American crocodile

American crocodile
American Crocodile
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Crocodilia
Family: Crocodylidae
Subfamily: Crocodylinae
Genus: Crocodylus
Species: C. acutus
Binomial name
Crocodylus acutus
(Cuvier, 1807)
Terrestrial range of Crocodylus acutus (green).
Synonyms

Crocodilus acutus Cuvier, 1807
Crocodilus americanus Cope, 1900

The American crocodile (Crocodylus acutus) is a species of crocodilian found in the Neotropics. It is the most widespread of the four extant species of crocodiles from the Americas. Populations occur from the Atlantic and Pacific coasts of southern Mexico to South America as far as Peru and Venezuela. It also lives within many river systems on Cuba, Jamaica, and Hispaniola. Within the United States the American crocodile is only found within the southern half of Florida. In Florida, there is an estimated population of about 2000. Despite its proximity to Hispaniola, the American crocodile is not found in Puerto Rico. The habitat of the American crocodile consists largely of coastal areas. The American crocodile is larger than some other crocodile species, with some males reaching lengths of 6.1 metres (20 ft) in Central and South America.

Contents

Description

An American crocodile hatchling in Colombia

Like all crocodilians, the American crocodile is a quadruped, with four short, splayed legs; a long, powerful tail; a scaly hide with rows of ossified scutes running down its back and tail.[2] The snout is elongated and includes a strong pair of jaws. The eyes have nictitating membranes for protection along with lachrymal glands, which produce tears.

The nostrils, eyes, and ears are situated on the top of its head, so the rest of the body can be concealed underwater for surprise attacks.[2] Camouflage also helps them prey on food. The snout is relatively longer and narrower than the American alligator although broader on average than the Orinoco crocodile.[3] American crocodiles are also paler and more grayish than the relatively dark-hued alligator. This crocodile species normally crawl on their belly, but they can also "high walk".[4] Larger specimens can charge up to 10 miles per hour (16 km/h).[5] They can swim at as much as 20 miles per hour (32 km/h) by moving their body and tail in a sinuous fashion, but they cannot sustain this speed.[6]

American crocodiles are more susceptible to cold than American alligators.[7] Unlike the American alligator which can subsist in water of 7.2 °C (45.0 °F) for some time, an American crocodile would become helpless and drown.[2] American crocodiles, however, have a faster growth rate than alligators, and are much more tolerant of salt water.[2]

Unlike the Old World crocodiles which are sometimes cleared of parasites by birds, the American crocodile relies more on fish for parasite removal.[2]

Size

Newborn hatchlings are about 22 centimetres (8.7 in) in size and about 60 grams (2 oz) in mass.[8][9] The average adult is 4 metres (13 ft) long and weighs 382 kilograms (840 lb) in males, and 3 metres (9.8 ft) and 173 kilograms (380 lb) in females.[10][11]

In the Tárcoles River in Costa Rica there are dozens of 4-meter and a few 5-meter individuals that frequent bridge crossings (where they are fed daily, which may have helped them reach such consistently large sizes) and are a popular tourist attraction. In their United States range, adult length has been recorded as high as 4.9 metres (16 ft) but adult males on average measure only 3.5 metres (11 ft) long.[8][12][13] This species is said to grow largest in the South American river basins, but even old males rarely reach 6 metres (20 ft).[12][14] A skull of this species was found to measure 72.6 centimetres (28.6 in) and is estimated to have belonged to a crocodile of 6.6 metres (22 ft) in length.[13] Large, mature males regularly weigh about 400–500 kg (880-1100 lb), with the 6 meter+ individuals surpassing 1000 kg (2,200 lb).[15] The longest American crocodile ever actually measured from snout to tail is a 17 feet (5.2 m) male living within the Tarcoles River of Costa Rica.[citation needed]

Diet

American crocodile's primary prey throughout life is fish and virtually any freshwater fish is potential prey. Prey species can range in size from the insects taken by young crocodiles to cattle taken by large adults and includes birds, mammals, turtles, crabs, snails, frogs, and occasionally carrion.[11][16] Adult American crocodile don't have any natural predators and are capable of eating anything at the water's edge.

Range and distribution

Crocodylus acutus in La Manzanilla, Jalisco, Mexico.

C. acutus is the most widespread of the four extant species of crocodiles from the Americas.[1] It inhabits waters such as mangrove swamps, river mouths, fresh waters, and salt lakes and can even be found at sea (hence its wide distribution on the Caribbean islands).[2] Southern Florida, the Greater Antilles and southern Mexico to Colombia and Ecuador.[8][16] The American crocodile is especially plentiful in Costa Rica.[17] One of the largest documented populations of American crocodiles is in Lago Enriquillo, a landlocked, hypersaline lake in the Dominican Republic.[11] The species has also been recorded from Jamaica.[18]

American crocodiles are saline tolerant, hence their wide distribution throughout the Caribbean. American crocodiles have recently been sighted in Grand Cayman, leading experts to believe that the species may be swimming from Cuba (which is home to a massive American crocodile population) and slowly repopulating Grand Cayman. In addition, an American crocodile/Cuban crocodile hybrid was recently discovered in the Cancun area. The crocodile likely originated in the Zapata Swamp of Cuba (the only place where these wild hybrids exist) and swam to the Yucatan Peninsula. This saline tolerance also allowed the American crocodile to colonize limited portions of the United States (only extreme southern Florida.) Contrary to popular misinformation, the presence of the American alligator is not the reason the American crocodile was unable to populate brackish waters north of Florida, but rather the climate. American crocodiles, unlike American alligators, are extremely susceptible to cold temperatures and live exclusively within tropical waters. During 2009 unusually cold weather within southern Florida resulted in the deaths of approximately 150 wild American crocodiles, including a well known crocodile which inhabited Sanibel Island far north of the crocodile's natural range.[19][20]

American crocodiles in the United States cohabit with the American alligator, and are primarily found in Everglades National Park, Florida Bay, Biscayne Bay and the Florida Keys from Miami southward.[7][9] A sizable population occurs near Homestead, Florida, at the Turkey Point Nuclear Generating Station.[9][21][22] Some individuals wander northward to warm summer waters and have been sighted in Sarasota County and Palm Beach County.[8] In the summer of 2008, a crocodile was captured in the surf on Isle of Palms, South Carolina.

Crocodiles require consistent tropical temperatures, hence their lack of distribution within the southern United States. They are saltwater-tolerant and have thus been capable of colonizing a multitude of islands within the Caribbean and on some coastal pacific islands as well. They co-exist with the smaller and less territorial American alligator within the Everglades National Park of southern Florida and with the very small Spectacled caiman within Central America. The only other crocodiles present within the American crocodile's range are the smaller and critically endangered Cuban Crocodile, along with the small Morelet's Crocodile in southern Mexico/Guatemala.

Systematics

Cuvier originally described the species as Crocodylus acutus in 1807.[23] Over time, it commonly became known as the "sharp-snout alligator". In 1822, Constantine Samuel Rafinesque postulated that the species was in fact a crocodile.[24]

The species was re-described as Crocodylus floridanus by William T. Hornaday in 1875,[25][26] when Hornaday and C.E. Jackson were sent from Washington, D.C. to Florida in order to collect alligator hides. Upon hearing of a "big old gator" in Arch Creek at the head of Biscayne Bay, Hornaday and his companions searched for it and reported:

"In a few hours we got sight of him, out on the bank in a saw-grass wallow. He was a monster for size–a perfect whale of a saurian, gray in color—and by all the powers, he was a genuine crocodile!"[27]

Crocodylus floridanus is now considered an invalid junior synonym of C. acutus.[28][29]

Conservation status

Due to hide hunting, pollution, loss of habitat, and removal of adults for commercial farming, the American crocodile is endangered in parts of its range.[9] In 1972, Venezuela banned commercial crocodile skin harvesting for a decade, as a result of 1950s and 1960s overhunting.[30]

One thousand to two thousand American crocodiles live in Mexico and Central and South America, but populations are data deficient.[11] The American crocodile is considered a vulnerable species, but has not been assessed since 1996.[1] It has an estimated wild population of 500 to 1,200 in southern Florida.[31] On March 20, 2007, the United States Fish and Wildlife Service declassified the American crocodile as an endangered species, downgrading its status to "threatened"; the reptile remains protected from illegal harassing, poaching or killing under the federal Endangered Species Act.[32][33] While not endangered, the American Alligator is also protected in the United States so that no crocodiles are killed by mistake.

Interaction with humans

American crocodiles can be dangerous to humans, and attacks in Mexico, Costa Rica, and Panama are not unprecedented. These attacks rarely make international news, and therefore this species is not as well-documented a man-eater as its relatives.[2] The species is reportedly timid, and seemingly lacks the propensity to attack humans as seriously as Old World crocodiles can.[24] In May 2007, there were two instances within one week of children being attacked and killed by this species—one in Mexico just south of Puerto Vallarta and one in Costa Rica.[34][35] No attacks on humans by the American crocodile have been reported in the United States, despite assorted anecdotes.[36]

References

  1. ^ a b c Crocodile Specialist Group (1996). Crocodylus acutus. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 7 December 2008. Listed as Vulnerable (VU A1ac v2.3)
  2. ^ a b c d e f g Guggisberg, C.A.W. (1972). Crocodiles: Their Natural History, Folklore, and Conservation. Newton Abbot: David & Charles. p. 195. ISBN 0-7153-5272-5. 
  3. ^ [1] (2011).
  4. ^ Gregg, Gordon; Gans,Carl (PDF). Morphology & Physiology of the Crocodylia. http://eprint.uq.edu.au/archive/00002011/02/croc.pdf. 
  5. ^ "American Crocodile". Rainforest Exploration. Earth's Birthday Project. http://www.earthsbirthday.org/explore/teachers/infocrocodile.htm. Retrieved 2008-12-12. [dead link]
  6. ^ "American Crocodile". Everglades. Miami Science Museum. http://www.miamisci.org/ecolinks/everglades/crocinfo.html. Retrieved 2008-12-12. 
  7. ^ a b Kushlan, JA; Mazotti, F (1989). "Historic and present distribution of the American crocodile in Florida.". Journal of Herpetology 23 (1): 1–7. doi:10.2307/1564309. JSTOR 1564309. 
  8. ^ a b c d Conant, Roger; Collins, Joseph T (1998). Reptiles and Amphibians Eastern-Central North America (3rd ed.). Boston: Houghton Mifflin. pp. 142–3. ISBN 0-395-90452-8. 
  9. ^ a b c d Moller, Michelle P.; Cherkiss, Michael S. Mazzotti, Frank J.. "The American Crocodile: A Story of Recovery". The Croc Docs. Fort Lauderdale Research and Education Center. http://crocdoc.ifas.ufl.edu/publications/posters/crocodilerecovery/. Retrieved 2008-12-12. 
  10. ^ Savage, Jay M.; Fogden, Michael; Fogden, Patricia (2005). The Amphibians and Reptiles of Costa Rica: A Herpetofauna between Two Continents, between Two Seas. University Of Chicago Press. ISBN 978-0-226-73538-2. 
  11. ^ a b c d "American Crocodile". Animals. National Geographic Society. http://animals.nationalgeographic.com/animals/reptiles/american-crocodile.html?nav=A-Z. Retrieved 2008-11-29. 
  12. ^ a b Behler JL, King FW. 1979. The Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Alfred A. Knopf. 743 pp. LCCCN 79-2217. ISBN 0-394-50824-6.
  13. ^ a b Wood, Gerald (1983). The Guinness Book of Animal Facts and Feats. p. 256. ISBN 978-0-85112-235-9. 
  14. ^ http://animals.nationalgeographic.com/animals/reptiles/american-crocodile.html
  15. ^ http://www.seaworld.org/Animal-info/animal-bytes/animalia/eumetazoa/coelomates/deuterostomes/chordata/craniata/reptilia/crocodylia/american-crocodile.htm
  16. ^ a b "American Crocodile (Crocodylus acutus)". Crocodilians: Natural History & Conservation. Florida Museum of Natural History. http://www.flmnh.ufl.edu/cnhc/csp_cacu.htm. Retrieved 2008-11-29. 
  17. ^ "8 Crocodiles kill man in Mexico". Sindh Today. 12 August 2008. Archived from the original on 2008-08-22. http://web.archive.org/web/20080822053412/http://www.sindhtoday.net/world/11409.htm. Retrieved 2008-11-29. 
  18. ^ Ahrenfeldt, Robert H. (1954-05-05). "Identification of the Amphibia and Reptilia Recorded in Jamaica growing rapidly by Hans Sloane (1688-89)". Copeia (American Society of Ichthyologists and Herpetologists) 1954 (2): 105–111. doi:10.2307/1440328. JSTOR 1440328. 
  19. ^ www.crocodilian.com
  20. ^ Dr. Adam Britton
  21. ^ "Providing a home for the American crocodile" (PDF). Florida Power & Light. http://www.fpl.com/environment/plant/pdf/turkey_point_crocodile_fact_sheet.pdf. 
  22. ^ Allen, Greg (21 April 2007). "American Crocodiles Make a Comeback". National Public Radio. http://www.npr.org/templates/story/story.php?storyId=9718547. Retrieved 2008-12-12. 
  23. ^ * "Crocodylus acutus". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=174361. Retrieved 24 December 2008. 
  24. ^ a b Levin, Ted (2004). Liquid Land: A Journey Through the Florida Everglades. University of Georgia Press. ISBN 0-8203-2672-0. 
  25. ^ Hornaday, William T.. "The crocodile in Florida". The American Naturalist 9. 
  26. ^ "A New Day Dawns in the Everglades". Audubon Magazine. July–August 2001. http://audubonmagazine.org/features0107/everglades_intro.html. Retrieved 2009-01-08. 
  27. ^ Hornaday, William T. (1925). A Wild-animal Round-up. C. Scribner's Sons. p. 147. http://books.google.com/?id=_00lAAAAMAAJ&q=%22whale+of+a+saurian%22. Retrieved 2008-12-28. 
  28. ^ * "Crocodylus floridanus". Integrated Taxonomic Information System. http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=209643. Retrieved 24 December 2008. 
  29. ^ Stejneger, Leonhard (1933-10-15). "Crocodilian Nomenclature". Copeia (American Society of Ichthyologists and Herpetologists) 1933 (3): 117–120. doi:10.2307/1436233. JSTOR 1436233. 
  30. ^ Pough, F. Harvey; Robin M. Andrews; John E. Cadle; Martha L. Crump; Alan H. Savitsky, Kentwood D. Wells (2004). Herpetology (3rd ed.). Upper Saddle River, New Jersey: Pearson/Prentice Hall. pp. 628–9. ISBN 0-13-100849-8. 
  31. ^ "American Crocodile (Crocodylus acutus)". National Parks Conservation Association. http://www.npca.org/marine_and_coastal/marine_wildlife/crocodile.html. Retrieved 2008-12-07. 
  32. ^ "U.S. Crocodiles Shed "Endangered" Status". National Geographic Society. 21 March 2007. http://news.nationalgeographic.com/news/pf/98669458.html. Retrieved 2008-12-07. 
  33. ^ American Crocodile No Longer Near Extinction. March 21, 2007.
  34. ^ "Boy killed in crocodile attack in Mexico". msnbc.com. Associated Press. 3 May 2007. http://www.msnbc.msn.com/id/18474361. Retrieved 2008-11-29. 
  35. ^ "Crocodile makes off with boy". Television New Zealand. Reuters. 5 May 2007. http://tvnz.co.nz/view/page/411749/1098603. Retrieved 2008-11-29. 
  36. ^ Langley, Ricky L. (2005). "Alligator Attacks on Humans in the United States" (PDF). Wilderness and Environmental Medicine 16 (3): 119–124. PMID 16209465. http://www.allenpress.com/pdf/weme_16_303_119_124.pdf. 

External links

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