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| '''Saltwater''' or '''estuarine crocodile''' (''Crocodylus porosus'') is the largest of all living ] and ]s. It is found in suitable habitat throughout ], ], and the surrounding waters |
'''Saltwater''' or '''estuarine crocodile''' (''Crocodylus porosus'') is the largest of all living ] and ]s. It is found in suitable habitat throughout ], ], and the surrounding waters. Saltwater crocodiles are known in the ] of ] as "salties". The ] are misnamed after the resemblance of the "saltie" to ]s as compared to ]s, which also inhabit the Northern Territory. | ||
| ==Anatomy and morphology== | ==Anatomy and morphology== | ||
Revision as of 19:29, 10 February 2009
| Saltwater Crocodile | |
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| Conservation status | |
 Least Concern (IUCN 2.3) | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Sauropsida |
| Order: | Crocodylia |
| Family: | Crocodylidae |
| Subfamily: | Crocodylinae |
| Genus: | Crocodylus |
| Species: | C. porosus |
| Binomial name | |
| Crocodylus porosus (Schneider, 1801) | |
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| Range of the saltwater crocodile in black | |
Saltwater or estuarine crocodile (Crocodylus porosus) is the largest of all living crocodilians and reptiles. It is found in suitable habitat throughout Southeast Asia, Northern Australia, and the surrounding waters. Saltwater crocodiles are known in the Northern Territory of Australia as "salties". The Alligator Rivers are misnamed after the resemblance of the "saltie" to alligators as compared to freshwater crocodiles, which also inhabit the Northern Territory.
Anatomy and morphology
The saltwater crocodile has a longer muzzle than the mugger crocodile, and is twice the length of its breadth at the base.
An adult male saltwater crocodile can usually grow 16 to 18 feet (4.9–5.5 m) and weigh about 1,400 to 2,500 pounds (640–1,130 kg) . Females are much smaller than males, with typical female body lengths in the range of 2.1 to 3 metres (6.9–9.8 ft). The largest female on record measured about 4.2 m (14 feet). The saltwater crocodile has fewer armor plates on its neck than other crocodilians, and its broad body contrasts with that of most other lean crocodiles, leading to early unverified assumptions that the reptile was an alligator.
The largest size saltwater crocodiles can reach is the subject of considerable controversy. The longest crocodile ever measured snout-to-tail and verified was the skin of a deceased crocodile, which was 6.2 metres (20 ft) long. Since skins tend to shrink slightly after removal from the carcass, this crocodile's living length was estimated at 6.3 metres (21 ft) and it probably weighed well over 1,200 kilograms (2,600 lb). Incomplete remains (the skull of a crocodile shot in Orissa) have been claimed to come from a 7.6 metres (25 ft) crocodile, but scholarly examination suggested a length no greater than 7 metres (23 ft). There have been numerous claims of crocodiles in the 9 metres (30 ft) range: the individual shot in the Bay of Bengal in 1840, reported at 10 metres (33 ft); another killed in 1823 at Jala Jala on Luzon reported at 8.2 metres (27 ft); a reported 7.6 metres (25 ft) crocodile killed in the Hooghly River in the Alipore District of Calcutta. However, examinations of these animals' skulls actually indicated animals ranging from 6 to 6.6 metres (20–22 ft).
With recent restoration in saltwater crocodile habitat and reduced poaching, it is possible that 7 metres (23 ft) or larger crocodiles are alive today. Guinness has accepted a claim of a 7 metres (23 ft) male saltwater crocodile, with an estimated weigh of 1,360 kilograms (3,000 lb), living within Bhitarkanika Park in the state of Orissa, India, although, due the near impossible task of taping and weighing a very large, live crocodile, the accuracy of these dimension has not been verified.
A crocodile shot in Queensland in 1957 was reported to be 8.5 metres (28 ft) long, but no verified measurements were made and no remains of this crocodile exist. A "replica" of this crocodile has been made as a tourist attraction. Many other unconfirmed reports of 8+ metres (26+ ft) crocodiles have been made but these are highly suspect.
Like all Crocodylians, salties' jaws are extremely powerful. On Discovery channel's Animal Face-Off, Dr. Adam Britton mentioned that he had measured the bite force of a 16ft saltie and got a reading of 3900lb. He also mentioned on the lion vs nile crocodile episode that the largest crocs on record could exert a bite pressure of over 4500lb. National Geographic's Brady Barr has measured the bite of a fully grown nile croc at 5000lb.
Distribution
Saltwater crocodiles are severely depleted in numbers throughout much of their range, and are virtually extinct in Thailand (a few individuals may persist in isolated national parks) and Vietnam (with the exception of occasional vagrants from Cambodia). In Cambodia they are known to exist in very small numbers within the countries rivers and mangroves. The status of this species is unknown within Myanmar (although given the recent fatal and ironic attack on a convict, they are definitely present within the Irrawaddy River) and they are known to exist in Bangladesh solely within the Sundarbans. Although Saltwater Crocodiles were once very common in the Mekong Delta (from which they disappeared in the 1980s) and other river systems, the future of this species in Southeast Asia is now looking grim, given the near non-existent population sizes in some countries. However, it is also the least likely of crocodilians to become globally extinct due to its wide distribution and almost pre-colonial population sizes in Northern Australia and New Guinea. In India this crocodile is extremely rare in most areas but is very common in the north eastern part of the country (mainly Orissa and the Sunderbans). The population is sporadic in Indonesia and Malaysia with some areas harboring large populations (Borneo, for example) and others with very small, "at risk" populations (e.g., the Philippines). The saltwater crocodile is also present in very limited parts of the South Pacific, with an average population in the Solomon Islands, a very small and soon to be extinct population in Vanuatu (where the population officially stands at only three) and a decent but at-risk population (which may be rebounding) in Palau. In northern Australia (which includes the top ends of the Northern Territory, Western Australia and Queensland) the Saltwater Crocodile is thriving, particularly in the multiple river systems near Darwin (such as the Adelaide, Mary and Daly Rivers, along with their adjacent billabongs and estuaries) where exceptionally large (6 meter +) individuals are not uncommon. A rough estimate states that the Australian Saltwater Crocodile population stands somewhere between 100,000 and 200,000 adults. Their range extends from Broome in Western Australia through the entire Northern Territory coast all the way down to Rockhampton in Queensland. In New Guinea they are also very common, existing within the coastal reaches of virtually every river system in the country, along with all estuaries and mangroves.
Saltwater crocodiles once ranged as far west as the east coast of Africa at the Seychelles Islands. These crocodiles were once believed to be a population of Nile crocodiles, but they were later proven to be Crocodylus porosus.
Habitat
Saltwater crocodiles generally spend the tropical wet season in freshwater swamps and rivers, moving downstream to estuaries in the dry season, and sometimes traveling far out to sea. Crocodiles compete fiercely with each other for territory, with dominant males in particular occupying the most eligible stretches of freshwater creeks and streams. Junior crocodiles are thus forced into the more marginal river systems and sometimes into the ocean. This explains the large distribution of the animal (ranging from the east coast of India to northern Australia) as well as its being found in odd places on occasion (such as the Sea of Japan). Saltwater crocodiles can swim 15 to 18 miles per hour in short bursts, but when cruising go 2 to 3 mph.
Diet & Behavior
The saltwater crocodile is an opportunistic apex predator capable of taking any animal that enters their territory, either in the water or on dry land. They have also been known to attack humans. Juveniles are restricted to smaller animals such as insects, amphibians, crustaceans, small reptiles and fish. The larger the animal grows, the greater the variety of animals it includes in the diet, although relatively small prey make up an important part of the diet even in adults. Large adult saltwater crocodiles can potentially eat any animal within its range, including monkeys, kangaroos, wild boar, dingos, goannas, birds, domestic livestock, pets, water buffalo, gaurs, great white sharks, tiger sharks, and humans, among other large animals as well. Domestic cattle, horse, water buffalo and gaur, all of which may weigh over a ton, are considered the largest prey taken by male crocodiles. The only threats to adult saltwater crocodiles are other crocodiles. Generally very lethargic – a trait which helps it survive months at a time without food – it typically loiters in the water or basks in the sun through much of the day, preferring to hunt at night. Capable of explosive bursts of speed when launching an attack from the water, many species of crocodile are also capable of fast land-movement. Many crocodiles are capable of explosive charges that can carry them nearly as fast as a running human. The 23 species of crocodilian can travel over land using the belly crawl, the walk, the high-walk, and the gallop. However, stories of crocodiles being faster than a race horse for short distances across the ground are little more than urban legend.
As an ambush predator, it usually waits for its prey to get close to the water's edge before striking, using its great strength to drag the animal back into the water. Most prey animals are killed by the great jaw pressure of the crocodile, although some animals may be incidentally drowned. It is an immensely powerful animal, having the strength to drag a fully grown water buffalo into a river, or crush a full-grown bovid's skull between its jaws.
In its deadliest attack, called the "death roll," it grabs onto the animal and rolls powerfully. This is designed to initially throw any struggling large animal off balance making it easier to drag it into the water. The "death roll" is also used for tearing apart large animals once they are dead.
Attacks On Humans
Saltwater crocodiles are very dangerous animals, but data on attacks is limited outside of Australia, and estimates of human fatalities vary wildly between dozens to thousands annually. It is likely that, given this species low population within most of its non-Australian/New Guinean range, the number of attacks is probably within the lower range of estimates. Most attacks by adult "salties" are fatal, given the animals' size and strength. In Australia, attacks are rare and usually make headlines when they do occur. There are, on average, no more than one or two fatal attacks reported per year in the country. The low level of attacks is most likely due to the extensive effort by local wildlife officials to post crocodile "warning" signs at nearly every billabong, river, lake and even at some beaches and also due to the relatively well-informed nature of the local citizens. In the Aboriginal community of Arnhem Land, which occupies roughly half of the top end of the Northern Territory, attacks may go unreported and may be more common. The majority of "unreported" attacks most likely occur in New Guinea, where the species population is very high and precautions are few. There have also been recent, less public attacks in Borneo, Sumatra, eastern India and in Myanmar.
Intelligence
Dr. Adam Britton, a researcher with Big Gecko, has been studying crocodilian intelligence. In so doing, he has compiled a collection of Australian saltwater crocodile calls, and associated them with behaviors. His position is that while crocodilian brains are much smaller than those of mammals (as low as 0.05% of body weight in the saltwater crocodile), they are capable of learning difficult tasks with very little conditioning. He also infers that the crocodile calls hint at a deeper language ability than currently accepted. He suggests that saltwater crocodiles are clever animals that can possibly learn faster than lab rats. They have also learned to track the migratory route of their prey as the climate changes.
Bibliography
References
- Guggisberg, C.A.W. (1972). Crocodiles: Their Natural History, Folklore, and Conservation. p. 195. ISBN 0715352725.
- http://www.flmnh.ufl.edu/cnhc/csp_cpor.htm
- ^ 'Crocodylus porosus' (Schneider, 1801), by Adam Britton from the Crocodilian Species List.
- ADW: Crocodylus porosus: Information
- ^ Wood, The Guinness Book of Animal Facts and Feats. Sterling Pub Co Inc (1983), ISBN 978-0851122359
- ^ Which is the largest species of crocodile?
- ^ Guinness: India Park Home to World's Largest Crocodile; 23 Feet
- ^ Seven-metre maneating crocodile shot dead, Daily Telegraph
- World's Largest Reptile Found in India: Giant estuarine crocodile finds place in Guinness World Records
- NORMANTON - Home of largest Crocodile ever shot!
- Krys the crocodile, Normanton, Queensland
- <http://animals.nationalgeographic.com/animals/reptiles/saltwater-crocodile.html>
- Warm, fuzzy, weird, funny: The Museum(s) of Natural History spin some tall tales, Alvin Powell, Harvard Gazette
- Saltwater Crocodile at National Geographic
- http://www.msnbc.msn.com/id/24226179/
- No Bull: Saltwater Crocodile Eats Shark
- photograph of crocodile eating a shark
- Mother's tug-of-war with child-eating crocodile
- Crocodile Attack in Australia: An Analysis of Its Incidence and Review of the Pathology and Management of Crocodilian Attacks in General
Marshall, Ben "The Crocodile" New York Publishers Inc. 1999
See also
- Crocodile attack
- Crocodile farming in Iran
External links
- Recent Crocodile Attacks in Australia
- Australian Saltwater Crocodile Photos and attack file
- Saltwater crocodile calls from Dr. Britton's crocodilian.com site
- Brief discussion from Dr. Britton and others discussing dromaeosaurid intelligence
| Extant Crocodilian species | |||||||||||||||||
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| Related articles on alligators, caimans, crocodiles and gharials | |
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- IUCN Red List least concern species
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- Fauna of Cambodia
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- Fauna of Malaysia
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- Fauna of Papua New Guinea
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