in environmental salinity.
Initially, scientists thought the sharks in Lake Nicaragua belonged to an endemic species, the Lake Nicaragua shark (Carcharhinus nicaraguensis). In 1961, following specimens comparisons, taxonomists synonymized them. They can jump along the rapids of the San Juan River (which connects Lake Nicaragua and the Caribbean Sea), almost like salmon. Bull sharks tagged inside the lake have later been caught in the open ocean (and vice versa), with some taking as little as seven to eleven days to complete the journey.
Bull sharks are able to regulate themselves to live in either fresh water or salt water. It is possible for the bull shark to live in fresh water for its entire life, but it has been observed that this does not happen for certain reasons, mostly due to reproduction. Young bull sharks will leave the brackish water in which they are born and move out into the sea in order to breed with bull sharks of the other sex. While theoretically, it may be possible for bull sharks to live in purely freshwater, it was observed that the bull sharks that were being experimented on had died within four years. The stomach was opened and all that was found were 2 small fishes that were unidentifiable. The cause of death could have been starvation since the primary food source for bull sharks resides in salt water.
The bull shark is known to be able to live in both saltwater and freshwater. It was found in a research experiment that, the majority of the time, the bull sharks were found to be at the mouth of an estuary. The water salinity was tested every month to determine if the difference in salinity is what drove bull sharks into the river. It was found that the bull shark stayed at the mouth of the river independent of the salinity of the water. The driving factor for a bull shark to be in freshwater or saltwater is its age; as the bull shark ages the tolerance for very low or high salinity increases. It was found that the majority of the newborn or very young bull sharks were found in the freshwater area, whereas the much older bull sharks were found to be in the saltwater, as they had developed a much better tolerance for the salinity. This is one of the reasons why adult bull sharks will travel into the river (in order to reproduce). This is thought to be a physiological strategy to help with juvenile survival rates and a way to increase overall fitness of bull sharks. The newborns are not born with a high tolerance for high salinity, so they are born in freshwater and stay there until they are able to travel out.
The bull shark's diet consists mainly of bony fish and small sharks, including other bull sharks, but can also include turtles, birds, dolphins, terrestrial mammals, crustaceans, echinoderms, and stingrays. They hunt in murky waters because it is harder for the prey to see the shark coming. Bull sharks have been known to use the bump-and-bite technique to attack their prey. After the first initial contact the bull shark continues to bite and tackle its prey until they are unable to flee. Bull sharks are believed to have attacked hippopotamuses in Africa's Zambezi River, based on bite marks on the hippos' feet.
The bull shark is known to be a solitary hunter, although there are brief moments in which the bull sharks will team up with another bull shark in order to make it easier to hunt and to trick prey.
Sharks are known to be opportunistic feeders, and the bull shark is no exception to this, as it is part of the Carcharhinus family of sharks. Normally, sharks eat in short bursts, and when food is scarce, sharks digest for a much longer period of time in order to avoid starvation. As part of their survival mechanism, bull sharks will regurgitate the food in their stomachs in order to escape from a predator. This is a distraction tactic, if the predator moves to eat the regurgitated food the bull shark can use the opportunity to escape.
Bull sharks mate during late summer and early autumn, often in the brackish water of river mouths. After gestating for 12 months, a bull shark may give birth to four to ten live young. They are viviparous; they are born live and free-swimming. The young are about 70 cm (27.6 in) at birth and take 10 years to reach maturity. Coastal lagoons, river mouths, and other low-salinity estuaries are common nursery habitats.
175 cm to 235 cm seems to be the size of a fully matured female bull shark that produce viable eggs for fertilization. The courting routine between bull sharks has not been observed in detail as of yet. It is speculated that the male bites the females on the tail until they turn upside down and they male can copulate at that point. At some points, the harassment of the male can become violent. It is not uncommon to see scratches and other marks on a mature female from the mating ritual.
Bull sharks have an unusual migratory pattern in comparison to other sharks. They are found in rivers all over the world. They have the ability to go from seawater and freshwater. They give birth in the freshwater of rivers. The young bull sharks are free from predators while they grow up in the river before they go out to the sea in order to find mates.
The ability to be able to survive in both freshwater and saltwater also gives another benefit that has been driven by evolution. Because the majority of sharks are only able to survive in saltwater, the bull shark has evolved to have their offspring in the freshwater where other sharks cannot enter. The freshwater acts as a protective area where the young are able to grow and mature without the threat of larger sharks preying on the younger bull sharks. This is an explanation for the behavior that is observed from the bull sharks as to why there would be any reason for the adult bull shark to ever travel into a freshwater area despite being able to tolerate the high salinity of marine water.
Bull sharks are born alive in freshwater. The size range of a litter for a female bull shark is around 1 to 13 pups. The average time span for a female bull shark to be pregnant is around 10 to 11 months. The male bull shark is able to begin reproducing around the age of 15 years while the female cannot begin reproducing until the age of 18 years. Unlike most sharks though, the bull shark does not rear its young like other sharks, the young bull sharks are born into flat, protected areas. Freshwater presents a natural defense against most larger predators, and the flat land is an added defense as most large predators will not swim in shallow areas. This increases their chance of survival since the parents do not rear the young in the traditional manner. This is also the reason why there is a high mortality rate in young bull sharks. Since the parents do not rear and protect the young, any predator that is able to attack a young bull shark is easily able to kill and eat the young bull shark without much resistance.
Interactions with humans
Since bull sharks often dwell in very shallow waters, they may be more dangerous to humans than any other species of shark, and along with the tiger shark, oceanic whitetip and great white shark, are among the four shark species most likely to attack humans.
One or several bull sharks may have been responsible for the Jersey Shore shark attacks of 1916, which were the inspiration for Peter Benchley's novel Jaws. The speculation of bull sharks possibly being responsible is based on some attacks occurring in brackish and freshwater.
The bull shark is responsible for attacks around the Sydney Harbour inlets. Most of these attacks were previously attributed to great white sharks. In India, bull sharks swim up the Ganges River and have attacked people. Many of these attacks have been attributed to the Ganges shark, Glyphis gangeticus, a critically endangered river shark species that is probably the only other shark in India able to survive in fresh water, although the sand tiger shark was also blamed during the 1960s and 1970s.
The bull shark prefers coastal water which is less than 100 feet in depth. This is mostly due to their feeding patterns since they prefer murky waters. This is also a problem since this gives the most interaction with humans. It is known that bull sharks inhabit areas off the coast of Florida, and there have been reports of bull sharks getting close enough to the coast to attack humans since the bull shark is a territorial animal.
Behavioral studies have confirmed that sharks can take visual cues in order to discriminate between different objects. The bull shark is able to discriminate between colors of mesh netting that is present underwater. It was found that bull sharks tended to avoid mesh netting of bright colors rather than colors that blended in with the water. Bright yellow mesh netting was found to be easily avoided when it was placed in the path of the bull shark. This was found to be the reason that sharks are attracted to bright yellow survival gear rather than ones that were painted black. This is very important because it gives an insight into how bull sharks are able to pick up certain visual keys underwater that might give them an advantage when seeking out certain prey.
In 2008, researchers tagged and recorded the movements of young bull sharks in the Caloosahatchee River estuary. Specifically, they were testing to find out what determined the movement of the young bull sharks. It was found that the young bull sharks synchronously moved downriver when the environmental conditions changed. This large movement of young bull sharks were found to be moving as a response rather than other external factors such as predators. An interesting find was that the movement was directly related to the bull shark conserving energy for itself. One way the bull shark is able to conserve energy is that when the tidal flow changes, the bull shark uses the tidal flow in order to conserve energy as it moves downriver. Another way for the bull shark to conserve energy is to decrease the amount of energy needed to osmoregulate the surrounding environment.
Bull sharks are apex predators and seldom have to fear being attacked by other animals. Humans are their biggest threat. Larger sharks, such as the tiger shark and great white shark, may attack them. There have been stories documented in the media of saltwater crocodiles preying on young bull sharks in the rivers and estuaries of Northern Australia.
Notes and references
- Simpfendorfer, C. & Burgess, G.H. (2005). "Carcharhinus leucas". IUCN Red List of Threatened Species. Version 2011.1. International Union for Conservation of Nature. Retrieved 18 August 2011.
- Sharks In Illinois. In-Fisherman (16 July 2012). Retrieved on 30 November 2013.
- "Bull shark". Florida Museum of Natural History. Retrieved 8 September 2006.
- "Bull shark". National Geographic. Retrieved 3 April 2011.
- "Biology of Sharks and Rays". ReefQuest Centre for Shark Research. Retrieved 19 August 2010.
- McGrouther, Mark (12 May 2010). "Bull Shark, Carcharhinus leucas Valenciennes, 1839 – Australian Museum". Australian Museum. Retrieved 19 August 2010.
- Allen, Thomas B. (1999). The Shark Almanac. New York: The Lyons Press. ISBN 1-55821-582-4.
- McAuley, R. B.; Simpfendorfer, C. A.; Hyndes, G. A. and Lenanton, R. C. J. (2007). "Distribution and reproductive biology of the sandbar shark, Carcharhinus plumbeus (Nardo), in Western Australian waters". Mar. Freshwater Res. 58 (1): 116–126. doi:10.1071/MF05234. "The proportion of mature males with running spermatozoa increased from 7.1% in October to 79 and 80% in January and March, respectively, suggesting that mating activity peaks during late summer and early autumn." Cite uses deprecated parameters (help)
- Fowler, S., Reed, T., Dipper, F. (1997). Elasmobranch biodiversity, conservation, and management: Proceedings of the international seminar and workshop. Gland Switzerland: IUCN.
- "Shark Species; Bull Sharks". Shark Diver Magazine 17: 34. 2003.
- "The Rosenstiel School of Marine & Atmospheric Science".
- "9 Biggest Sharks Ever Caught". Total Pro Sports.com.
- Habegger, M. L.; Motta, P. J.; Huber, D. R.; Dean, M. N. (2012). "Feeding biomechanics and theoretical calculations of bite force in bull sharks (Carcharhinus leucas) during ontogeny". Zoology. doi:10.1016/j.zool.2012.04.007. ; for a popular summary, see Walker, Matt (12 October 2012). "Bull sharks have strongest bite of all shark species". BBC News. Retrieved 12 October 2012.
- Crist, Rick. "Carcharhinus leucas". University of Michigan Museum of Zoology, Animal Diversity Web. Retrieved 8 September 2006.
- "Queensland rebuilding 'huge task'". BBC News. 12 January 2011.
- Bull sharks seen in flooded streets | Offbeat | Weird News, Odd and Freaky Stories in Northern Rivers | Clarence Valley Daily Examiner. Dailyexaminer.com.au (14 January 2011). Retrieved on 4 May 2012.
- Berrett, Nick (14 November 2008). "Canal shark shock". Redcliffe & Bayside Herald. Quest Community Newspapers. Retrieved 26 March 2009.
- Shark Gallery. Bull shark (Carcharhinus leucas). sharks-med.netfirms.com
- High number of sharks reported in Lake Pontchartrain. wwltv.com. 16 September 2006
- "Sharks in Illinois". In-Fisherman. Retrieved 26 July 2010.
- 8-Foot Shark Caught In Potomac River. Nbcwashington.com. Retrieved on 4 May 2012.
- Zauzmer, Julie (22 August 2013). "Man catches 2 bull sharks in Potomac". Washington Post.
- "Shark-Infested Australian Golf Course Believed to Be World's First". Fox News. October 11, 2011.
- Compagno, Leonard I.V. and Cook, Sid F. (March 1995). "Freshwater elasmobranchs; a questionable future". Florida Museum of Natural History Ichthyology Department. Retrieved 27 April 2011.
- Heupel, Michelle R.; Colin A. Simpfendorfer (2008). "Movement and distribution of young bull sharks Carcharhinus leucas in a variable estuarine environment". Aqutic Biology 1: 277–289. doi:10.3354/ab00030.
- Tillett B., Meekan, M., Field, I., Thornburn, D., Ovenden, J. (2012). "Evidence for reproductive philopatry in the bull shark Carcharhinus leucas". Journal of Fish Biology 80: 2140–2158.
- Pillans, R.D.; Franklin, C.E. (2004). "Plasma osmolyte concentrations and rectal gland mass of bull sharks Carcharhinus leucas, captured along a salinity gradient.". Comparative Biochemistry and Physiology A: Molecular and Integrative Physiology 138 (3): 363–371. doi:10.1016/j.cbpb.2004.05.006. PMID 15313492.
- Pillans, R.D.; Good, J.P., Anderson, W.G., Hazon, N and Franklin, C.E. (2005). "Freshwater to seawater acclimation of juvenile bull sharks (Carcharhinus leucas): plasma osmolytes and Na+/K+-ATPase activity in gill, rectal gland, kidney and intestine". Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology 175 (1): 37–44. doi:10.1007/s00360-004-0460-2. PMID 15565307. Cite uses deprecated parameters (help)
- Reilly, B.D.; Cramp, R.L., Wilson, J.M., Campbell, H.A and Franklin, C.E. (2011). "Branchial osmoregulation in the euryhaline bull shark, Carcharhinus leucas: a molecular analysis of ion transporters". The Journal of Experimental Biology 214 (17): 2883–2895. doi:10.1242/jeb.058156. PMID 21832131. Cite uses deprecated parameters (help)
- Anderson, W.G.; Good, J.P., Pillans, R.D., Hazon, N and Franklin, C.E. (2005). "Hepatic urea biosynthesis in the euryhaline elasmobranch Carcharhinus leucas". Journal of Experimental Zoology Part A: Comparative Experimental Biology 303A (10): 917–921. doi:10.1002/jez.a.199. PMID 16161010. Cite uses deprecated parameters (help)
- Fresh Waters: Unexpected Haunts. elasmo-research.org. Accessed 6 April 2008.
- Montoya, Rafael Vasquez; Thorson, Thomas B. (1982). "The bull shark and largetooth sawfish in Lake Bayano, a tropical man-made impoundment in Panama". Env. Biol. Fish 7 (4): 341–347. doi:10.1007/BF00005568.
- Kindersley, Dorling (2001) in Animal, David Burnie and Don E. Wilson (eds.) London & New York: Smithsonian Institution, ISBN 0789477645.
- Snelson, Franklin F; Mulligan, Timothy J; Williams, Sherry E. (1 January 1984). "Food Habits, Occurrence, and Population Structure of the Bull Shark, Carcharhinus Leucas, in Florida Coastal Lagoons". Bulletin of Marine Science 1: 71–80.
- Motta, Philip J; Wilga, Cheryl D. (2001). "Advances in the study of feeding behaviors, mechanisms, and mechanics or sharks". Environmental Biology of Fishes 60 (60): 131–156. doi:10.1023/A:1007649900712.
- International Masters Publishers. Wildlife Explorer. Group 4, cards 33 and 4. ISBN 1-886614-77-6.
- Bull Sharks, Carcharhinus leucas. Marinebio.org (14 January 2013). Retrieved on 30 November 2013.
- Life of Bull Shark | Life of Sea. Life-sea.blogspot.com (15 November 2011).
- Tuma, Robert E (1976). Investigations of the ichthyofauna of Nicaraguan lakes. American Society of Ichthyologists and Herpetologists.
- Jenson, Norman H (1976). "Investigation of the Icthyofauna of Nicaraguan Lakes". American Society of Ichthyologists and Herpetologists.
- Bres, M (1993). "The Behaviour of Sharks". Reviews in Fish Biology and Fisheries 3 (2): 133–159. doi:10.1007/BF00045229.
- Heupel, Michelle R.; Carlson, John K. and Simpfendorfer, Colin A. (14 May 2007). "Shark nursery areas: concepts, definitoin characterization and assumptions". Marine: Ecology Progress Series 337: 289–297. doi:10.3354/meps337287. Cite uses deprecated parameters (help)
- Pacific Shark Research Center » Featured Elasmobranch – Bull Shark. Psrc.mlml.calstate.edu (16 February 2009). Retrieved on 30 November 2013.
- Fact Sheet: Bull Sharks. Sharkinfo.ch (15 October 1999). Retrieved on 30 November 2013.
- Bull Shark – Animal Facts and Information. Bioexpedition.com. Retrieved on 30 November 2013.
- Handwerk, Brian. "Great Whites May Be Taking the Rap for Bull Shark Attacks". National Geographic News. Retrieved 1 February 2007.
- Quinn, Ben (15 March 2009). "Shark attacks bring panic to Sydney's shore". The Guardian (London). Retrieved November 2009.
- Frantz, Vickie (18 July 2011). "Bull Sharks Attacks Comonly in Warm, Shallow Waters". accuweather.
- Bres, M. (1993). "The behaviour of sharks". Reviews in Fish Bviology and Fisheries 3 (2): 133–159. doi:10.1007/BF00045229.
- Ortega, Lori A.; Heupel, Michelle R.; van Beynen, Philip and Motta, Philip J. (2009). "Movement patterns and water quality preferences of juvenile bull sharks (Carcharhinus lecuas) in a Florida estuary". Evionrmen Biol Fish 84 (4): 361–373. doi:10.1007/s10641-009-9442-2. Cite uses deprecated parameters (help)
- "No Bull: Saltwater Crocodile Eats Shark". UnderwaterTimes.com. 13 August 2007. Retrieved 15 June 2008.
|Wikimedia Commons has media related to Carcharhinus leucas.|
|Wikispecies has information related to: Carcharhinus leucas|
Longnose Gar | Lepisosteus osseus
Longnose Gar info on Wikipedia:
|Longnose gar at the New England Aquarium.|
The longnose gar, Lepisosteus osseus, is a primitive ray-finned fish of the gar family. It is also known as the needlenose gar. L. osseus is found along the east coast of North and Central America in freshwater lakes and as far west as Kansas and Texas and southern New Mexico. The gar have been present in North America for about 100 million years.
Fossils have been found in Africa, Asia, Europe, North America, and South America dating back 100 million years. Currently, longnose gar are found in Central America, Cuba, North America, and the Isles of Pines. Longnose gar are frequently found in fresh water in the eastern half of the United States, but some gar were found in salinities up to 31 ppt. Their microhabitats consist of areas near downed trees, stone outcrops, and vegetation. The decline of their population is mainly due to human manipulation of aquatic systems.
The most common prey of the longnose gar is clupeids (herrings and shads), as well as cyprinids and fundulids; they usually feed at night. Their main competitors are other gar of their own species, as well as other types of gar. Larger gar have been known to feed on smaller gar, as well. Longnose gar were a main source of food for Native Americans and early colonists. The first settlers at Jamestown, Virginia, dined on this fish through their harsh early years. Today, gar is more of sport fish, but their meat is surprisingly tasty. Predation is not a problem on adult longnose gar, but they are vulnerable to other gar predation when they are young, including adult longnose gar. L. osseus is carnivorous; for example, their diet consists of sunfish, catfish, and crayfish in their Texas range. Sexual maturity for males is reached between three and four years of age, and females at six years of age. Sex ratios are in favor of the males in the early life stages until about 10 years, then switches in favor of females. Females hold an average clutch size of about 27,000 eggs. Their eggs are very toxic to terrestrial vertebrates, but other piscivorous fish could tolerate the toxins.
Longnose gar have an average lifespan of 15–20 years with a maximum reported age of 39. This long lifespan allows the female to sexually mature around six years old. Males mature sexually as soon as two years of age. Longnose gars are sexually dimorphic; the females are larger than the males in body length, weight, and fin length. They generally have a clutch size close to 30,000, depending on the weight to length ratio of the females; larger females bear larger clutch sizes. They spawn in temperatures close to 20°C in late April and early July. Eggs have a toxic, adhesive coating to help them stick to substrates, and they are deposited onto stones in shallow water, rocky shelves, vegetation, or smallmouth bass nests. Their hatch time is seven to 9 days; young gar stay in vegetation during the first summer of life. Longnose gar reach an average length of 28-48 in (0.71-1.2 m) with a maximum length of about 6 ft (1.8 m) and 55 lb (25 kg) in weight.
Currently, no management of this species is being conducted, nor is it federally listed as endangered, although some states have reported it as threatened (South Dakota, Delaware, and Pennsylvania). In the early 1900s, longnose gar were considered as destructive and worthless predators. Many people feared them based on their spooky appearance of a long mouth filled with teeth and armor-like scales, as well as their diet of anything that would fit in their mouths. Soon after this characterization, gar population reduction methods were established. L. osseus has been reported as a threatened species (South Dakota, Delaware, and Pennsylvania). Their declining populations are due to overfishing, habitat loss, dams, road construction, pollution, and other human-caused destruction of the aquatic systems. Overfishing is more of a trophy fish than for food; people find their meat to have a mild but tasty flavor. Because of their long lifespans and older sexual maturity age, factors affecting their reproduction is an issue in preserving them. Overfishing is a large issue for this fish, especially when the fish have not reached sexual maturity due to the female not peaking sexual maturity until about six years of age.
- McGrath, P.E., E. J. Hilton. 2011. Sexual dimorphism in longnose gar Lepisosteus osseus. Journal of Fish Biology 80(2)335-345.
- Wiley, E. O. 1976. The phylogeny and biogeography of fossil and recent gars (Actinopterygii: Lepisosteidae). Miscellaneous Publication, University of Kansas, Museum of Natural History 64
- Uhler, P. R. & O. Lugger. 1876. List of fishes of Maryland. Report of the Commissioners of Fisheries of Maryland, to the General Assembly
- Suttkus, R. D. 1963. Order Lepisostei. In: Fishes of the Western North Atlantic, Memoir 1, Part Three, of the Sears Foundation for Marine Research (H. B. Bigelow, C. M. Cohen, G. W. Mead, D. Merriman, Y. H. Olsen, W. C. Schroeder, L. P. Schultz, and J. Tee-Van, eds.), pp. 61-88. New Haven, CT: Yale University.
- Haase, B. L. 1969. An ecological life history of the longnose gar, Lepisosteus osseus (Linnaeus), in Lake Mendota and in several other lakes of southern Wisconsin. Dissertation, The University of Wisconsin - Madison, Madison, Wisconsin.
- Bonham, Kelshaw. 1941. Food of gars in Texas. Transactions of the American Fisheries Society 70(1):356-362.
- Straube, B. and N. Luccketti. 1996. Jamestown rediscovery 1995 interim report. November 2006. The Association for the Preservation of Virginia Antiquities, 55 p.
- Bonham, Kelshaw. 1941. Food of gars in Texas. Transactions of the American Fisheries Society 70(1):356-362.
- Netsh, Lt. Norval F., Arthur Witt Jr. 1962. Contributions to the Life History of the Longnose Gar (Lepisosteus osseus) in Missouri. Transactions of the American Fisheris Society 91(3):251-262.
- Netsh, Lt. Norval F., Arthur Witt Jr. 1962. Contributions to the Life History of the Longnose Gar (Lepisosteus osseus) in Missouri. Transactions of the American Fisheris Society 91(3):251-262.
- Beard, J. 1889. On the early development of Lepidosteus osseus. Proceedings of the Royal Society of London 46:108-118.
- Haase, B. L. 1969. An ecological life history of the longnose gar, Lepisosteus osseus (Linnaeus), in Lake Mendota and in several other lakes of southern Wisconsin. Dissertation, The University of Wisconsin - Madison, Madison, Wisconsin.
- Johnson, Brian L., Douglas B. Noltie. 1997. Demography, Growth, and Reproductive Allocation in Stream-Spawning Longnose Gar. Transactions of the American Fisheries Society 126:438-466
- Alfaro, Roberto Mendoza, et al. 2008. Gar biology and culture: status and prospects. Aquaculture Research 39:748-763
- Alfaro, Roberto Mendoza, et al. 2008. Gar biology and culture: status and prospects. Aquaculture Research 39:748-763
- Spitzer, Mark. Season of the Gar: Adventures in Pursuit of America's Most Misunderstood Fish. U of Arkansas Press, 2010.
|Wikimedia Commons has media related to Lepisosteus osseus.|
Lesser Siren | Siren intermedia
This print was created by applying india ink on the siren and pressing it onto paper. This is a rarely seen critter in streams of the southeastern US and northern Mexico. It is a tricky one to print as the exterior ‘gills’, seen in a red paint behind it’s long head, are very small. Likewise, it has two small appendages that are difficult to capture in the printed image.
Lesser Siren info via Wikipedia:
The lesser siren (Siren intermedia) is a species of aquatic salamander native to the eastern United States and northern Mexico. They are referred by numerous common names, including two-legged eel, dwarf siren, and mud eel. The specific epithet intermedia denotes their intermediate size, between the greater siren, Siren lacertina, and the dwarf sirens, Pseudobranchus spp.
The lesser siren is nocturnal, spending its days hidden in the debris and mud at the bottom of slow-moving bodies of water. They feed primarily on aquatic invertebrates, including various kinds of worms, snails, and crustaceans. They will also eat the tadpoles and eggs of other amphibians.
Reproduction occurs in the spring, with eggs being laid in shallow depressions at the bottom of calm areas of water, usually surrounded by vegetation. Though little is known about their courtship, it is believed to be quite violent, as many specimens collected have scarring from healed bite marks from other sirens. About 12-300 eggs are laid at a time, and several clutches may be laid over the course of the year. Hatchlings are only about 0.4 in (1.1 cm) in length, but grow quickly. Maturity is reached in three to four years.
The lesser siren is vocal, unlike most salamanders, and will emit a series of clicks when it approaches others of its species, or a short screeching sound if handled.
If the habitat dries up during the summer, lesser sirens are capable of excreting a substance from their skin which protects them from dehydrating, and enables them to stay buried in dry mud for months until the water returns. Their small legs enable them to move on dry land for short periods of time.
The lesser siren is found in the United States, primarily from Virginia to Florida, and west to Texas (ranging into northeastern Mexico as far as Veracruz), and north to Illinois, Indiana and Michigan.
Sources disagree on the number of subspecies within S. intermedia; most agree there are at least two, an eastern and a western variety. Many sources also include a third subspecies, the Rio Grande lesser siren, S. i. texana, but researchers disagree whether the Rio Grande variety belongs as a lesser siren, within S. intermedia, or as a greater siren, within S. lacertina, and some others even consider it to be its own species, as S. texana.
- Eastern lesser siren, S. i. intermedia (Goin, 1942)
- Western lesser siren, S. i. nettingi (Goin, 1942)
- Rio Grande lesser siren, S. i. texana (Goin, 1957)
The lesser siren is quite common through most of its range, but rarely seen due to its secretive nature. Like almost all species of amphibian, their numbers are believed to be declining due to general reductions in water quality caused by agricultural pesticide and fertilizer runoff. They are frequently collected and used as bait for fishing. The species is believed to be extirpated from Michigan, and the S. i. texana subspecies is listed as a threatened species in Texas.
- "IUCN Red List of Threatened Species". Retrieved 2008-08-24.
- Animal Diversity Web: Siren intermedia
- INHS Reptile & Amphibian Collection: Siren intermedia - Lesser Siren
|Wikispecies has information related to: Siren intermedia|
Common Snapping Turtle | Chelydra serpentina
|Common snapping turtle|
|Female searching for nest site|
|Range map of C. serpentina|
The common snapping turtle (Chelydra serpentina) is a large freshwater turtle of the family Chelydridae. Its natural range extends from southeastern Canada, southwest to the edge of the Rocky Mountains, as far east as Nova Scotia and Florida. This species and the larger alligator snapping turtle are the only two species in this family found in North America (though the common snapping turtle, as its name implies, is much more widespread).
The common snapping turtle is noted for its belligerent disposition when out of the water, its powerful beak-like jaws, and highly mobile head and neck (hence the specific name serpentina, meaning "snake-like"). In some areas, they are hunted very heavily for their meat, a popular ingredient in turtle soup. Snapping turtles have a life-history strategy characterized by high and variable mortality of embryos and hatchlings, delayed sexual maturity, extended adult longevity, and iteroparity (repeated reproductive events) with low reproductive success per reproductive event. Females, and presumably also males, in more northern populations mature later (at 15-20 years) and at a larger size than in more southern populations (about 12 years). Lifespan in the wild is poorly known, but long-term mark-recapture data from Algonquin Park in Ontario, Canada suggest a maximum age over 100 years.
- Anatomy and morphology
- Ecology and life history
- Systematics and taxonomy
- Invasive species
- In politics
- External links
Anatomy and morphology
C. serpentina has a rugged, muscular build with ridged carapaces (though ridges tend to be more pronounced in younger individuals). The carapace (upper shell) length in adulthood may be nearly 50 cm (20 in), though 25–47 cm (9.8–18.5 in), is more common.C. serpentina usually weighs 4.5–16 kg (9.9–35.3 lb). Any specimen above the aforementioned weights are exceptional, but the heaviest wild specimen caught reportedly weighed 34 kg (75 lb). Snapping turtles kept in captivity can be quite overweight due to overfeeding and have weighed as much as 39 kg (86 lb). In the northern part of its range, the common snapping turtle is often the heaviest native freshwater turtle.
Ecology and life history
Common habitats are shallow ponds or streams. Some may inhabit brackish environments, such as estuaries. Common snapping turtles sometimes bask—though rarely observed—by floating on the surface with only their carapaces exposed, though in the northern parts of their range, they also readily bask on fallen logs in early spring. In shallow waters, common snapping turtles may lie beneath a muddy bottom with only their heads exposed, stretching their long necks to the surface for an occasional breath (their nostrils are positioned on the very tip of the snout, effectively functioning as snorkels). Snapping turtles consume both plant and animal matter, and are important aquatic scavengers, but they are also active hunters that prey on anything they can swallow, including many invertebrates, fish, frogs, reptiles (including snakes and smaller turtles), unwary birds, and small mammals.
Common snapping turtles have few predators when older, but eggs are subject to predation by crows, mink, skunks, foxes, and raccoons. As hatchlings and juveniles predators include herons, bitterns, crows, hawks, bullfrogs, large fish, and snakes.
These turtles travel extensively over land to reach new habitats or to lay eggs. Pollution, habitat destruction, food scarcity, overcrowding, and other factors drive snappers to move; it is quite common to find them traveling far from the nearest water source. This species mates from April through November, with their peak laying season in June and July. The female can hold sperm for several seasons, using it as necessary. Females travel over land to find sandy soil in which to lay their eggs, often some distance from the water. After digging a hole, the female typically deposits 25 to 80 eggs each year, guiding them into the nest with her hind feet and covering them with sand for incubation and protection. Incubation time is temperature-dependent, ranging from 9 to 18 weeks. In cooler climates, hatchlings overwinter in the nest. The common snapping turtle is remarkably cold-tolerant; radiotelemetry studies have shown some individuals do not hibernate, but remain active under the ice during the winter. Although designated as "least concern" on the IUCN redlist, the species has been designated in the Canadian part of its range as "Special Concern" due to its life history being sensitive to disruption by anthropogenic activity.
Systematics and taxonomy
Currently, no subspecies of the common snapping turtle are recognized. The former subspecies osceola is now[when?] considered a synonym of serpentina, while the other former subspecies Chelydra rossignonii and Chelydra acutirostris are both recognized as full species.
Snapping turtles have fierce dispositions; but when encountered in the water, they usually slip quietly away from any disturbance. Snapping turtles have evolved the ability to snap because, unlike other turtles, they are too large to hide in their shells when confronted. Snapping is their defense mechanism. Snapping turtles will bite humans if threatened, but as a last resort. The turtle will try to scare off threats by hissing before it bites.
The common snapping turtle is an aquatic ambush hunter, capturing its prey with its beak-like jaws.
The common snapping turtle is not an ideal pet. Its neck is very flexible, and a wild turtle can bite its handler even if picked up by the sides of its shell. A wild common snapping turtle will make a hissing sound when it is threatened or encountered; however, when in the water and unprovoked, they are fairly docile toward humans.
It is a common misconception that common snapping turtles may be safely picked up by the tail with no harm to the animal; in fact, this has a high chance of injuring the turtle, especially the tail itself and the vertebral column. Lifting the turtle with the hands is difficult and dangerous. Snappers can stretch their necks back across their own carapace and to their hind feet on either side to bite. Also, their claws are sharp and capable of inflicting significant lacerations. When they feel stressed, they release a musky odor from behind their legs.
It may be tempting to rescue a snapping turtle found in a road by getting it to bite a stick and then dragging it out of immediate danger. This action can, however, severely scrape the legs and underside of the turtle and allow for deadly infections in the wounds. The safest way to pick up a common snapping turtle is by grasping the carapace above the back legs. There is a large gap above the back legs that allows for easy grasping of the carapace and keeps hands safe from both the beak and claws of the turtle.
In Italy in recent years, large mature adult C. serpentina turtles have been taken from bodies of water throughout the country. They were most probably introduced by the unwise release of pets. In March 2011, an individual weighing 20 kg (44 lb) was captured in a canal near Rome; another individual was captured near Rome in September 2012.
The common snapping turtle was the central feature of a famous American political cartoon. Published in 1808 in protest at the Jeffersonian Embargo Act of 1807, the cartoon depicted a snapping turtle, jaws locked fiercely to an American trader who was attempting to carry a barrel of goods onto a British ship. The trader was seen whimsically uttering the words "Oh! this cursed Ograbme" ("embargo" spelled backwards). This piece is widely considered a pioneering work within the genre of the modern political cartoon.
In 2006, the snapping turtle was declared the state reptile of New York by a sweeping vote of the New York Legislature after being popularly chosen by the state's public elementary school children.
- Chelydra serpentina, IUCN
- C.H. Ernst (2008). "Systematics, Taxonomy, and Geographic Distribution of the Snapping Turtles, Family Chelydridae". In A.C. Styermark, M.S. Finkler, R.J. Brooks. Biology of the Snapping Turtle (Chelydra serpentina). Johns Hopkins University Press. pp. 5–13.
- http://publications.gc.ca/collections/collection_2009/ec/CW69-14-565-2009E.pdf. Missing or empty
- Kindersley, Dorling (2001,2005). Animal. New York City: DK Publishing. ISBN 0-7894-7764-5. Check date values in:
- Virginia Herpetological Society: Eastern Snapping Turtle Chelydra serpentina serpentina
- US Army Corps of Engineers, Engineer Research and Development Center, Environmental Laboratory: Common Snapping Turtle (Chelydra serpentina)
- COSEWIC. "Species Profile - Snapping Turtle". Species At Risk Public Registry. Government of Canada. Retrieved 24 February 2012.
- Rhodin, Anders G.J.; van Dijk, Peter Paul; Inverson, John B.; Shaffer, H. Bradley (2010-12-14). "Turtles of the world, 2010 update: Annotated checklist of taxonomy, synonymy, distribution and conservation status". Chelonian Research Monographs 5: 000.xx. doi:10.3854/crm.5.000.checklist.v3.2010. ISBN 0965354091. Archived from the original on 2010-12-15.
- van Dijk, P.P., J Lee, J., Calderón Mandujano, R., Flores-Villela, O., Lopez-Luna, M.A. & Vogt, R.C. (2007). Chelydra rossignoni. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 2009-05-04.
- Chelydra, Reptile Database
- Snapping Turtle, Encyclopedia.com
- Common Snapping Turtle, Nature.ca
- Indiviglio, Frank (2008-06-24). "Handling Snapping Turtles, Chelydra serpentina, and Other Large Turtles". That Reptile Blog. That Pet Place. Retrieved 2008-07-20.
- Fang Anning (方安宁), "“小庭院”养殖龟鳖大有赚头" (Small-scale turtle farming may be very profitable). Zuojiang Daily (左江日报) (with photo)
- Una "azzanatrice" catturata fuori Roma. March 17, 2011. Corriere della Sera. Milan.
- Medina, Jennifer (2006-06-23). "A Few Things Lawmakers Can Agree On". N.Y./Region (New York Times). Retrieved 2008-07-20.
|Wikispecies has information related to: Chelydra serpentina|
|Wikimedia Commons has media related to Chelydra serpentina.|
- The Snapping Turtle Page - www.chelydra.org
- Snapping Turtle - Chelydra serpentina Species account from the Iowa Reptile and Amphibian Field Guide
- Common Snapping Turtle, Natural Resources Canada
- Video: How to Help a Snapping Turtle Cross A Road from the Toronto Zoo
Smallmouth Buffalo| Ictiobus bubalus
Smallmouth Buffalo info on Wikipedia:
||This article includes a list of references, related reading or external links, but its sources remain unclear because it lacks inline citations. Please improve this article by introducing more precise citations. (May 2012)|
|The distribution of I. bubalus in the United States|
The smallmouth buffalo (Ictiobus bubalus, from the Greek for "bull-fish" and "buffalo") is a Cypriniformes fish species found in the major tributaries and surrounding waters of the Mississippi River in the United States as well as some other water systems where it has been introduced. It is a stocky fish like its relatives the bigmouth buffalo (Ictiobus cyprinellus) and the black buffalo (Ictiobus niger), although the smallmouth buffalo's mouth is located ventrally like other Catostomidae species while the bigmouth buffalo's mouth is terminal and opens forward, and the smallmouth buffalo's eyes are significantly larger than those of the black buffalo. These three species are superficially similar to the common carp (Cyprinus carpio), but all lack the characteristic barbels.
The coloration of smallmouth buffalo ranges from shades of gray to brown and coppery green dorsally and pale yellow to white ventrally. Fin colors match the portion of the body they attach to and are generally darker towards the tips. They are characteristically stocky, having a hump that rises up from where the operculum sits. Pectoral fins protrude ventrally like the anal fins, the caudal fin has even lobes, and the dorsal fin protrudes from the top of the hump to a blunt point then shortens and runs the remaining length of the body to the base of the tail. Average adults reach a length of around 40–60 cm (16–24 in) with some specimens reaching as much as 90 cm (35 in).
The smallmouth buffalo is a hardy fish that frequents clear, moderate to fast-moving streams but has been occasionally known in some lakes and ponds. If prefers waters with dense aquatic vegetation and a silty bottom. It has a high tolerance for hard water and can survive in waters with pH ranges of 6.5–8.5.
The smallmouth buffalo's diet is primarily that of a detritivore, using its ventral sucker mouth to pick up vegetation and other organic matter from the bottom of its habitat, often scraping algae off of rocks. It is also quite the invertivore, consuming zooplankton, insect larvae, mollusk larvae and small crustaceans.
Spawning usually takes place in spring and summer with more specific timeframes depending on the location of the population. Migration is negligible. Spawning often occurs in shallower sections of streams where the egg can adhere to vegetation and gravel to keep from flowing away. Each female can lay tens of thousands to hundreds of thousands of eggs at a time depending on her size, so no parental care is applied and the eggs hatch in one or two weeks. The young hide in aquatic vegetation to avoid predators. The average lifespan of a smallmouth buffalo is nine to eighteen years with males reaching sexual maturity in four to five years and females at around six years.
Although considered by many to be a rough fish, smallmouth buffalo is the most common commercially sold freshwater fish in the United States. The species is highly valued by some as a human food source and the fish meal is common in animal feed. They are relatively quick and easy to raise in commercial farm ponds. Anglers seeking to hook a smallmouth buffalo have found success with doughballs and corn on hooks.
Blue Sucker | Cycleptus elongatus
Color is variable, from light steel-gray to almost jet black in the spring. The fish is streamlined, with a pointed head and a subterminal mouth. The small head suggests in profile that of a horse. Early records indicate that this fish once reached weights of over 40 pounds (18 kg), although 15 pounds (6.8 kg) is quite rare today. Average lengths are 2 feet (0.61 m), the maximum being 0.93 metres (3 ft 1 in).
Huge migrations of these fast, powerful fish once migrated throughout the Mississippi River basin, and spring harvests of blue sucker were a staple food for early pioneers. Blue suckers are very rare today, thought to be due to the segmentation of habitat caused by the thousands of dams which have been built in the last century. Blues frequent the thalweg of large river systems, in heavy current.
- Gimenez Dixon (1996). Cycleptus elongatus. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006.
- Froese, Rainer and Pauly, Daniel, eds. (2005). "Cycleptus elongatus" in FishBase. November 2005 version.
- NatureServe - Cycleptus elongatus
- Fishes of Minnesota - Blue sucker
- roughfish.com - Blue sucker
- Rines, George Edwin, ed. (1920). "Blackhorse". Encyclopedia Americana.
American Alligator | Alligator mississippiensis
Temporal range: Pleistocene - present
(Daudin, 1802 [originally Crocodilus])
|American Alligator range map|
The American alligator (Alligator mississippiensis), sometimes referred to colloquially as a gator or common alligator, is a large crocodilian reptile endemic to the southeastern United States. It is one of two living species in the genus Alligator within the family Alligatoridae; it is larger than the other extant alligator species, the Chinese alligator. Adult male American alligators measure 3.4 to 4.6 m (11 to 15 ft) in length, and can weigh 453 kg (999 lb). Females are smaller, measuring around 3 m (9.8 ft). The American alligator inhabits freshwater wetlands, such as marshes and cypress swamps from Texas to North Carolina. It is distinguished from the sympatric American crocodile by its broader snout, with overlapping jaws and darker coloration, and is less tolerant of saltwater but more tolerant of cooler climates than the American crocodile, which is found only in tropical climates.
Alligators are apex predators and consume fish, amphibians, reptiles, birds, and mammals. Hatchlings feed mostly on invertebrates. They play an important role as ecosystem engineers in wetland ecosystems through the creation of alligator holes, which provide both wet and dry habitats for other organisms. Throughout the year, but especially during the breeding season, alligators bellow to declare territory and locate suitable mates. Male alligators use infrasound to attract females. Eggs are laid in a nest of vegetation, sticks, leaves, and mud in a sheltered spot in or near the water. Young are born with yellow bands around their bodies and are protected by their mother for up to one year.
The American alligator is listed as Least Concern by the International Union for Conservation of Nature. Historically, hunting has decimated their population, and the American alligator was listed as an endangered species by the Endangered Species Act of 1973. Subsequent conservation efforts have allowed their numbers to increase and the species was removed from the list in 1987. Alligators are now harvested for their skins and meat. The species is the official state reptile of three states: Florida, Louisiana, and Mississippi.
- Taxonomy and phylogeny
- Distribution and habitat
- Ecology and behavior
- Conservation status
- Relationships with humans
- See also
- External links
Taxonomy and phylogeny
The American alligator was first classified by French zoologist François Marie Daudin as Crocodilus mississipiensis in 1801. In 1807 Georges Cuvier created the genus Alligator; the American alligator shares this genus with the Chinese alligator. They are grouped in the family Alligatoridae with the caimans. The superfamily Alligatoroidea includes all crocodilians (fossil and extant) that are more closely related to the American alligator than to either the Nile crocodile or the gharial.
Members of this superfamily first arose in the late Cretaceous. Leidyosuchus of Alberta is the earliest known genus. Fossil alligatoroids have been found throughout Eurasia as land bridges across both the North Atlantic and the Bering Strait have connected North America to Eurasia during the Cretaceous, Paleogene, and Neogene periods. Alligators and caimans split in North America during the late Cretaceous and the latter reached South America by the Paleogene, before the closure of the Isthmus of Panama during the Neogene period. The Chinese alligator likely descended from a lineage that crossed the Bering land bridge during the Neogene. The modern American alligator is well represented in the fossil record of the Pleistocene. The alligator's full mitochondrial genome was sequenced in the 1990s and it suggests the animal evolved at a rate similar to mammals and greater than birds and other cold-blooded vertebrates.
Wild alligators range from long and slender to short and robust, possibly due to variations in factors such as growth rate, diet, and climate. Alligators have broad snouts, especially in captive individuals. When the jaws are closed, the edges of the upper jaws cover the lower teeth which fit into the jaws' depressions. Like the spectacled caiman, this species has a bony nasal ridge, though it is less prominent. The teeth number from 74–80. Dorsally, adult alligators may be olive, brown, gray, or black in color, while their undersides are cream-colored.
Some alligators are missing an inhibited gene for melanin, which makes them albino. These alligators are extremely rare and almost impossible to find in the wild. They could survive only in captivity, as they are very vulnerable to the sun and predators.
The American alligator is a fairly large species of crocodilian. As in all crocodilians, as opposed to many mammals where size eventually dimishes with old age, healthy alligators continue to grow throughout their lives and the oldest specimens are the largest. Very old, large male alligators reach an expected maximum size of 4.6 m (15 ft) in length, weighing up to 453 kg (999 lb), while females grow to a maximum of 3 m (9.8 ft). On rare occasions, a large, old male may grow to an even greater length. During the 19th and 20th centuries, larger males reaching 5 to 6 m (16 to 20 ft) have been reported. The largest reported individual size was a male killed in 1890 on Marsh Island, Louisiana, and reportedly measured at 5.8 m (19 ft) in length, but no voucher specimen was available, since the alligator was left on a muddy bank after having been measured due to having been too massive to relocate. If the size of this animal were correct, it would have weighed around 1,000 kg (2,200 lb). The largest alligator shot in Florida was 5.31 m (17.4 ft), as reported by the Everglades National Park.
However, American alligators do not normally reach such extreme sizes. In mature males, size averages around 3.4 m (11 ft) in length, weighing slightly in excess of 227 kg (500 lb), while in smaller females, the mature size averages 2.6 m (8.5 ft), weighing slightly more than 91 kg (201 lb). While noticeably sexual dimorphic in size, the sexual dimorphism of this species is relatively modest amongst crocodilians. In the saltwater crocodile, for example, the females are only slightly larger at average (2.8 m (9.2 ft) in the crocodile, 2.6 m (8.5 ft) in the alligator) than female American alligators, but the mature males, at 4.3 to 5.2 m (14 to 17 ft) on average as opposed to 2.7 to 4 m (8.9 to 13.1 ft) expected in mature male alligators, are considerably bigger than male American alligators and at median are nearly twice as long as and at least four times as heavy as the female crocodiles of the same species. Given that female alligators have relatively higher survival rates at an early age and a large percentage of given populations are comprised by immature or young breeding alligators, relatively few large mature males of the expected length of 3.4 m (11 ft) or more are typically seen. Weight varies considerably depending on length, age, health, season and available food sources. Similar to many other reptiles than range expansively into temperate zones, American alligators from the northern end of their range, such as southern Arkansas, Alabama, and northern North Carolina, tend to grow to smaller sizes. The largest alligator caught in Alabama was 4.5 m (15 ft) in length, weighing 459 kg (1,012 lb). 
In Arkansas a man killed an alligator that was 4.03 m (13.2 ft) and 626 kg (1,380 lb).
When on land, the alligator moves either by sprawling or walking, the latter involving the reptile lifting its belly off the ground. The sprawling of alligators and other crocodilians is not identical to the sprawling of salamanders and lizards, being similar to walking. Thus, the two forms of territorial locomotion can be termed the "low walk" and the "high walk". Unlike most other land vertebrates, alligators increase their speed through the distal rather than proximal ends of their limbs. In the water, alligators swim like fish; moving their pelvic regions and tails from side to side. American alligators held the record as having the strongest laboratory-measured bite of any living animal, measured at up to 9,452 newtons (2,125 lbf). It should be noted that this experiment had not been, at the time of the paper published, replicated in any other crocodilians, and the same laboratory was able to measure a greater bite force in saltwater crocodiles; notwithstanding this very high biting force, the muscles opening the alligator's jaw are quite weak, and the jaws can be held closed by hand or tape when an alligator is captured. During respiration, air flow is unidirectional, looping through the lungs during inhalation and exhalation; the alligator's abdominal muscles can alter the position of the lungs within the torso, thus shifting the center of buoyancy, which allows the alligator to dive, rise, and roll within the water.
Distribution and habitat
American alligators are found in the wild in the southeastern United States, from Great Dismal Swamp in Virginia and North Carolina, south to Everglades National Park in Florida, and west to the southern tip of Texas. They are found in North Carolina, South Carolina, Georgia, Florida, Louisiana, Alabama, Mississippi, Arkansas, Texas, and Oklahoma. They inhabit swamps, streams, rivers, ponds, and lakes. Females and juveniles are also found in Carolina Bays and other seasonal wetlands. While they prefer fresh water, alligators sometimes enter brackish water, but they are less tolerant of salt water than crocodiles, as the salt glands on their tongues do not function. One study of alligators in north-central Florida found the males preferred open lake water during the spring, while females used both swampy and open water areas. During summer, males still preferred open water, while females stuck to the swamps to construct their nests and lay their eggs. Both sexes may den underneath banks or clumps of trees during the winter.
American alligators are less vulnerable to cold than American crocodiles. Unlike the crocodile, which would immediately succumb to the cold and drown in water of 45 °F (7.2 °C), an alligator can survive in such temperatures for some time without any signs of discomfort. This adaptiveness is thought to be the reason why American alligators spread farther north than the American crocodile. In fact, the American alligator is found farther from the equator and is more equipped to deal with cooler conditions than any other crocodilian. When the water begins to freeze, alligators stick their snouts though the surface which allows them to breathe above the ice.
Ecology and behavior
Alligators modify wetland habitats, most dramatically in flat areas such as the Everglades, by constructing small ponds known as alligator holes. This behavior has qualified the American alligator to be considered a keystone species. Alligator holes retain water during the dry season and provide a refuge for aquatic organisms. Aquatic organisms that survive the dry season by seeking refuge in alligator holes are a source of future populations. The construction of nests along the periphery of alligator holes, as well as a buildup of soils during the excavation process, provide drier areas for other reptiles to nest and a place for plants that are not tolerant of inundation to colonize. Alligator holes are oases during the Everglades dry season, so are consequently important foraging sites for other organisms. In the limestone depressions of cypress swamps, alligator holes tend to be large and deep, while those in marl prairies and rocky glades are usually small and shallow, and those in peat depressions of ridge and slough wetlands are more variable.
Alligators play an important role in the restoration of the Everglades as biological indicators of restoration success. Alligators are highly sensitive to changes in the hydrology, salinity, and productivity of their ecosystems; all are factors that are expected to change with Everglades restoration. Alligators also may control the long-term vegetation dynamics in wetlands by reducing the population of small mammals, particularly nutria, which may otherwise overgraze marsh vegetation. In this way, the vital ecological service they provide may be important in reducing rates of coastal wetland losses in Louisiana. They may provide a protection service for water birds nesting on islands in freshwater wetlands. Alligators prevent predatory mammals from reaching island-based rookeries and in return eat spilled food and birds that fall from their nests. Wading birds appear to be attracted to areas with alligators and have been known to nest at heavily trafficked tourist attractions with large numbers of alligators, such as the St. Augustine Alligator Farm in St. Augustine, Florida. In addition to basking on shore, American alligators can and will climb trees to bask in if no shoreline is available. However, this is not often seen as the alligators will retreat back into the water by jumping from their perch.
Hunting and diet
The American alligator is considered an apex predator throughout its range. They are opportunists and their diet is determined largely by both the size and age of the alligator and the size and availability of prey. Most alligators will eat a wide variety of animals, including invertebrates, fish, birds, turtles, snakes, amphibians, and mammals. Hatchlings mostly feed on invertebrates such as insects, insect larvae, snails, spiders, and worms. As they grow, alligators gradually move on to larger prey. Once an alligator reaches adulthood, any animal living in the water or coming to the water to drink is potential prey, due to the size and power of the alligator. However, most animals captured by alligators are considerably smaller than the alligator itself. Stomach contents show, among native mammals, muskrats and raccoons are some of the most commonly eaten species. In Louisiana, where introduced nutria are common, they are perhaps the most regular prey for adult alligators, although only larger adult alligators commonly eat this species.
Other animals may occasionally be eaten, even large deer or feral wild boars, but these are not normally part of the diet. Occasionally, domestic animals, including dogs, cats, and calves, are taken as available, but are secondary to wild and feral prey.Water birds, such as herons and egrets, storks, and waterfowl, are taken when possible. Occasionally, unwary adult birds are grabbed and eaten by alligators, but most predation on bird species occur with unsteady fledgling birds in late summer as the prey of alligators, as fledgling birds attempt to make their first flights near the water's edge. Other prey, including snakes, lizards, and various invertebrates, are eaten occasionally by adults.
Fish and other aquatic prey taken in the water or at the water's edge form the major part of alligator's diet and may be eaten at any time of the day or night. Adult alligators also spend considerable time hunting on land, up to 50 m (170 ft) from water, ambushing terrestrial animals on trailsides and road shoulders. Usually, terrestrial hunting occurs on nights with warm temperatures. When hunting terrestrial prey, alligators may also ambush them from the edge of the water by grabbing them and pulling the prey into the water, the preferred method of predation of larger crocodiles. The teeth of the alligator are designed to grip prey, but can not rip or chew flesh like teeth of some other predators (such as canids and felids). The alligator is capable of biting though a turtle's shell or a moderately sized mammal bone.
Alligators often eat prey that would seem unusual for a crocodilian. Alligators rarely prey on adult deer, but will do so when fish and smaller prey levels go down. Rarely, alligators have been observed killing and eating bobcats, but such events are uncommon and have little effect on bobcat populations. Alligator predation on Florida panthers is rare, but has been documented. Such incidents usually involve a panther trying to cross a waterway or coming down to a swamp or river to get a drink. The American alligator is the only known natural predator of the panther. Alligator predation on black bears has also been recorded, although it is unknown if the bears taken were adults, as adult bears are powerful enough to successfully fend off an alligator attack. Although alligators have been listed as predators of manatees, very little evidence exists of such predation, even on calves.
In 2013, alligators and other crocodilians were reported to also eat fruit. Such behavior has been witnessed, as well as documented from stomach contents, with the alligators eating such fruit as wild grapes, elderberries, and citrus fruits directly from the trees. The discovery of this unexpected part of the alligator diet further reveals that alligators may be responsible for spreading seeds from the fruit it digests across its habitat.
American alligators have been documented using lures to hunt prey such as birds. This means they are among the first reptiles recorded to use tools. By balancing sticks and branches on their heads, American alligators are able to lure birds looking for suitable nesting material to kill and consume. This strategy, which is shared by the mugger crocodile, is particularly effective during the nesting season, in which birds are more likely to gather appropriate nesting materials.
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Crocodilians are the most vocal of all reptiles and have a variety of different calls depending on the age, size, and sex of the animal. The American alligator can perform specific vocalizations to declare territory, signal distress, threaten competitors, and locate suitable mates. Juvenile alligators can perform a high-pitched hatchling call (a trait common to many crocodilian species' hatchling young) to alert their mothers when they are ready to emerge from the nest. Juveniles also make a distress call to alert their mothers if they are being threatened. Although alligators have no vocal cords, both males and females bellow loudly to attract mates and declare territory by sucking air into their lungs and blowing it out in intermittent, deep-toned roars. The bellowing of the American alligator is distinct from the loud roaring of most crocodilians, and is considered unique. Male alligators are known to use infrasound during mating bellows. Bellowing is performed in a "head oblique, tail arched" posture. Infrasonic waves from a bellowing male alligator can cause the surface of the water directly over and to either side of its back to literally "sprinkle" in what is commonly called the "water dance". Large bellowing "choruses" of alligators during the breeding season are commonly initiated by females and perpetuated by males. Observers of large bellowing choruses have noted they are often felt more than they are heard due to the intense infrasound emitted by males. Alligators bellow in B flat, and bellowing choruses can be induced by tuba players, sonic booms, and large aircraft. In addition to bellowing, alligators can growl, hiss, or cough to threaten others and declare territory.
The breeding season begins in the spring. On spring nights, alligators gather in large numbers for group courtship, the so-called "alligator dances". The female builds a nest of vegetation, sticks, leaves, and mud in a sheltered spot in or near the water. After she lays her 20 to 50 white eggs, about the size of a goose egg, she covers them with more vegetation, which heats as it decays, helping to keep the eggs warm. This differs from Nile crocodiles, which lay their eggs in pits.
The temperature at which alligator eggs develop determines their sex (see temperature-dependent sex determination). Those eggs which are hatched at a temperature of 34 °C (93 °F) or more become males, while those at a temperature of 30 °C (86 °F) or lower become female. The nests built on levees are warmer and thus produce males, while the cooler nests of wet marsh produce females. The female remains near the nest throughout the 65-day incubation period, protecting it from intruders. When the young begin to hatch, the mother quickly digs them out and carries them to the water in her mouth, as some other crocodilian species are known to do.
The young are tiny replicas of adult alligators with a series of yellow bands around their bodies that serve as camouflage. Hatchlings gather into pods and are guarded by their mother and keep in contact with her through vocalizations. Young alligators eat small fish, frogs, crayfish, and insects. They are preyed on by large fish, birds, raccoons, and adult alligators. Mother alligators eventually become more aggressive towards their young, which encourages them to disperse. Young alligators grow 3–8 in (7.6–20.3 cm) a year and reach adulthood at 6 ft (1.8 m). An alligator can live up to 50 years.
Interactions with exotic species
Nutria were introduced into coastal marshes from South America in the mid-1900s, and their population has since exploded into the millions. They cause serious damage to coastal marshes and may dig burrows in levees. Hence, Louisiana has had a bounty to try to reduce nutria numbers. Large alligators, however, feed heavily on nutria, so alligators may not only control nutria populations in Louisiana, but also prevent them spreading east into the Everglades. Since hunting and trapping preferentially take the large alligators that are the most important in eating nutria, some changes in harvesting may be needed to capitalize on their ability to control nutria.
Recently, a population of non-native Burmese pythons has become established in Everglades National Park. While events of predation by Burmese pythons on alligators and vice versa have been observed, no evidence of a net negative effect has been seen on alligator populations.
Historically, hunting and habitat loss have decimated alligator populations throughout their range, and whether the species would survive was in doubt. In 1967, the alligator was listed as an endangered species (under a law that was the precursor Endangered Species Act of 1973), since it was believed to be in danger of extinction throughout all or a significant portion of its range.
Both the United States Fish and Wildlife Service (USFWS) and state wildlife agencies in the South contributed to the American alligator's recovery. Protection under the Endangered Species Act allowed the species to recuperate in many areas where it had been depleted. States began monitoring their alligator populations to ensure that they would continue to grow. In 1987, the USFWS removed the animal from the endangered species list, as it was considered to be fully recovered. The USFWS still regulates the legal trade in alligators and their products to protect still endangered crocodilians that may be passed off as alligators during trafficking.
Relationships with humans
Attacks on humans
Alligators are capable of killing humans, but are generally wary enough not to see them as a potential prey. Mistaken identity leading to an attack is always possible, especially in or near cloudy waters. Alligators are often less aggressive towards humans than large crocodile species, a few of which (mainly the Nile and saltwater crocodile) may prey on humans with some regularity. Alligator bites are serious injuries due to the reptile's sheer bite force and risk of infection. Even with medical treatment, an alligator bite may still result in a fatal infection.
As human populations increase, and as they build houses in low-lying areas or fish or hunt near water, incidents are inevitable where alligators threaten, or at least appear to threaten, human life. Since 1948, 275 documented attacks on humans in Florida (about five incidents per year) have been reported, of which at least 17 resulted in death. Only nine fatal attacks occurred in the US throughout the 1970s–1990s, but alligators killed 12 people between 2001 and 2007. In May 2006, alligators killed three Floridians in less than a week.
Since the late 1880s, alligator wrestling has been a source of entertainment for some. Created by the Miccosukee and Seminole tribes prior to the arrival of Europeans, this tourism tradition continues to persist despite criticism from animal rights activists.
Today, alligator farming is a large, growing industry in Georgia, Florida, Texas, and Louisiana. These states produce a combined annual total of some 45,000 alligator hides. Alligator hides bring good prices and hides in the 6 to 7-ft range have sold for $300 each. The market for alligator meat is growing, and about 300,000 pounds (140,000 kg) of meat are produced annually. According to the Florida Department of Agriculture and Consumer Services, raw alligator meat contains roughly 200 Calories (840 kJ) per 3-oz (85-g) serving, of which 27 Calories (130 kJ) come from fat.
"Gators" has been the nickname of the University of Florida's sports teams since 1911. In that year, a printer made a spur-of-the-moment decision to print an alligator emblem on a shipment of the school's football pennants. The mascot stuck, perhaps because the team captain's nickname was Gator.
The Gator Bowl is a college football game held in Jacksonville annually since 1946, with Gator Bowl Stadium hosting the event until the 1993 edition. The Gatornationals is a NHRA drag race held at the Gainesville Raceway in Gainesville since 1970.
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|Wikimedia Commons has media related to Alligator mississippiensis.|
- Crocodilian Online
- Photo exhibit on alligators in Florida; from State Archives of Florida
- Why the Gulf Coast needs more big alligators
- U.S. Fishery and Wildlife Service – alligator bellows and hisses
- American Alligator at care-sheet.com (WikiPets)
Atlantic Needlefish Gyotaku by Inked Animal
Info via Wikipedia:
Strongylura marina, known commonly as the Atlantic needlefish, is a common bottom-water needlefish species common in marinas and other areas with minimal current. Its extremely long jaw and body set this fish apart from other predators.
Strongylura marina is found along western Atlantic coastal waters from Maine to southern Brazil, including areas along the coast of the Gulf of Mexico and Caribbean. Atlantic needlefish are not restricted to ocean waters; they can be found in various estuaries and are capable of ascending well upstream into freshwater. S. marina is found in shallow waters throughout the Chesapeake Bay. In Texas, S. marina is known to inhabit the following drainage units: Sabine Lake (including minor coastal drainages west to Galveston Bay), Galveston Bay (including minor coastal drainages west to mouth of Brazos River), Brazos River, Colorado River, San Antonio Bay (including minor coastal drainages west of mouth of Colorado River to mouth of Nueces River), Nueces River.S. marina has also been introduced and now inhabits parts of the Tennessee River drainage throughout Alabama and Tennessee.
The predators of S. marina include larger piscivorous fish such as the Atlantic tarpon (Megalops atlanticus). There are also less common predators that include S. marina in their diet such as the common bottlenose dolphin (Tursiops truncatus) and juvenile lemon sharks (Negaprion brevirostris). Since they are surface swimmers, S. marina are also preyed upon by some birds. The competitors of S. marina include similar sized piscivorous fish species such as bonefish. Although the maximum salinity of Strongylura marina is 36.9 ppt, they are able to adapt to a wide range of salinities, regularly venturing into fresh water.
Spawning typically occurs in late spring and summer. In Texas, near ripe females have been reported in February. Females lay eggs that have many long filamentous tendrils which attach to floating vegetation or other submerged objects and organisms. S. marina reaches reproductive maturity two years after being born. Spawning activity occurs in shallow inshore habitats with submerged algal masses.
S. marina is not currently considered to be a threatened species. It is not of high commercial importance, but there is a fishery for it and it is sometimes taken as bycatch. Sport fishermen take it by angling and seining, and then use it as bait.
Other common names for the fish include agujon, billfish, bluebone, garfish, green gar, harvest pike, northern needlefish, saltwater gar, sea pike, and silver gar.
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- Strongylura marina Smithsonian Marine station at Fort Pierce