Blacktip Shark 2

Blacktip Shark 2 by Inked Animal

Blacktip Shark | Carcharhinus limbatus



Blacktip Shark info via Wikipedia:

Not to be confused with the blacktip reef shark, Carcharhinus melanopterus.
Blacktip shark
Carcharhinus limbatus (2).jpg
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Selachimorpha
Order: Carcharhiniformes
Family: Carcharhinidae
Genus: Carcharhinus
Species: C. limbatus
Binomial name
Carcharhinus limbatus
(J. P. Müller & Henle, 1839)
Carcharhinus limbatus distmap.png
Range of the blacktip shark
Synonyms

Carcharias abbreviatus Klunzinger, 1871
Carcharias aethalorus Jordan & Gilbert, 1882
Carcharias ehrenbergi Klunzinger, 1871
Carcharias maculipinna Günther, 1868
Carcharias microps Lowe, 1841
Carcharias muelleri Steindachner, 1867
Carcharias phorcys Jordan & Evermann, 1903
Carcharias pleurotaenia Bleeker, 1852
Carcharhinus natator Meek & Hildebrand, 1923

The blacktip shark (Carcharhinus limbatus) is a species of requiem shark, and part of the family Carcharhinidae. It is common to coastal tropical and subtropical waters around the world, including brackish habitats. Genetic analyses have revealed substantial variation within this species, with populations from the western Atlantic Ocean isolated and distinct from those in the rest of its range. The blacktip shark has a stout, fusiform body with a pointed snout, long gill slits, and no ridge between the dorsal fins. Most individuals have black tips or edges on the pectoral, dorsal, pelvic, and caudal fins. It usually attains a length of 1.5 m (4.9 ft).

Swift, energetic piscivores, blacktip sharks are known to make spinning leaps out of the water while attacking schools of small fish. Their demeanor has been described as "timid" compared to other large requiem sharks. Both juveniles and adults form groups of varying size. Like other members of its family, the blacktip shark is viviparous; females bear one to 10 pups every other year. Young blacktip sharks spend the first months of their lives in shallow nurseries, and grown females return to the nurseries where they were born to give birth themselves. In the absence of males, females are also capable of asexual reproduction.

Normally wary of humans, blacktip sharks can become aggressive in the presence of food and have been responsible for a number of attacks on people. This species is of importance to both commercial and recreational fisheries across many parts of its range, with its meat, skin, fins, and liver oil used. It has been assessed as Near Threatened by the IUCN, on the basis of its low reproductive rate and high value to fishers.

Taxonomy

The blacktip shark was first described by French zoologist Achille Valenciennes as Carcharias (Prionodon) limbatus in Johannes Müller and Friedrich Henle's 1839 Systematische Beschreibung der Plagiostomen. The type specimens were two individuals caught off Martinique, both of which have since been lost. Later authors moved this species to the genus Carcharhinus.[1][2] The specific epithet limbatus is Latin for "bordered", referring to the black edges of this shark's fins.[3] Other common names used for the blacktip shark include blackfin shark, blacktip whaler, common or small blacktip shark, grey shark, and spotfin ground shark.[4]

Phylogeny and evolution

The closest relatives of the blacktip shark were originally thought to be the graceful shark (C. amblyrhynchoides) and the spinner shark (C. brevipinna), due to similarities in morphology and behavior. However, this interpretation has not been borne out by studies of mitochondrial and ribosomal DNA, which instead suggest affinity with the blacknose shark (C. acronotus). More work is required to fully resolve the relationship between the blacktip shark and other Carcharhinus species.[5]

Analysis of mitochondrial DNA has also revealed two distinct lineages within this species, one occupying the western Atlantic and the other occupying the eastern Atlantic, Indian, and Pacific Oceans. This suggests that Indo-Pacific blacktip sharks are descended from those in the eastern Atlantic, while the western Atlantic sharks became isolated by the widening Atlantic Ocean on one side and the formation of the Isthmus of Panama on the other. Blacktip sharks from these two regions differ in morphology, coloration, and life history characteristics, and the eastern Atlantic lineage may merit species status.[6] Fossil teeth belonging to this species have been found in Early Miocene (23–16 Ma) deposits in Delaware and Florida.[7][8]

Description

The blacktip shark has a robust, streamlined body with a long, pointed snout and relatively small eyes. The five pairs of gill slits are longer than those of similar requiem shark species.[1] The jaws contain 15 tooth rows on either side, with two symphysial teeth (at the jaw midline) in the upper jaw and one symphysial tooth in the lower jaw. The teeth are broad-based with a high, narrow cusp and serrated edges.[2] The first dorsal fin is tall and falcate (sickle-shaped) with a short free rear tip; no ridge runs between the first and second dorsal fins. The large pectoral fins are falcate and pointed.[1]

The coloration is gray to brown above and white below, with a conspicuous white stripe running along the sides. The pectoral fins, second dorsal fin, and the lower lobe of the caudal fin usually have black tips. The pelvic fins and rarely the anal fin may also be black-tipped. The first dorsal fin and the upper lobe of the caudal fin typically have black edges.[1] Some larger individuals have unmarked or nearly unmarked fins.[3] Blacktip sharks can temporarily lose almost all their colors during blooms, or "whitings", of coccolithophores.[9] This species attains a maximum known length of 2.8 m (9.2 ft), though 1.5 m (4.9 ft) is more typical, and a maximum known weight of 123 kg (271 lb).[4]

Distribution and habitat

A blacktip shark swimming in murky water off Oahu, Hawaii

The blacktip shark has a worldwide distribution in tropical and subtropical waters. In the Atlantic, it is found from Massachusetts to Brazil, including the Gulf of Mexico and the Caribbean Sea, and from the Mediterranean Sea, Madeira, and the Canary Islands to the Democratic Republic of the Congo. It occurs all around the periphery of the Indian Ocean, from South Africa and Madagascar to the Arabian Peninsula and the Indian subcontinent, to Southeast Asia. In the western Pacific, it is found from southern China to northern Australia, including the Philippines and Indonesia. In the eastern Pacific, it occurs from Baja California to Peru. It has also been reported at a number of Pacific islands, including New Caledonia, Tahiti, the Marquesas, Hawaii, Revillagigedo, and the Galápagos.[1]

Most blacktip sharks are found in water less than 30 m (98 ft) deep over continental and insular shelves, though they may dive to 64 m (210 ft).[4] Favored habitats are muddy bays, island lagoons, and the drop-offs near coral reefs; they are also tolerant of low salinity and enter estuaries and mangrove swamps. Although an individual may be found some distance offshore, blacktip sharks do not inhabit oceanic waters.[1] Seasonal migration has been documented for the population off the east coast of the United States, moving north to North Carolina in the summer and south to Florida in the winter.[10]

Biology and ecology

The blacktip shark is an extremely fast, energetic predator that is usually found in groups of varying size.[3] Segregation by sex and age does not occur; adult males and nonpregnant females are found apart from pregnant females, and both are separated from juveniles.[1] In Terra Ceia Bay, Florida, a nursery area for this species, juvenile blacktips form aggregations during the day and disperse at night. They aggregate most strongly in the early summer when the sharks are youngest, suggesting that they are seeking refuge from predators (mostly larger sharks) in numbers.[11] Predator avoidance may also be the reason why juvenile blacktips do not congregate in the areas of highest prey density in the bay.[12] Adults have no known predators.[2] Known parasites of the blacktip shark include the copepods Pandarus sinuatus and P. smithii, and the monogeneans Dermophthirius penneri and Dionchus spp., which attach the shark's skin.[2][13][14] This species is also parasitized by nematodes in the family Philometridae, which infest the ovaries.[15]

Behaviour

Blacktip sharks are social and usually found in groups.

Like the spinner shark, the blacktip shark is known to leap out of the water and spin three or four times about its axis before landing. Some of these jumps are the end product of feeding runs, in which the shark corkscrews vertically through schools of small fish and its momentum launches it into the air.[3] Observations in the Bahamas suggest that blacktip sharks may also jump out of the water to dislodge attached sharksuckers (Echeneis naucrates), which irritate the shark's skin and compromise its hydrodynamic shape.[16] The speed attained by the shark during these jumps has been estimated to average 6.3 m/s (21 ft/s).[17]

Blacktip sharks have a timid disposition and consistently lose out to Galapagos sharks (C. galapagensis) and silvertip sharks (C. albimarginatus) of equal size when competing for food.[1] If threatened or challenged, they may perform an agonistic display: the shark swims towards the threat and then turns away, while rolling from side to side, lowering its pectoral fins, tilting its head and tail upwards, and making sideways biting motions. The entire sequence lasts around 25 seconds. This behavior is similar to the actions of a shark attempting to move a sharksucker; one of these behaviors possibly is derived from the other.[18]

Feeding

Fish make up some 90% of the blacktip shark's diet.[19] A wide variety of fish have been recorded as prey for this species: sardines, herring, anchovies, ladyfish, sea catfish, cornetfish, flatfish, threadfins, mullet, mackerel, jacks, groupers, snook, porgies, mojarras, emperors, grunts, butterfish, tilapia, triggerfish, boxfish, and porcupinefish. They also feed on rays and skates, as well as smaller sharks such as smoothhounds and sharpnose sharks. Crustaceans and cephalopods are occasionally taken.[1] In the Gulf of Mexico, the most important prey of the blacktip shark is the Gulf menhaden (Brevoortia patronus), followed by the Atlantic croaker (Micropogonias undulatus).[19] Off South Africa, jacks and herring are the most important prey.[20] Hunting peaks at dawn and dusk.[19] The excitability and sociability of blacktip sharks makes them prone to feeding frenzies when large quantities of food are suddenly available, such as when fishing vessels dump their refuse overboard.[1]

Life history

As with other requiem sharks, the blacktip shark exhibits vivipary. Females typically give birth to four to seven (range one to 10) pups every other year, making use of shallow coastal nurseries that offer plentiful food and fewer predators.[1] Known nurseries include Pine Island Sound, Terra Ceia Bay, and Yankeetown along the Gulf Coast of Florida, Bulls Bay on the coast of South Carolina, and Pontal do Paraná on the coast of Brazil.[21][22] Although adult blacktip sharks are highly mobile and disperse over long distances, they are philopatric and return to their original nursery areas to give birth. This results in a series of genetically distinct breeding stocks that overlap in geographic range.[21][23]

Mating occurs from spring to early summer, and the young are born around the same time the following year after a gestation period of 10–12 months.[1] Females have one functional ovary and two functional uteri; each uterus is separated into compartments with a single embryo inside each.[24] The embryos are initially sustained by a yolk sac; in the 10th or 11th week of gestation, when the embryo measures 18–19 cm long (7.1–7.5 in), the supply of yolk is exhausted and the yolk sac develops into a placental connection that sustains the embryo until birth.[10] The length at birth is 55–60 cm (22–24 in) off the eastern United States and 61–65 cm (24–26 in) off North Africa.[10][24] The mortality rate in the first 15 months of life is 61–91%, with major threats being predation and starvation.[25] The young remain in the nurseries until their first fall, when they migrate to their wintering grounds.[10]

The growth rate of this species slows with age: 25–30 cm (9.8–11.8 in) in the first six months, then 20 cm (7.9 in) a year until the second year, then 10 cm (3.9 in) a year until maturation, then 5 cm (2.0 in) a year for adults.[26][27] The size at maturity varies geographically: males and females mature at 1.4–1.5 m (4.6–4.9 ft) and 1.6 m (5.2 ft), respectively, in the northeastern Atlantic,[10] 1.3–1.4 m (4.3–4.6 ft) and 1.5–1.6 m (4.9–5.2 ft), respectively, in the Gulf of Mexico,[26][28] 1.5 and 1.6 m (4.9 and 5.2 ft) respectively off South Africa,[29] and 1.7 and 1.8 m (5.6 and 5.9 ft), respectively, off North Africa.[24] The age at maturation is 4–5 years for males and 7–8 years for females.[26][28] The lifespan is at least 12 years.[1]

In 2007, a 9-year-old female blacktip shark at the Virginia Aquarium and Marine Science Center was found to be pregnant with a single near-term female pup, despite having never mated with a male. Genetic analysis confirmed that her offspring was the product of automictic parthenogenesis, a form of asexual reproduction in which an ovum merges with a polar body to form a zygote without fertilization. Along with an earlier case of parthenogenesis in the bonnethead (Sphyrna tiburo), this event suggests that asexual reproduction may be more widespread in sharks than previously thought.[30]

Human interactions

The blacktip shark usually poses little danger to divers.

Blacktip sharks showing curiosity towards divers has been reported, but they remain at a safe distance. Under most circumstances, these timid sharks are not regarded as highly dangerous to humans. However, they may become aggressive in the presence of food, and their size and speed invite respect.[1] As of 2008, the International Shark Attack File lists 28 unprovoked attacks (one fatal) and 13 provoked attacks by this species.[31] Blacktip sharks are responsible annually for 16% of the shark attacks around Florida. Most attacks by this species result in only minor wounds.[2]

As one of the most common large sharks in coastal waters, the blacktip shark is caught in large numbers by commercial fisheries throughout the world, using longlines, fixed-bottom nets, bottom trawls, and hook-and-line. The meat is of high quality and marketed fresh, frozen, or dried and salted. In addition, the fins are used for shark fin soup, the skin for leather, the liver oil for vitamins, and the carcasses for fishmeal.[1] Blacktip sharks are one of the most important species to the northwestern Atlantic shark fishery, second only to the sandbar shark (C. plumbeus). The flesh is considered superior to that of the sandbar shark, resulting in the sandbar and other requiem shark species being sold under the name "blacktip shark" in the United States. The blacktip shark is also very significant to Indian and Mexican fisheries, and is caught in varying numbers by fisheries in the Mediterranean and South China Seas, and off northern Australia.[27]

The blacktip shark is popular with recreational anglers in Florida, the Caribbean, and South Africa. It is listed as a game fish by the International Game Fish Association. Once hooked, this species is a strong, steady fighter that sometimes jumps out of the water.[2] Since 1995, the number of blacktip sharks taken by recreational anglers in the United States has approached or surpassed the number taken by commercial fishing.[27] The International Union for Conservation of Nature has assessed the blacktip shark as Near Threatened, as its low reproductive rate renders it vulnerable to overfishing.[32] The United States and Australia are the only two countries that manage fisheries catching blacktip sharks. In both cases, regulation occurs under umbrella management schemes for multiple shark species, such as that for the large coastal sharks category of the US National Marine Fisheries Service Atlantic shark Fisheries Management Plan. No conservation plans specifically for this species have been implemented.[27]

References

  1. ^ a b c d e f g h i j k l m n o Compagno, L.J.V. (1984). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Rome: Food and Agricultural Organization. pp. 481–483. ISBN 92-5-101384-5. 
  2. ^ a b c d e f Curtis, T. Biological Profiles: Blacktip Shark. Florida Museum of Natural History Ichthyology Department. Retrieved on April 27, 2009.
  3. ^ a b c d Ebert, D.A. (2003). Sharks, Rays, and Chimaeras of California. London: University of California Press. pp. 156–157. ISBN 0-520-23484-7. 
  4. ^ a b c Froese, Rainer and Pauly, Daniel, eds. (2009). "Carcharhinus limbatus" in FishBase. April 2009 version.
  5. ^ Dosay-Akbulut, M. (2008). "The phylogenetic relationship within the genus Carcharhinus". Comptes Rendus Biologies. 331 (7): 500–509. doi:10.1016/j.crvi.2008.04.001. PMID 18558373. 
  6. ^ Keeney, D.B. & Heist, E.J. (October 2006). "Worldwide phylogeography of the blacktip shark (Carcharhinus limbatus) inferred from mitochondrial DNA reveals isolation of western Atlantic populations coupled with recent Pacific dispersal". Molecular Ecology. 15 (12): 3669–3679. doi:10.1111/j.1365-294X.2006.03036.x. PMID 17032265. 
  7. ^ Benson. R.N., ed. (1998). Geology and Paleontology of the Lower Miocene Pollack Farm Fossil Site, Delaware: Delaware Geological Survey Special Publication No. 21. Delaware Natural History Survey. pp. 133–139. 
  8. ^ Brown, R.C. (2008). Florida's Fossils: Guide to Location, Identification, and Enjoyment (third ed.). Pineapple Press Inc. p. 100. ISBN 1-56164-409-9. 
  9. ^ Martin, R.A. Albinism in Sharks. ReefQuest Centre for Shark Research. Retrieved on April 28, 2009.
  10. ^ a b c d e Castro, J.I. (November 1996). "Biology of the blacktip shark, Carcharhinus limbatus, off the southeastern United States". Bulletin of Marine Science. 59 (3): 508–522. 
  11. ^ Heupel, M.R. & Simpfendorfer, C.A. (2005). "Quantitative analysis of aggregation behavior in juvenile blacktip sharks". Marine Biology. 147 (5): 1239–1249. doi:10.1007/s00227-005-0004-7. 
  12. ^ Heupel, M.R. & Hueter, R.E. (2002). "The importance of prey density in relation to the movement patterns of juvenile sharks within a coastal nursery area". Marine and Freshwater Research. 53 (2): 543–550. doi:10.1071/MF01132. 
  13. ^ Bullard, S.A.; Frasca, A. (Jr.) & Benz, G.W. (June 2000). "Skin Lesions Caused by Dermophthirius penneri (Monogenea: Microbothriidae) on Wild-Caught Blacktip Sharks (Carcharhinus limbatus)". Journal of Parasitology. 86 (3): 618–622. doi:10.1645/0022-3395(2000)086[0618:SLCBDP]2.0.CO;2. PMID 10864264. CS1 maint: Date and year (link)
  14. ^ Bullard, S.A.; Benz, G.W. & Braswell, J.S. (2000). "Dionchus postoncomiracidia (Monogenea: Dionchidae) from the skin of blacktip sharks, Carcharhinus limbatus (Carcharhinidae)". Journal of Parasitology. 86 (2): 245–250. doi:10.1645/0022-3395(2000)086[0245:DPMDFT]2.0.CO;2. JSTOR 3284763. PMID 10780540. 
  15. ^ Rosa-Molinar, E. & Williams, C.S. (1983). "Larval nematodes (Philometridae) in granulomas in ovaries of blacktip sharks, Carcharhinus limbatus (Valenciennes)". Journal of Wildlife Diseases. 19 (3): 275–277. doi:10.7589/0090-3558-19.3.275. PMID 6644926. 
  16. ^ Riner, E.K. & Brijnnschweiler, J.M. (2003). "Do sharksuckers, Echeneis naucrates, induce jump behaviour in blacktip sharks, Carcharhinus limbatus?". Marine and Freshwater Behaviour and Physiology. 36 (2): 111–113. doi:10.1080/1023624031000119584. 
  17. ^ Brunnschweiler, J.M. (2005). "Water-escape velocities in jumping blacktip sharks". Journal of the Royal Society Interface. 2 (4): 389–391. doi:10.1098/rsif.2005.0047. PMC 1578268Freely accessible. PMID 16849197. 
  18. ^ Ritter, E.K. & Godknecht, A.J. (February 1, 2000). Ross, S. T., ed. "Agonistic Displays in the Blacktip Shark (Carcharhinus limbatus)". Copeia. 2000 (1): 282–284. doi:10.1643/0045-8511(2000)2000[0282:ADITBS]2.0.CO;2. JSTOR 1448264. CS1 maint: Date and year (link)
  19. ^ a b c Barry, K.P. (2002). Feeding habits of blacktip sharks, Carcharhinus limbatus, and Atlantic sharpnose sharks, Rhizoprionodon terraenovae, in Louisiana coastal waters. MS thesis, Louisiana State University, Baton Rouge.
  20. ^ Dudley, S.F.J. & Cliff, G. (1993). "Sharks caught in the protective gill nets off Natal, South Africa. 7. The blacktip shark Carcharhinus limbatus (Valenciennes)". African Journal of Marine Science. 13: 237–254. doi:10.2989/025776193784287356. 
  21. ^ a b Keeney, D.B.; Heupel, M.; Hueter, R.E. & Heist, E.J. (2003). "Genetic heterogeneity among blacktip shark, Carcharhinus limbatus, continental nurseries along the U.S. Atlantic and Gulf of Mexico". Marine Biology. 143 (6): 1039–1046. doi:10.1007/s00227-003-1166-9. 
  22. ^ Bornatowski, H. (2008). "A parturition and nursery area for Carcharhinus limbatus (Elasmobranchii, Carcharhinidae) off the coast of Paraná, Brazil". Brazilian Journal of Oceanography. 56 (4): 317–319. doi:10.1590/s1679-87592008000400008. 
  23. ^ Keeney, D.B.; Heupel, M.R.; Hueter, R.E. & Heist, E.J. (2005). "Microsatellite and mitochondrial DNA analyses of the genetic structure of blacktip shark (Carcharhinus limbatus) nurseries in the northwestern Atlantic, Gulf of Mexico, and Caribbean Sea". Molecular Ecology. 14 (7): 1911–1923. doi:10.1111/j.1365-294X.2005.02549.x. PMID 15910315. 
  24. ^ a b c Capapé, C.H.; Seck, A.A.; Diatta, Y.; Reynaud, C.H.; Hemida, F. & Zaouali, J. (2004). "Reproductive biology of the blacktip shark, Carcharhinus limbatus (Chondrichthyes: Carcharhinidae) off West and North African Coasts" (PDF). Cybium. 28 (4): 275–284. 
  25. ^ Heupel, M.R. & Simpfendorfer, C.A. (2002). "Estimation of mortality of juvenile blacktip sharks, Carcharhinus limbatus, within a nursery area using telemetry data". Canadian Journal of Fisheries and Aquatic Sciences. 59 (4): 624–632. doi:10.1139/f02-036. 
  26. ^ a b c Branstetter, S. (December 9, 1987). "Age and Growth Estimates for Blacktip, Carcharhinus limbatus, and Spinner, C. brevipinna, Sharks from the Northwestern Gulf of Mexico". Copeia. American Society of Ichthyologists and Herpetologists. 1987 (4): 964–974. doi:10.2307/1445560. JSTOR 1445560. 
  27. ^ a b c d Fowler, S.L.; Cavanagh, R.D.; Camhi, M.; Burgess, G.H.; Cailliet, G.M.; Fordham, S.V.; Simpfendorfer, C.A. & Musick, J.A. (2005). Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes. International Union for Conservation of Nature and Natural Resources. pp. 106–109, 293–295. ISBN 2-8317-0700-5. 
  28. ^ a b Killam, K.A. & Parsons, G.R. (May 1989). "Age and Growth of the Blacktip Shark, Carcharhinus limbatus, near Tampa Bay" (PDF). Florida Fishery Bulletin. 87: 845–857. 
  29. ^ Wintner, S.P. & Cliff, G. (1996). "Age and growth determination of the blacktip shark, Carcharhinus limbatus, from the east coast of South Africa" (PDF). Fishery Bulletin. 94 (1): 135–144. 
  30. ^ Chapman, D.D.; Firchau, B. & Shivji, M.S. (2008). "Parthenogenesis in a large-bodied requiem shark, the blacktip Carcharhinus limbatus". Journal of Fish Biology. 73 (6): 1473–1477. doi:10.1111/j.1095-8649.2008.02018.x. 
  31. ^ ISAF Statistics on Attacking Species of Shark. International Shark Attack File, Florida Museum of Natural History, University of Florida. Retrieved on April 22, 2009.
  32. ^ Musick, J.A.; Fowler, S. (2000). "Carcharhinus limbatus". IUCN Red List of Threatened Species. Version 2007. International Union for Conservation of Nature. Retrieved April 27, 2009. 
source: http://en.wikipedia.org/wiki/Blacktip_shark

Blacktip Shark 1

Blacktip Shark by Inked Animal

Blacktip Shark | Carcharhinus limbatus

 


Blacktip Shark info via Wikipedia:

Not to be confused with the blacktip reef shark, Carcharhinus melanopterus.
Blacktip shark
Carcharhinus limbatus (2).jpg
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Superorder: Selachimorpha
Order: Carcharhiniformes
Family: Carcharhinidae
Genus: Carcharhinus
Species: C. limbatus
Binomial name
Carcharhinus limbatus
(J. P. Müller & Henle, 1839)
Carcharhinus limbatus distmap.png
Range of the blacktip shark
Synonyms

Carcharias abbreviatus Klunzinger, 1871
Carcharias aethalorus Jordan & Gilbert, 1882
Carcharias ehrenbergi Klunzinger, 1871
Carcharias maculipinna Günther, 1868
Carcharias microps Lowe, 1841
Carcharias muelleri Steindachner, 1867
Carcharias phorcys Jordan & Evermann, 1903
Carcharias pleurotaenia Bleeker, 1852
Carcharhinus natator Meek & Hildebrand, 1923

The blacktip shark (Carcharhinus limbatus) is a species of requiem shark, and part of the family Carcharhinidae. It is common to coastal tropical and subtropical waters around the world, including brackish habitats. Genetic analyses have revealed substantial variation within this species, with populations from the western Atlantic Ocean isolated and distinct from those in the rest of its range. The blacktip shark has a stout, fusiform body with a pointed snout, long gill slits, and no ridge between the dorsal fins. Most individuals have black tips or edges on the pectoral, dorsal, pelvic, and caudal fins. It usually attains a length of 1.5 m (4.9 ft).

Swift, energetic piscivores, blacktip sharks are known to make spinning leaps out of the water while attacking schools of small fish. Their demeanor has been described as "timid" compared to other large requiem sharks. Both juveniles and adults form groups of varying size. Like other members of its family, the blacktip shark is viviparous; females bear one to 10 pups every other year. Young blacktip sharks spend the first months of their lives in shallow nurseries, and grown females return to the nurseries where they were born to give birth themselves. In the absence of males, females are also capable of asexual reproduction.

Normally wary of humans, blacktip sharks can become aggressive in the presence of food and have been responsible for a number of attacks on people. This species is of importance to both commercial and recreational fisheries across many parts of its range, with its meat, skin, fins, and liver oil used. It has been assessed as Near Threatened by the IUCN, on the basis of its low reproductive rate and high value to fishers.

Taxonomy

The blacktip shark was first described by French zoologist Achille Valenciennes as Carcharias (Prionodon) limbatus in Johannes Müller and Friedrich Henle's 1839 Systematische Beschreibung der Plagiostomen. The type specimens were two individuals caught off Martinique, both of which have since been lost. Later authors moved this species to the genus Carcharhinus.[1][2] The specific epithet limbatus is Latin for "bordered", referring to the black edges of this shark's fins.[3] Other common names used for the blacktip shark include blackfin shark, blacktip whaler, common or small blacktip shark, grey shark, and spotfin ground shark.[4]

Phylogeny and evolution

The closest relatives of the blacktip shark were originally thought to be the graceful shark (C. amblyrhynchoides) and the spinner shark (C. brevipinna), due to similarities in morphology and behavior. However, this interpretation has not been borne out by studies of mitochondrial and ribosomal DNA, which instead suggest affinity with the blacknose shark (C. acronotus). More work is required to fully resolve the relationship between the blacktip shark and other Carcharhinus species.[5]

Analysis of mitochondrial DNA has also revealed two distinct lineages within this species, one occupying the western Atlantic and the other occupying the eastern Atlantic, Indian, and Pacific Oceans. This suggests that Indo-Pacific blacktip sharks are descended from those in the eastern Atlantic, while the western Atlantic sharks became isolated by the widening Atlantic Ocean on one side and the formation of the Isthmus of Panama on the other. Blacktip sharks from these two regions differ in morphology, coloration, and life history characteristics, and the eastern Atlantic lineage may merit species status.[6] Fossil teeth belonging to this species have been found in Early Miocene (23–16 Ma) deposits in Delaware and Florida.[7][8]

Description

The blacktip shark has a robust, streamlined body with a long, pointed snout and relatively small eyes. The five pairs of gill slits are longer than those of similar requiem shark species.[1] The jaws contain 15 tooth rows on either side, with two symphysial teeth (at the jaw midline) in the upper jaw and one symphysial tooth in the lower jaw. The teeth are broad-based with a high, narrow cusp and serrated edges.[2] The first dorsal fin is tall and falcate (sickle-shaped) with a short free rear tip; no ridge runs between the first and second dorsal fins. The large pectoral fins are falcate and pointed.[1]

The coloration is gray to brown above and white below, with a conspicuous white stripe running along the sides. The pectoral fins, second dorsal fin, and the lower lobe of the caudal fin usually have black tips. The pelvic fins and rarely the anal fin may also be black-tipped. The first dorsal fin and the upper lobe of the caudal fin typically have black edges.[1] Some larger individuals have unmarked or nearly unmarked fins.[3] Blacktip sharks can temporarily lose almost all their colors during blooms, or "whitings", of coccolithophores.[9] This species attains a maximum known length of 2.8 m (9.2 ft), though 1.5 m (4.9 ft) is more typical, and a maximum known weight of 123 kg (271 lb).[4]

Distribution and habitat

A blacktip shark swimming in murky water off Oahu, Hawaii

The blacktip shark has a worldwide distribution in tropical and subtropical waters. In the Atlantic, it is found from Massachusetts to Brazil, including the Gulf of Mexico and the Caribbean Sea, and from the Mediterranean Sea, Madeira, and the Canary Islands to the Democratic Republic of the Congo. It occurs all around the periphery of the Indian Ocean, from South Africa and Madagascar to the Arabian Peninsula and the Indian subcontinent, to Southeast Asia. In the western Pacific, it is found from southern China to northern Australia, including the Philippines and Indonesia. In the eastern Pacific, it occurs from Baja California to Peru. It has also been reported at a number of Pacific islands, including New Caledonia, Tahiti, the Marquesas, Hawaii, Revillagigedo, and the Galápagos.[1]

Most blacktip sharks are found in water less than 30 m (98 ft) deep over continental and insular shelves, though they may dive to 64 m (210 ft).[4] Favored habitats are muddy bays, island lagoons, and the drop-offs near coral reefs; they are also tolerant of low salinity and enter estuaries and mangrove swamps. Although an individual may be found some distance offshore, blacktip sharks do not inhabit oceanic waters.[1] Seasonal migration has been documented for the population off the east coast of the United States, moving north to North Carolina in the summer and south to Florida in the winter.[10]

Biology and ecology

The blacktip shark is an extremely fast, energetic predator that is usually found in groups of varying size.[3] Segregation by sex and age does not occur; adult males and nonpregnant females are found apart from pregnant females, and both are separated from juveniles.[1] In Terra Ceia Bay, Florida, a nursery area for this species, juvenile blacktips form aggregations during the day and disperse at night. They aggregate most strongly in the early summer when the sharks are youngest, suggesting that they are seeking refuge from predators (mostly larger sharks) in numbers.[11] Predator avoidance may also be the reason why juvenile blacktips do not congregate in the areas of highest prey density in the bay.[12] Adults have no known predators.[2] Known parasites of the blacktip shark include the copepods Pandarus sinuatus and P. smithii, and the monogeneans Dermophthirius penneri and Dionchus spp., which attach the shark's skin.[2][13][14] This species is also parasitized by nematodes in the family Philometridae, which infest the ovaries.[15]

Behaviour

Blacktip sharks are social and usually found in groups.

Like the spinner shark, the blacktip shark is known to leap out of the water and spin three or four times about its axis before landing. Some of these jumps are the end product of feeding runs, in which the shark corkscrews vertically through schools of small fish and its momentum launches it into the air.[3] Observations in the Bahamas suggest that blacktip sharks may also jump out of the water to dislodge attached sharksuckers (Echeneis naucrates), which irritate the shark's skin and compromise its hydrodynamic shape.[16] The speed attained by the shark during these jumps has been estimated to average 6.3 m/s (21 ft/s).[17]

Blacktip sharks have a timid disposition and consistently lose out to Galapagos sharks (C. galapagensis) and silvertip sharks (C. albimarginatus) of equal size when competing for food.[1] If threatened or challenged, they may perform an agonistic display: the shark swims towards the threat and then turns away, while rolling from side to side, lowering its pectoral fins, tilting its head and tail upwards, and making sideways biting motions. The entire sequence lasts around 25 seconds. This behavior is similar to the actions of a shark attempting to move a sharksucker; one of these behaviors possibly is derived from the other.[18]

Feeding

Fish make up some 90% of the blacktip shark's diet.[19] A wide variety of fish have been recorded as prey for this species: sardines, herring, anchovies, ladyfish, sea catfish, cornetfish, flatfish, threadfins, mullet, mackerel, jacks, groupers, snook, porgies, mojarras, emperors, grunts, butterfish, tilapia, triggerfish, boxfish, and porcupinefish. They also feed on rays and skates, as well as smaller sharks such as smoothhounds and sharpnose sharks. Crustaceans and cephalopods are occasionally taken.[1] In the Gulf of Mexico, the most important prey of the blacktip shark is the Gulf menhaden (Brevoortia patronus), followed by the Atlantic croaker (Micropogonias undulatus).[19] Off South Africa, jacks and herring are the most important prey.[20] Hunting peaks at dawn and dusk.[19] The excitability and sociability of blacktip sharks makes them prone to feeding frenzies when large quantities of food are suddenly available, such as when fishing vessels dump their refuse overboard.[1]

Life history

As with other requiem sharks, the blacktip shark exhibits vivipary. Females typically give birth to four to seven (range one to 10) pups every other year, making use of shallow coastal nurseries that offer plentiful food and fewer predators.[1] Known nurseries include Pine Island Sound, Terra Ceia Bay, and Yankeetown along the Gulf Coast of Florida, Bulls Bay on the coast of South Carolina, and Pontal do Paraná on the coast of Brazil.[21][22] Although adult blacktip sharks are highly mobile and disperse over long distances, they are philopatric and return to their original nursery areas to give birth. This results in a series of genetically distinct breeding stocks that overlap in geographic range.[21][23]

Mating occurs from spring to early summer, and the young are born around the same time the following year after a gestation period of 10–12 months.[1] Females have one functional ovary and two functional uteri; each uterus is separated into compartments with a single embryo inside each.[24] The embryos are initially sustained by a yolk sac; in the 10th or 11th week of gestation, when the embryo measures 18–19 cm long (7.1–7.5 in), the supply of yolk is exhausted and the yolk sac develops into a placental connection that sustains the embryo until birth.[10] The length at birth is 55–60 cm (22–24 in) off the eastern United States and 61–65 cm (24–26 in) off North Africa.[10][24] The mortality rate in the first 15 months of life is 61–91%, with major threats being predation and starvation.[25] The young remain in the nurseries until their first fall, when they migrate to their wintering grounds.[10]

The growth rate of this species slows with age: 25–30 cm (9.8–11.8 in) in the first six months, then 20 cm (7.9 in) a year until the second year, then 10 cm (3.9 in) a year until maturation, then 5 cm (2.0 in) a year for adults.[26][27] The size at maturity varies geographically: males and females mature at 1.4–1.5 m (4.6–4.9 ft) and 1.6 m (5.2 ft), respectively, in the northeastern Atlantic,[10] 1.3–1.4 m (4.3–4.6 ft) and 1.5–1.6 m (4.9–5.2 ft), respectively, in the Gulf of Mexico,[26][28] 1.5 and 1.6 m (4.9 and 5.2 ft) respectively off South Africa,[29] and 1.7 and 1.8 m (5.6 and 5.9 ft), respectively, off North Africa.[24] The age at maturation is 4–5 years for males and 7–8 years for females.[26][28] The lifespan is at least 12 years.[1]

In 2007, a 9-year-old female blacktip shark at the Virginia Aquarium and Marine Science Center was found to be pregnant with a single near-term female pup, despite having never mated with a male. Genetic analysis confirmed that her offspring was the product of automictic parthenogenesis, a form of asexual reproduction in which an ovum merges with a polar body to form a zygote without fertilization. Along with an earlier case of parthenogenesis in the bonnethead (Sphyrna tiburo), this event suggests that asexual reproduction may be more widespread in sharks than previously thought.[30]

Human interactions

The blacktip shark usually poses little danger to divers.

Blacktip sharks showing curiosity towards divers has been reported, but they remain at a safe distance. Under most circumstances, these timid sharks are not regarded as highly dangerous to humans. However, they may become aggressive in the presence of food, and their size and speed invite respect.[1] As of 2008, the International Shark Attack File lists 28 unprovoked attacks (one fatal) and 13 provoked attacks by this species.[31] Blacktip sharks are responsible annually for 16% of the shark attacks around Florida. Most attacks by this species result in only minor wounds.[2]

As one of the most common large sharks in coastal waters, the blacktip shark is caught in large numbers by commercial fisheries throughout the world, using longlines, fixed-bottom nets, bottom trawls, and hook-and-line. The meat is of high quality and marketed fresh, frozen, or dried and salted. In addition, the fins are used for shark fin soup, the skin for leather, the liver oil for vitamins, and the carcasses for fishmeal.[1] Blacktip sharks are one of the most important species to the northwestern Atlantic shark fishery, second only to the sandbar shark (C. plumbeus). The flesh is considered superior to that of the sandbar shark, resulting in the sandbar and other requiem shark species being sold under the name "blacktip shark" in the United States. The blacktip shark is also very significant to Indian and Mexican fisheries, and is caught in varying numbers by fisheries in the Mediterranean and South China Seas, and off northern Australia.[27]

The blacktip shark is popular with recreational anglers in Florida, the Caribbean, and South Africa. It is listed as a game fish by the International Game Fish Association. Once hooked, this species is a strong, steady fighter that sometimes jumps out of the water.[2] Since 1995, the number of blacktip sharks taken by recreational anglers in the United States has approached or surpassed the number taken by commercial fishing.[27] The International Union for Conservation of Nature has assessed the blacktip shark as Near Threatened, as its low reproductive rate renders it vulnerable to overfishing.[32] The United States and Australia are the only two countries that manage fisheries catching blacktip sharks. In both cases, regulation occurs under umbrella management schemes for multiple shark species, such as that for the large coastal sharks category of the US National Marine Fisheries Service Atlantic shark Fisheries Management Plan. No conservation plans specifically for this species have been implemented.[27]

References

  1. ^ a b c d e f g h i j k l m n o Compagno, L.J.V. (1984). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Rome: Food and Agricultural Organization. pp. 481–483. ISBN 92-5-101384-5. 
  2. ^ a b c d e f Curtis, T. Biological Profiles: Blacktip Shark. Florida Museum of Natural History Ichthyology Department. Retrieved on April 27, 2009.
  3. ^ a b c d Ebert, D.A. (2003). Sharks, Rays, and Chimaeras of California. London: University of California Press. pp. 156–157. ISBN 0-520-23484-7. 
  4. ^ a b c Froese, Rainer and Pauly, Daniel, eds. (2009). "Carcharhinus limbatus" in FishBase. April 2009 version.
  5. ^ Dosay-Akbulut, M. (2008). "The phylogenetic relationship within the genus Carcharhinus". Comptes Rendus Biologies. 331 (7): 500–509. doi:10.1016/j.crvi.2008.04.001. PMID 18558373. 
  6. ^ Keeney, D.B. & Heist, E.J. (October 2006). "Worldwide phylogeography of the blacktip shark (Carcharhinus limbatus) inferred from mitochondrial DNA reveals isolation of western Atlantic populations coupled with recent Pacific dispersal". Molecular Ecology. 15 (12): 3669–3679. doi:10.1111/j.1365-294X.2006.03036.x. PMID 17032265. 
  7. ^ Benson. R.N., ed. (1998). Geology and Paleontology of the Lower Miocene Pollack Farm Fossil Site, Delaware: Delaware Geological Survey Special Publication No. 21. Delaware Natural History Survey. pp. 133–139. 
  8. ^ Brown, R.C. (2008). Florida's Fossils: Guide to Location, Identification, and Enjoyment (third ed.). Pineapple Press Inc. p. 100. ISBN 1-56164-409-9. 
  9. ^ Martin, R.A. Albinism in Sharks. ReefQuest Centre for Shark Research. Retrieved on April 28, 2009.
  10. ^ a b c d e Castro, J.I. (November 1996). "Biology of the blacktip shark, Carcharhinus limbatus, off the southeastern United States". Bulletin of Marine Science. 59 (3): 508–522. 
  11. ^ Heupel, M.R. & Simpfendorfer, C.A. (2005). "Quantitative analysis of aggregation behavior in juvenile blacktip sharks". Marine Biology. 147 (5): 1239–1249. doi:10.1007/s00227-005-0004-7. 
  12. ^ Heupel, M.R. & Hueter, R.E. (2002). "The importance of prey density in relation to the movement patterns of juvenile sharks within a coastal nursery area". Marine and Freshwater Research. 53 (2): 543–550. doi:10.1071/MF01132. 
  13. ^ Bullard, S.A.; Frasca, A. (Jr.) & Benz, G.W. (June 2000). "Skin Lesions Caused by Dermophthirius penneri (Monogenea: Microbothriidae) on Wild-Caught Blacktip Sharks (Carcharhinus limbatus)". Journal of Parasitology. 86 (3): 618–622. doi:10.1645/0022-3395(2000)086[0618:SLCBDP]2.0.CO;2. PMID 10864264. CS1 maint: Date and year (link)
  14. ^ Bullard, S.A.; Benz, G.W. & Braswell, J.S. (2000). "Dionchus postoncomiracidia (Monogenea: Dionchidae) from the skin of blacktip sharks, Carcharhinus limbatus (Carcharhinidae)". Journal of Parasitology. 86 (2): 245–250. doi:10.1645/0022-3395(2000)086[0245:DPMDFT]2.0.CO;2. JSTOR 3284763. PMID 10780540. 
  15. ^ Rosa-Molinar, E. & Williams, C.S. (1983). "Larval nematodes (Philometridae) in granulomas in ovaries of blacktip sharks, Carcharhinus limbatus (Valenciennes)". Journal of Wildlife Diseases. 19 (3): 275–277. doi:10.7589/0090-3558-19.3.275. PMID 6644926. 
  16. ^ Riner, E.K. & Brijnnschweiler, J.M. (2003). "Do sharksuckers, Echeneis naucrates, induce jump behaviour in blacktip sharks, Carcharhinus limbatus?". Marine and Freshwater Behaviour and Physiology. 36 (2): 111–113. doi:10.1080/1023624031000119584. 
  17. ^ Brunnschweiler, J.M. (2005). "Water-escape velocities in jumping blacktip sharks". Journal of the Royal Society Interface. 2 (4): 389–391. doi:10.1098/rsif.2005.0047. PMC 1578268Freely accessible. PMID 16849197. 
  18. ^ Ritter, E.K. & Godknecht, A.J. (February 1, 2000). Ross, S. T., ed. "Agonistic Displays in the Blacktip Shark (Carcharhinus limbatus)". Copeia. 2000 (1): 282–284. doi:10.1643/0045-8511(2000)2000[0282:ADITBS]2.0.CO;2. JSTOR 1448264. CS1 maint: Date and year (link)
  19. ^ a b c Barry, K.P. (2002). Feeding habits of blacktip sharks, Carcharhinus limbatus, and Atlantic sharpnose sharks, Rhizoprionodon terraenovae, in Louisiana coastal waters. MS thesis, Louisiana State University, Baton Rouge.
  20. ^ Dudley, S.F.J. & Cliff, G. (1993). "Sharks caught in the protective gill nets off Natal, South Africa. 7. The blacktip shark Carcharhinus limbatus (Valenciennes)". African Journal of Marine Science. 13: 237–254. doi:10.2989/025776193784287356. 
  21. ^ a b Keeney, D.B.; Heupel, M.; Hueter, R.E. & Heist, E.J. (2003). "Genetic heterogeneity among blacktip shark, Carcharhinus limbatus, continental nurseries along the U.S. Atlantic and Gulf of Mexico". Marine Biology. 143 (6): 1039–1046. doi:10.1007/s00227-003-1166-9. 
  22. ^ Bornatowski, H. (2008). "A parturition and nursery area for Carcharhinus limbatus (Elasmobranchii, Carcharhinidae) off the coast of Paraná, Brazil". Brazilian Journal of Oceanography. 56 (4): 317–319. doi:10.1590/s1679-87592008000400008. 
  23. ^ Keeney, D.B.; Heupel, M.R.; Hueter, R.E. & Heist, E.J. (2005). "Microsatellite and mitochondrial DNA analyses of the genetic structure of blacktip shark (Carcharhinus limbatus) nurseries in the northwestern Atlantic, Gulf of Mexico, and Caribbean Sea". Molecular Ecology. 14 (7): 1911–1923. doi:10.1111/j.1365-294X.2005.02549.x. PMID 15910315. 
  24. ^ a b c Capapé, C.H.; Seck, A.A.; Diatta, Y.; Reynaud, C.H.; Hemida, F. & Zaouali, J. (2004). "Reproductive biology of the blacktip shark, Carcharhinus limbatus (Chondrichthyes: Carcharhinidae) off West and North African Coasts" (PDF). Cybium. 28 (4): 275–284. 
  25. ^ Heupel, M.R. & Simpfendorfer, C.A. (2002). "Estimation of mortality of juvenile blacktip sharks, Carcharhinus limbatus, within a nursery area using telemetry data". Canadian Journal of Fisheries and Aquatic Sciences. 59 (4): 624–632. doi:10.1139/f02-036. 
  26. ^ a b c Branstetter, S. (December 9, 1987). "Age and Growth Estimates for Blacktip, Carcharhinus limbatus, and Spinner, C. brevipinna, Sharks from the Northwestern Gulf of Mexico". Copeia. American Society of Ichthyologists and Herpetologists. 1987 (4): 964–974. doi:10.2307/1445560. JSTOR 1445560. 
  27. ^ a b c d Fowler, S.L.; Cavanagh, R.D.; Camhi, M.; Burgess, G.H.; Cailliet, G.M.; Fordham, S.V.; Simpfendorfer, C.A. & Musick, J.A. (2005). Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes. International Union for Conservation of Nature and Natural Resources. pp. 106–109, 293–295. ISBN 2-8317-0700-5. 
  28. ^ a b Killam, K.A. & Parsons, G.R. (May 1989). "Age and Growth of the Blacktip Shark, Carcharhinus limbatus, near Tampa Bay" (PDF). Florida Fishery Bulletin. 87: 845–857. 
  29. ^ Wintner, S.P. & Cliff, G. (1996). "Age and growth determination of the blacktip shark, Carcharhinus limbatus, from the east coast of South Africa" (PDF). Fishery Bulletin. 94 (1): 135–144. 
  30. ^ Chapman, D.D.; Firchau, B. & Shivji, M.S. (2008). "Parthenogenesis in a large-bodied requiem shark, the blacktip Carcharhinus limbatus". Journal of Fish Biology. 73 (6): 1473–1477. doi:10.1111/j.1095-8649.2008.02018.x. 
  31. ^ ISAF Statistics on Attacking Species of Shark. International Shark Attack File, Florida Museum of Natural History, University of Florida. Retrieved on April 22, 2009.
  32. ^ Musick, J.A.; Fowler, S. (2000). "Carcharhinus limbatus". IUCN Red List of Threatened Species. Version 2007. International Union for Conservation of Nature. Retrieved April 27, 2009. 
source: http://en.wikipedia.org/wiki/Blacktip_shark

Gafftopsail Catfish 2


Gafftopsail Catfish 2 by Inked Animal
Gafftopsail Catfish | Bagre marinus

 This Gyotaku deserves to be on a chinese restaurant’s wall.  Its very asian looking with the extremely falcate fins.  This animal was caught by either Adam or myself on a fishing trip to Matagorda Bay, one of our usual stomping grounds and sources for much of our saltwater material.  It is an interesting print, and misleading categorization, being that it doesn’t have scales.  Many catfish don’t have scales, but smooth skin which comes out in this print in an interesting way. Notice the wrinkles and paper creases.  Also, the long “swoop” from its chin back is the very long barbel that is covered in essentially taste buds.  Its what this animal uses to sense food.  If you like cats, make sure you check out Gafftop Catfish, Hardhead Catfish, and Hardhead Catfish – head.

 

 

 

 

 

 


 

Gafftopsail Catfish info via wikipedia:

Gafftopsail catfish
Bagre marinus (line art).jpg
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Siluriformes
Family: Ariidae
Genus: Bagre
Species: B. marinus
Binomial name
Bagre marinus
(Mitchill, 1815)
Synonyms

Felichthys felis (L.)[2]

The gafftopsail catfish, Bagre marinus, is found in the waters of the western central Atlantic Ocean, as well as the Gulf of Mexico and the Caribbean Sea. It has long venomous spines which can cause painful wounds. It feeds on crustaceans and other fish. The male of the species fertilizes the eggs of the female, and broods them in his mouth until they hatch. The gafftopsail feeds throughout the water column. This fish is a common catch in the Southeastern US, although it may be found as far north as New York. In fishing, they are considered strong fighters. They are taken from piers, jetties, reefs, and the surf, as well as bottom fishing or flats fishing. They are caught with lures, cut bait, and shrimp, as well as soft plastics. Some fishermen use traps for catfish, which is regulated by some states.

Distribution

It lives on the Atlantic, Caribbean and Gulf of Mexico coastlines from Cape Cod to Brazil.[1] It is also found in brackish waters, including estuaries, lagoons, brackish seas, and mangroves. It is generally common to abundant in its range.[1]

Characteristics

The gafftopsail catfish is blue-grey to dark brown with a light grey belly. Its appearance is typical for a catfish except for the deeply forked tail and the venomous, serrated spines. It also has a little hump that looks somewhat like a wave. The typical length of a mature gafftopsail catfish is about 17 in (43 cm). The anal fin is a few inches anterior to the tail and is white or pale blue, with 22-28 rays on it and a high, anterior lobe.[3] The pelvic fin is 6–12 in (15–30 cm) anterior to the tail fin. The gafftopsail catfish has maxillary barbels and one pair of barbels on the chin. It resembles the hardhead catfish, but its dorsal spine has a distinctive fleshy extension (like the fore-and-aft topsail of a ship).

The primary food of juveniles is unidentifiable organic matter; the secondary food is fish, with smaller amounts from other trophic groups. Unlike many other catfish, which are primarily bottom feeders, the gafftopsail catfish feeds throughout the water column. It eats mostly crustaceans, including crabs, shrimp, and prawns (95% of the diet), but it will also eat worms, other invertebrates, and bony fishes (about 5% of the diet).[4] In addition to humans, predators of the gafftopsail catfish include the tiger shark and bull shark.

Gafftopsail catfish spawn over inshore mudflats during a relatively short time span (10 days) from May to August;[5] they are mouthbreeders. The eggs are about 1 in (2.5 cm) in diameter. Males keep up to 55 eggs in their mouths until they hatch. Young are about 5 cm (2 inches) long when they hatch, and the male may continue to brood them until they are up to 4 in (10 cm) long. The males do not feed while they are carrying the eggs or young.[6]

Fishing

The gafftopsail catfish is a common catch in the Southeastern United States, although it is also caught as far north as New York. They are taken from piers, jetties, reefs, and the surf, as well as bottom fishing or flats fishing. They are caught with lures such as plugs, spoons, spinners, cut bait, and shrimp, as well as soft plastic lure resembling shrimp, worms, and shad. They are attracted to the sound of struggling fish, like a popping cork creates. Catfish trapping is also used to capture them, but is regulated in some states. Catfish traps include “slat traps,” long wooden traps with an angled entrance, and wire hoop traps. Typical bait for these traps includes rotten cheese and dog food.

Gafftopsail catfish are good eating; the red lateral line should be removed to prevent “muddy taste”; however in Gafftopsail taken from southern Florida mangrove estuaries, this is seemingly unnecessary. The pectoral fins and dorsal fin contain poisonous spines; care should be used when handling this fish.

Weight and length

Growth chart

The largest recorded weight for a gafftopsail catfish is 4.5 kg (9.9 lb)[7] and 69 cm (27 in) in length.[8] A more common weight and length of gafftopsails caught is 1–2 lb (450–910 g) and 12–16 in (30–41 cm).

As gafftopsail catfish grow longer, they increase in weight, but the relationship is not linear. The relationship between total length (L, in inches) and total weight (W, in pounds) for nearly all species of fish can be expressed by an equation of the form:

W = c L b {\displaystyle W=cL^{b}\!\,} W=cL^{b}\!\,

Invariably, b is close to 3.0 for all species, and the constant ct varies between species.[9] Data from the Florida Fish and Wildlife Conservation Commission indicate, for the gafftopsail catfish, c = 0.000493 and b = 3.075[10] The relationship described in this section suggests a 12-inch gafftopsail catfish will weigh about one pound, while a 20-inch fish will likely weigh about five pounds.

References

  1. ^ a b c Chao, L., Vega-Cendejas, M., Tolan, J., Jelks, H. & Espinosa-Perez, H. (2015). "Bagre marinus". IUCN Red List of Threatened Species. Version 2017.1. International Union for Conservation of Nature. Retrieved 18 February 2017. CS1 maint: Multiple names: authors list (link)
  2. ^ Gulf-topsail Cat, Felichthys felis (L.)
  3. ^ 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, pp. 85 & 346
  4. ^ FishBase.org: Food and Feeding Habits Summary - Bagre Marinus see online accessed 11 March 2010
  5. ^ Muncy R.J., Wingo W.M.,Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (Gulf of Mexico): Sea Catfish and Gafftopsail Catfish read online p. 4
  6. ^ Smith, pp. 85 & 346
  7. ^ IGFA 2007 Database of IGFA angling records. IGFA, Ft. Lauderdale, FL, USA http://www.igfa.org/Records/Fish-Records.aspx?Fish=Catfish, gafftopsail&LC=ATR
  8. ^ Froese, Rainer and Pauly, Daniel, eds. (2017). "Bagre marinus" in FishBase. February 2017 version.
  9. ^ 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.
  10. ^ average of data for male and female gafftopsail catfish at Florida Fish and Wildlife Conservation Commission Report 2008 accessed 7 March 2010
source: http://en.wikipedia.org/wiki/Gafftopsail_catfish

Mexican Free-tailed Bat 2

Mexican Free-tailed Bat 2 by Inked Animal

Mexican Free-tailed Bat  | Tadarida brasiliensis

 

We found this Mexican Free-tailed bat, aka Brazilian Free-tailed bat, in Austin, Texas.  There are tons of these in the city under bridges and roof eves, Austin is known for the colony under the Congress bridge, which is apparently one of the biggest, if not the biggest, urban bat colonies in the world.  They are pretty impressive.

Mexican Free-tailed Bat info via Wikipedia:

Mexican free-tailed bat
Tadarida brasiliensis
Tadarida brasiliensis.jpg
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Chiroptera
Family: Molossidae
Genus: Tadarida
Species: T. brasiliensis
Binomial name
Tadarida brasiliensis
(I. Geoffroy, 1824)
Subspecies
  • T. b. antillularum
  • T. b. bahamensis
  • T. b. brasiliensis
  • T. b. constanzae
  • T. b. cynocephali
  • T. b. intermedia
  • T. b. mexicana
  • T. b. murina
  • T. b. muscula
Tadarida brasiliensis Range.png
Range of the Mexican free-tailed bat

The Mexican free-tailed bat or Brazilian free-tailed bat (Tadarida brasiliensis) is a medium-sized bat that is native to the Americas, regarded as one of the most abundant mammals in North America. Its proclivity towards roosting in huge numbers at relatively few locations makes it vulnerable to habitat destruction in spite of its abundance. The bat is considered a species of special concern in California as a result of declining populations. It has been claimed to have the fastest horizontal speed (as opposed to e.g. stoop diving speed) of any animal, reaching top ground speeds of over 160 km/h; its actual air speed has not been measured.

Taxonomy

Molecular sequence data indicates T. brasiliensis's closest relatives are Chaerephon jobimena of Madagascar and Tadarida aegyptiaca of Africa and south Asia; the latter two are sister species. These three species form a clade believed to be about 9.8 million years old.[2]

Physical description

Mexican free-tailed bats are on average 9 cm (3.5 in) in length and weigh approximately 12.3 g (0.43 oz). The average wingspan is 28 cm (11 in).[3] Their tail is almost half their total length and stretches beyond the uropatagium, giving them the name "free-tailed" bats. Their ears are relatively close behind the muzzle and eyes; they are wide and set apart to help them find prey using echolocation. The muzzle is condensed, with wrinkled upper lips. The wings are elongated and narrow with pointed tips, making them well-equipped for quick, straight flight patterns. Their fur color ranges from dark brown to gray.

Range and ecology

Bats flying near Frio Cave in Concan, Texas

The Mexican free-tailed bat ranges from the southern half of the continental United States through most of Mexico, and through most of Central America into South America. The range of the Mexican free-tailed bat in South America is less understood where it lives in the eastern Brazilian highlands and coast, the northeastern Andes and the coast of Peru and northern Chile.[4] It is absent in much of the Amazon rainforest. The bat is also found in the Caribbean, and is native to all of the Greater Antilles and 11 of the Lesser Antilles.[5] The largest known colony is found at Bracken Cave, north of San Antonio, Texas, with nearly 20 million bats; research indicates the bats from this colony congregate in huge numbers at altitudes between 180 and 1,000 m (590 and 3,280 ft), and even as high as 3,000 m (9,800 ft).

Habitat

Mexican free-tailed bats roost primarily in caves. However, they will also roost in buildings of any type as long as they have access to openings and dark recesses in ceilings or walls.[4] The bats can make roosting sites of buildings regardless of "age, height, architecture, construction materials, occupancy by humans and compass orientation".[4] Caves, on the other hand, need to have enough wall and ceiling space to fit millions of bats.[4] Before buildings, free-tailed bats in the southeastern United States probably roosted in the hollows of trees such as red mangrove, black mangrove, white mangrove and cypress. However, most bats in Florida seem to prefer buildings and other man-made structures over natural roosts.[4] Caves in Florida tend to be occupied mostly by the southeastern myotis. Caves in Florida tend to have pools of water on the floor and the free-tailed bats do not need as much relative humidity as the southeastern myotis.[4]

Migration

Mexican free-tailed bats, emerging from Carlsbad Caverns, Carlsbad Caverns National Park, New Mexico

Mexican free-tailed bats in southeastern Nevada, southwestern Utah, western Arizona and southeastern California come together to migrate southwest to southern California and Baja California.[4] Bats in southeastern Utah, southwestern Colorado, western New Mexico and eastern Arizona travel though western edge of the Sierra Madre Oriental into Jalisco, Sinaloa and Sonora. Some bats that summer in Kansas, Oklahoma, eastern New Mexico and Texas will migrate southward to southern Texas[6] and Mexico.[4] Some bat populations in other areas of North America do not migrate, but are residents and may make seasonal changes in roost sites.[4]

Dusk emergence of bats at the Congress Avenue Bridge in Austin, Texas, U.S.

In Austin, Texas, a colony of Mexican free-tailed bats summers (they winter in Mexico) under the Congress Avenue Bridge ten blocks south of the Texas State Capitol. It is the largest urban colony in North America, with an estimated 1,500,000 bats.[7] Each night they eat 10,000 to 30,000 lb (4,500 to 13,600 kg) of insects. Each year they attract 100,000 tourists who come to watch them. In Houston, Texas, a colony is living under the Waugh Street Bridge over Buffalo Bayou. It is the home to 250,000 bats and also attracts viewers. The Mexican free-tailed bat is the official "flying mammal" of the state of Texas.[8]

Bats ranging eastward from East Texas do not migrate, but local shifts in roost usage often occur seasonally.[4] Also, a regional population that ranges from Oregon to California, has a year-round residence.

Diet

The Mexican free-tailed bat features in the logo of the Bacardi company

Mexican free-tailed bats are primarily insectivores. They hunt their prey using echolocation. The bats eat moths, beetles, dragonflies, flies, true bugs, wasps, and ants. Bats usually catch flying prey in flight.[9] Large numbers of Mexican free-tailed bats fly hundreds of meters above the ground in Texas to feed on migrating insects.[10] The consumption of insects by these bats can be quite significant.[11][12]

Health and mortality

One individual bat was recorded to have lived eight years, based on dentition.[13] Predators of the bat include large birds such as red-tailed hawk, American kestrels, great horned owls, barn owls, and Mississippi kites.[4][14] Mammal predators include Virginia opossums, striped skunks, and raccoons.[4] Snakes such as eastern coachwhips and eastern coral snakes may also prey on them, but at a lesser extent. Certain types of beetles prey on neonate and juvenile bats that have fallen to the ground.[4] This species seems to have a low incidence of rabies, at least in the United States.[4] They do, however, contain certain pesticides.[4]

Behavior

A male displays and sings in the presence of females (watch in slow motion).

Mexican free-tailed bats are nocturnal foragers and begin feeding after dusk. They travel 50 km in a quick, direct flight pattern to feed. This species flies the highest among bats, at altitudes around 3300 m.[15] Bats appears to be most active in late morning and afternoon between June and September.[16] Free-tailed bats are more active in warm weather.[17]

The species has been measured at a ground speed of 160 kilometres per hour (99 mph), measured by an aircraft tracking device.[18] The measurement methodology did not simultaneously record wind speed and ground speed, so the observations could have been affected by strong local gusts, and the bat's maximum air speed remains uncertain.[19]

Echolocation

Mexican free-tailed bats use echolocation for navigation and detecting prey. Traveling calls are of a brief but constant frequency. However, they switch modulated frequency calls between 40 and 75 kHz if they detect something.[20] Typically, the frequency range of their echolocation is between 49 and 70 kHz, but can be between 25 and 40 kHz if something crosses their path while in flight.[20]

On 6 November 2014, Aaron Corcoran, a biologist at Wake Forest University, North Carolina, reported online in Science that he and his team had detected Mexican free-tailed bats emitting ultrasonic vocalizations which had the effect of jamming the echolocation calls of a rival bat species hunting moths. The ‘jamming’ call led to an increased chance of the rival missing its prey, which the Mexican free-tailed bat was then able to eat itself. Earlier researchers had discovered some 15 types of social calls made by Mexican free-tailed bats and reported that they could adjust their calls to avoid interfering with others in range of their calls.[21][22]

Mating and reproduction

Free-tailed bats roosting at a cave in the Bahamas

During the breeding season, females aggregate into maternity roosts. The size of these roosts depends on the environment, with caves having the larger roosts. Mating can occur in an aggressive or passive form. In the aggressive form, the male controls the female's movements, keeping her away from the other bats in the roost.[23] He also tends to vocalize when mating. During passive copulation, the males simply flies to a female in her roost and quietly mounts her with no resistance. This species is a promiscuous breeder and both sexes copulate with multiple partners.[23] Females become sexually mature at about 9 months, while males take even longer, at two years. Females enter estrus once a year, which typically lasts five weeks in the spring. The gestation period of the bat lasts 11–12 weeks, with only one young being born. A number of pups are left in "creches", while their mothers roost elsewhere. The female uses vocalizations and scent to identify her pup. The mother imprints her scent on the young early on.[24] However, young try to steal a suckle from any female that passes through the cluster. A mother will nurse her young daily, and by 4–7 weeks old they are full grown, fully weaned, and independent.[25]

Protection

Though abundant and widespread, some local populations have prompted protection and conservation efforts. For instance, during the spring and summer, one of the largest Mexican free-tailed bat populations inhabits Cueva de la Boca, a cave near Monterrey, Mexico. In 2006, the Mexican environmental conservation NGO, Pronatura Noreste, purchased the property. Because of a reduction of more than 95% of the original 20 million bat population, as a result of vandalism, pollution, and uncontrolled tourism, the organization decided to buy the property to place it under conservation. Other species of high ecological value that inhabit the cavern are also being protected.

See also

  • Bat bomb, an experimental incendiary weapon that used Mexican free-tailed bats as a dispersal mechanism

References

  1. ^ Barquez, R., Diaz, M., Gonzalez, E., Rodriguez, A., Incháustegui, S. & Arroyo-Cabrales, J. (2015). Tadarida brasiliensis. The IUCN Red List of Threatened Species doi:10.2305/IUCN.UK.2015-4.RLTS.T21314A22121621.en
  2. ^ Lamb, J. M.; Ralph, T. M. C.; Naidoo, T.; Taylor, P. J.; Ratrimomanarivo, F.; Stanley, W. T.; Goodman, S. M. (June 2011). "Toward a Molecular Phylogeny for the Molossidae (Chiroptera) of the Afro-Malagasy Region". Acta Chiropterologica. 13 (1): 1–16. doi:10.3161/150811011X578589. 
  3. ^ "Animal Diversity Web: Tadarida brasiliensis". Retrieved 2016-11-10. 
  4. ^ a b c d e f g h i j k l m n o Wilkins, K. (1989). "Tadarida brasiliensis" (PDF). Mammalian Species. 331: 1–10. 
  5. ^ Baker, R. J., Genoways, H. H. (1978). "Zoogeography of Antillean bats", pp. 53–97 in Zoogeography in the Caribbean, F. B. Gill (ed.). Philadelphia: Acad
  6. ^ Glass BP (1982). "Seasonal movements of Mexican free-tail bats Tadarida brasiliensis mextcana banded in the Great Plains". Southwestern Nat. 27: 127–133. 
  7. ^ "Congress Avenue Bridge". Congress Avenue Bridge Bat Colony. Archived from the original on 12 November 2008. CS1 maint: BOT: original-url status unknown (link)
  8. ^ "Texas State Symbols". Texas State Library and Archives Commission. 
  9. ^ McWilliams, Lisa A. (2005). "Variation in Diet of the Mexican Free-Tailed Bat (Tadarida brasiliensis mexicana)". Journal of Mammalogy. 86 (3): 599. doi:10.1644/1545-1542(2005)86[599:VIDOTM]2.0.CO;2. 
  10. ^ McCracken, G. F.; Gillam, E. H.; Westbrook, J. K.; Lee, Y. F.; Jensen, M. L.; Balsley, B. B. (2008). "Brazilian free-tailed bats (Tadarida brasiliensis: Molossidae, Chiroptera) at high altitude: Links to migratory insect populations". Integrative and Comparative Biology. 48 (1): 107–18. doi:10.1093/icb/icn033. PMID 21669777. 
  11. ^ Corrigan, Robert. Do Bats Control Mosquitoes? texasmosquito.org
  12. ^ Animal Fact Sheet: Mexican Free-Tailed Bat. Desert Museum
  13. ^ Gannon, M., A. Kurta, A. Rodriquez-Duran, M. Willig. (2005). Bats of Puerto Rico. Jamaica. The University of the West Indies Press.
  14. ^ Mikula, P.; Morelli, F.; Lučan, R. K.; Jones, D. N.; Tryjanowski, P. (2016). "Bats as prey of diurnal birds: a global perspective". Mammal Review. 46 (3): 160. doi:10.1111/mam.12060. 
  15. ^ Williams, T. C.; Ireland, L. C.; Williams, J. M. (1973). "High Altitude Flights of the Free-Tailed Bat, Tadarida brasiliensis, Observed with Radar". Journal of Mammalogy. 54 (4): 807. doi:10.2307/1379076. JSTOR 1379076. 
  16. ^ Svoboda, P. L.; Choate, J. R. (1987). "Natural History of the Brazilian Free-Tailed Bat in the San Luis Valley of Colorado". Journal of Mammalogy. 68 (2): 224. doi:10.2307/1381461. JSTOR 1381461. 
  17. ^ Allen, L. C.; Turmelle, A. S.; Mendonça, M. T.; Navara, K. J.; Kunz, T. H.; McCracken, G. F. (2009). "Roosting ecology and variation in adaptive and innate immune system function in the Brazilian free-tailed bat (Tadarida brasiliensis)" (PDF). Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology. 179 (3): 315–23. doi:10.1007/s00360-008-0315-3. PMID 19002470. 
  18. ^ McCracken, Gary F.; Safi, Kamran; Kunz, Thomas H.; Dechmann, Dina K. N.; Swartz, Sharon M.; Wikelski, Martin (9 November 2016). "Airplane tracking documents the fastest flight speeds recorded for bats". Royal Society Open Science. 3 (11): 160398. doi:10.1098/rsos.160398. 
  19. ^ Photopoulos, Julianna (9 November 2016). "Speedy bat flies at 160km/h, smashing bird speed record". New Scientist. Retrieved 11 November 2016. But not everyone is convinced. Graham Taylor at the University of Oxford says that errors in estimating bat speed by measuring the distance moved between successive positions could be huge. “So I think it would be premature to knock birds off their pedestal as nature's fastest fliers just yet,” he says."These bats are indeed flying very fast at times, but this is based on their ground speed," says Anders Hedenström at the University of Lund in Sweden. "Since they did not measure winds at the place and time where the bats are flying, one can therefore not exclude that the top speeds are not bats flying in a gust." 
  20. ^ a b Gillam, Erin H.; McCracken, Gary F. (2007). "Variability in the echolocation of Tadarida brasiliensis: Effects of geography and local acoustic environment". Animal Behaviour. 74 (2): 277. doi:10.1016/j.anbehav.2006.12.006. 
  21. ^ Morell, Virginia (6 November 2014). "Holy blocked bat signal! Bats jam each other's calls". new.sciencemag.org. Retrieved 8 November 2014. 
  22. ^ Hogenboom, Melissa (7 November 2014). "Bats sabotage rivals' senses with sound in food race". BBC News. Retrieved 8 November 2014. 
  23. ^ a b Keeley, Annika T. H.; Keeley, Brian W. (2004). "The Mating System of Tadarida brasiliensis (Chiroptera: Molossidae) in a Large Highway Bridge Colony". Journal of Mammalogy. 85: 113. doi:10.1644/BME-004. 
  24. ^ Loughry, W. J.; McCracken, G. F. (1991). "Factors Influencing Female-Pup Scent Recognition in Mexican Free-Tailed Bats". Journal of Mammalogy. 72 (3): 624. doi:10.2307/1382150. JSTOR 1382150. 
  25. ^ Kunz, Thomas H.; Robson, Simon K. (1995). "Postnatal Growth and Development in the Mexican Free-Tailed Bat (Tadarida brasiliensis mexicana): Birth Size, Growth Rates, and Age Estimation" (PDF). Journal of Mammalogy. 76 (3): 769. doi:10.2307/1382746. JSTOR 1382746. 
source: http://en.wikipedia.org/wiki/Mexican_Free-tailed_Bat

Mexican Free-tailed Bat 1

Mexican Free-tailed Bat, Tadarida brasiliensis by Inked Animal

Mexican Free-tailed Bat  | Tadarida brasiliensis

We found this Mexican Free-tailed bat, aka Brazilian Free-tailed bat, in Austin, Texas.  There are tons of these in the city under bridges and roof eves, Austin is known for the colony under the Congress bridge, which is apparently one of the biggest, if not the biggest, urban bat colonies in the world.  They are pretty impressive.

   


Mexican Free-tailed Bat info via Wikipedia:

Mexican free-tailed bat
Tadarida brasiliensis
Tadarida brasiliensis.jpg
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Chiroptera
Family: Molossidae
Genus: Tadarida
Species: T. brasiliensis
Binomial name
Tadarida brasiliensis
(I. Geoffroy, 1824)
Subspecies
  • T. b. antillularum
  • T. b. bahamensis
  • T. b. brasiliensis
  • T. b. constanzae
  • T. b. cynocephali
  • T. b. intermedia
  • T. b. mexicana
  • T. b. murina
  • T. b. muscula
Tadarida brasiliensis Range.png
Range of the Mexican free-tailed bat

The Mexican free-tailed bat or Brazilian free-tailed bat (Tadarida brasiliensis) is a medium-sized bat that is native to the Americas, regarded as one of the most abundant mammals in North America. Its proclivity towards roosting in huge numbers at relatively few locations makes it vulnerable to habitat destruction in spite of its abundance. The bat is considered a species of special concern in California as a result of declining populations. It has been claimed to have the fastest horizontal speed (as opposed to e.g. stoop diving speed) of any animal, reaching top ground speeds of over 160 km/h; its actual air speed has not been measured.

Taxonomy

Molecular sequence data indicates T. brasiliensis's closest relatives are Chaerephon jobimena of Madagascar and Tadarida aegyptiaca of Africa and south Asia; the latter two are sister species. These three species form a clade believed to be about 9.8 million years old.[2]

Physical description

Mexican free-tailed bats are on average 9 cm (3.5 in) in length and weigh approximately 12.3 g (0.43 oz). The average wingspan is 28 cm (11 in).[3] Their tail is almost half their total length and stretches beyond the uropatagium, giving them the name "free-tailed" bats. Their ears are relatively close behind the muzzle and eyes; they are wide and set apart to help them find prey using echolocation. The muzzle is condensed, with wrinkled upper lips. The wings are elongated and narrow with pointed tips, making them well-equipped for quick, straight flight patterns. Their fur color ranges from dark brown to gray.

Range and ecology

Bats flying near Frio Cave in Concan, Texas

The Mexican free-tailed bat ranges from the southern half of the continental United States through most of Mexico, and through most of Central America into South America. The range of the Mexican free-tailed bat in South America is less understood where it lives in the eastern Brazilian highlands and coast, the northeastern Andes and the coast of Peru and northern Chile.[4] It is absent in much of the Amazon rainforest. The bat is also found in the Caribbean, and is native to all of the Greater Antilles and 11 of the Lesser Antilles.[5] The largest known colony is found at Bracken Cave, north of San Antonio, Texas, with nearly 20 million bats; research indicates the bats from this colony congregate in huge numbers at altitudes between 180 and 1,000 m (590 and 3,280 ft), and even as high as 3,000 m (9,800 ft).

Habitat

Mexican free-tailed bats roost primarily in caves. However, they will also roost in buildings of any type as long as they have access to openings and dark recesses in ceilings or walls.[4] The bats can make roosting sites of buildings regardless of "age, height, architecture, construction materials, occupancy by humans and compass orientation".[4] Caves, on the other hand, need to have enough wall and ceiling space to fit millions of bats.[4] Before buildings, free-tailed bats in the southeastern United States probably roosted in the hollows of trees such as red mangrove, black mangrove, white mangrove and cypress. However, most bats in Florida seem to prefer buildings and other man-made structures over natural roosts.[4] Caves in Florida tend to be occupied mostly by the southeastern myotis. Caves in Florida tend to have pools of water on the floor and the free-tailed bats do not need as much relative humidity as the southeastern myotis.[4]

Migration

Mexican free-tailed bats, emerging from Carlsbad Caverns, Carlsbad Caverns National Park, New Mexico

Mexican free-tailed bats in southeastern Nevada, southwestern Utah, western Arizona and southeastern California come together to migrate southwest to southern California and Baja California.[4] Bats in southeastern Utah, southwestern Colorado, western New Mexico and eastern Arizona travel though western edge of the Sierra Madre Oriental into Jalisco, Sinaloa and Sonora. Some bats that summer in Kansas, Oklahoma, eastern New Mexico and Texas will migrate southward to southern Texas[6] and Mexico.[4] Some bat populations in other areas of North America do not migrate, but are residents and may make seasonal changes in roost sites.[4]

Dusk emergence of bats at the Congress Avenue Bridge in Austin, Texas, U.S.

In Austin, Texas, a colony of Mexican free-tailed bats summers (they winter in Mexico) under the Congress Avenue Bridge ten blocks south of the Texas State Capitol. It is the largest urban colony in North America, with an estimated 1,500,000 bats.[7] Each night they eat 10,000 to 30,000 lb (4,500 to 13,600 kg) of insects. Each year they attract 100,000 tourists who come to watch them. In Houston, Texas, a colony is living under the Waugh Street Bridge over Buffalo Bayou. It is the home to 250,000 bats and also attracts viewers. The Mexican free-tailed bat is the official "flying mammal" of the state of Texas.[8]

Bats ranging eastward from East Texas do not migrate, but local shifts in roost usage often occur seasonally.[4] Also, a regional population that ranges from Oregon to California, has a year-round residence.

Diet

The Mexican free-tailed bat features in the logo of the Bacardi company

Mexican free-tailed bats are primarily insectivores. They hunt their prey using echolocation. The bats eat moths, beetles, dragonflies, flies, true bugs, wasps, and ants. Bats usually catch flying prey in flight.[9] Large numbers of Mexican free-tailed bats fly hundreds of meters above the ground in Texas to feed on migrating insects.[10] The consumption of insects by these bats can be quite significant.[11][12]

Health and mortality

One individual bat was recorded to have lived eight years, based on dentition.[13] Predators of the bat include large birds such as red-tailed hawk, American kestrels, great horned owls, barn owls, and Mississippi kites.[4][14] Mammal predators include Virginia opossums, striped skunks, and raccoons.[4] Snakes such as eastern coachwhips and eastern coral snakes may also prey on them, but at a lesser extent. Certain types of beetles prey on neonate and juvenile bats that have fallen to the ground.[4] This species seems to have a low incidence of rabies, at least in the United States.[4] They do, however, contain certain pesticides.[4]

Behavior

A male displays and sings in the presence of females (watch in slow motion).

Mexican free-tailed bats are nocturnal foragers and begin feeding after dusk. They travel 50 km in a quick, direct flight pattern to feed. This species flies the highest among bats, at altitudes around 3300 m.[15] Bats appears to be most active in late morning and afternoon between June and September.[16] Free-tailed bats are more active in warm weather.[17]

The species has been measured at a ground speed of 160 kilometres per hour (99 mph), measured by an aircraft tracking device.[18] The measurement methodology did not simultaneously record wind speed and ground speed, so the observations could have been affected by strong local gusts, and the bat's maximum air speed remains uncertain.[19]

Echolocation

Mexican free-tailed bats use echolocation for navigation and detecting prey. Traveling calls are of a brief but constant frequency. However, they switch modulated frequency calls between 40 and 75 kHz if they detect something.[20] Typically, the frequency range of their echolocation is between 49 and 70 kHz, but can be between 25 and 40 kHz if something crosses their path while in flight.[20]

On 6 November 2014, Aaron Corcoran, a biologist at Wake Forest University, North Carolina, reported online in Science that he and his team had detected Mexican free-tailed bats emitting ultrasonic vocalizations which had the effect of jamming the echolocation calls of a rival bat species hunting moths. The ‘jamming’ call led to an increased chance of the rival missing its prey, which the Mexican free-tailed bat was then able to eat itself. Earlier researchers had discovered some 15 types of social calls made by Mexican free-tailed bats and reported that they could adjust their calls to avoid interfering with others in range of their calls.[21][22]

Mating and reproduction

Free-tailed bats roosting at a cave in the Bahamas

During the breeding season, females aggregate into maternity roosts. The size of these roosts depends on the environment, with caves having the larger roosts. Mating can occur in an aggressive or passive form. In the aggressive form, the male controls the female's movements, keeping her away from the other bats in the roost.[23] He also tends to vocalize when mating. During passive copulation, the males simply flies to a female in her roost and quietly mounts her with no resistance. This species is a promiscuous breeder and both sexes copulate with multiple partners.[23] Females become sexually mature at about 9 months, while males take even longer, at two years. Females enter estrus once a year, which typically lasts five weeks in the spring. The gestation period of the bat lasts 11–12 weeks, with only one young being born. A number of pups are left in "creches", while their mothers roost elsewhere. The female uses vocalizations and scent to identify her pup. The mother imprints her scent on the young early on.[24] However, young try to steal a suckle from any female that passes through the cluster. A mother will nurse her young daily, and by 4–7 weeks old they are full grown, fully weaned, and independent.[25]

Protection

Though abundant and widespread, some local populations have prompted protection and conservation efforts. For instance, during the spring and summer, one of the largest Mexican free-tailed bat populations inhabits Cueva de la Boca, a cave near Monterrey, Mexico. In 2006, the Mexican environmental conservation NGO, Pronatura Noreste, purchased the property. Because of a reduction of more than 95% of the original 20 million bat population, as a result of vandalism, pollution, and uncontrolled tourism, the organization decided to buy the property to place it under conservation. Other species of high ecological value that inhabit the cavern are also being protected.

See also

  • Bat bomb, an experimental incendiary weapon that used Mexican free-tailed bats as a dispersal mechanism

References

  1. ^ Barquez, R., Diaz, M., Gonzalez, E., Rodriguez, A., Incháustegui, S. & Arroyo-Cabrales, J. (2015). Tadarida brasiliensis. The IUCN Red List of Threatened Species doi:10.2305/IUCN.UK.2015-4.RLTS.T21314A22121621.en
  2. ^ Lamb, J. M.; Ralph, T. M. C.; Naidoo, T.; Taylor, P. J.; Ratrimomanarivo, F.; Stanley, W. T.; Goodman, S. M. (June 2011). "Toward a Molecular Phylogeny for the Molossidae (Chiroptera) of the Afro-Malagasy Region". Acta Chiropterologica. 13 (1): 1–16. doi:10.3161/150811011X578589. 
  3. ^ "Animal Diversity Web: Tadarida brasiliensis". Retrieved 2016-11-10. 
  4. ^ a b c d e f g h i j k l m n o Wilkins, K. (1989). "Tadarida brasiliensis" (PDF). Mammalian Species. 331: 1–10. 
  5. ^ Baker, R. J., Genoways, H. H. (1978). "Zoogeography of Antillean bats", pp. 53–97 in Zoogeography in the Caribbean, F. B. Gill (ed.). Philadelphia: Acad
  6. ^ Glass BP (1982). "Seasonal movements of Mexican free-tail bats Tadarida brasiliensis mextcana banded in the Great Plains". Southwestern Nat. 27: 127–133. 
  7. ^ "Congress Avenue Bridge". Congress Avenue Bridge Bat Colony. Archived from the original on 12 November 2008. CS1 maint: BOT: original-url status unknown (link)
  8. ^ "Texas State Symbols". Texas State Library and Archives Commission. 
  9. ^ McWilliams, Lisa A. (2005). "Variation in Diet of the Mexican Free-Tailed Bat (Tadarida brasiliensis mexicana)". Journal of Mammalogy. 86 (3): 599. doi:10.1644/1545-1542(2005)86[599:VIDOTM]2.0.CO;2. 
  10. ^ McCracken, G. F.; Gillam, E. H.; Westbrook, J. K.; Lee, Y. F.; Jensen, M. L.; Balsley, B. B. (2008). "Brazilian free-tailed bats (Tadarida brasiliensis: Molossidae, Chiroptera) at high altitude: Links to migratory insect populations". Integrative and Comparative Biology. 48 (1): 107–18. doi:10.1093/icb/icn033. PMID 21669777. 
  11. ^ Corrigan, Robert. Do Bats Control Mosquitoes? texasmosquito.org
  12. ^ Animal Fact Sheet: Mexican Free-Tailed Bat. Desert Museum
  13. ^ Gannon, M., A. Kurta, A. Rodriquez-Duran, M. Willig. (2005). Bats of Puerto Rico. Jamaica. The University of the West Indies Press.
  14. ^ Mikula, P.; Morelli, F.; Lučan, R. K.; Jones, D. N.; Tryjanowski, P. (2016). "Bats as prey of diurnal birds: a global perspective". Mammal Review. 46 (3): 160. doi:10.1111/mam.12060. 
  15. ^ Williams, T. C.; Ireland, L. C.; Williams, J. M. (1973). "High Altitude Flights of the Free-Tailed Bat, Tadarida brasiliensis, Observed with Radar". Journal of Mammalogy. 54 (4): 807. doi:10.2307/1379076. JSTOR 1379076. 
  16. ^ Svoboda, P. L.; Choate, J. R. (1987). "Natural History of the Brazilian Free-Tailed Bat in the San Luis Valley of Colorado". Journal of Mammalogy. 68 (2): 224. doi:10.2307/1381461. JSTOR 1381461. 
  17. ^ Allen, L. C.; Turmelle, A. S.; Mendonça, M. T.; Navara, K. J.; Kunz, T. H.; McCracken, G. F. (2009). "Roosting ecology and variation in adaptive and innate immune system function in the Brazilian free-tailed bat (Tadarida brasiliensis)" (PDF). Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology. 179 (3): 315–23. doi:10.1007/s00360-008-0315-3. PMID 19002470. 
  18. ^ McCracken, Gary F.; Safi, Kamran; Kunz, Thomas H.; Dechmann, Dina K. N.; Swartz, Sharon M.; Wikelski, Martin (9 November 2016). "Airplane tracking documents the fastest flight speeds recorded for bats". Royal Society Open Science. 3 (11): 160398. doi:10.1098/rsos.160398. 
  19. ^ Photopoulos, Julianna (9 November 2016). "Speedy bat flies at 160km/h, smashing bird speed record". New Scientist. Retrieved 11 November 2016. But not everyone is convinced. Graham Taylor at the University of Oxford says that errors in estimating bat speed by measuring the distance moved between successive positions could be huge. “So I think it would be premature to knock birds off their pedestal as nature's fastest fliers just yet,” he says."These bats are indeed flying very fast at times, but this is based on their ground speed," says Anders Hedenström at the University of Lund in Sweden. "Since they did not measure winds at the place and time where the bats are flying, one can therefore not exclude that the top speeds are not bats flying in a gust." 
  20. ^ a b Gillam, Erin H.; McCracken, Gary F. (2007). "Variability in the echolocation of Tadarida brasiliensis: Effects of geography and local acoustic environment". Animal Behaviour. 74 (2): 277. doi:10.1016/j.anbehav.2006.12.006. 
  21. ^ Morell, Virginia (6 November 2014). "Holy blocked bat signal! Bats jam each other's calls". new.sciencemag.org. Retrieved 8 November 2014. 
  22. ^ Hogenboom, Melissa (7 November 2014). "Bats sabotage rivals' senses with sound in food race". BBC News. Retrieved 8 November 2014. 
  23. ^ a b Keeley, Annika T. H.; Keeley, Brian W. (2004). "The Mating System of Tadarida brasiliensis (Chiroptera: Molossidae) in a Large Highway Bridge Colony". Journal of Mammalogy. 85: 113. doi:10.1644/BME-004. 
  24. ^ Loughry, W. J.; McCracken, G. F. (1991). "Factors Influencing Female-Pup Scent Recognition in Mexican Free-Tailed Bats". Journal of Mammalogy. 72 (3): 624. doi:10.2307/1382150. JSTOR 1382150. 
  25. ^ Kunz, Thomas H.; Robson, Simon K. (1995). "Postnatal Growth and Development in the Mexican Free-Tailed Bat (Tadarida brasiliensis mexicana): Birth Size, Growth Rates, and Age Estimation" (PDF). Journal of Mammalogy. 76 (3): 769. doi:10.2307/1382746. JSTOR 1382746. 
source: http://en.wikipedia.org/wiki/Mexican_Free-tailed_Bat

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