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Size
Size greatly varies between species, from the dwarf crocodile to the saltwater crocodile. Species of Palaeosuchus and Osteolaemus grow to an adult size of just 1 metre (3.3 ft) to 1.5 metres (4.9 ft). Larger species can reach over 4.85 metres (15.9 ft) long and weigh well over 1,200 kilograms (2,600 lb). Crocodilians show pronounced sexual dimorphism with males growing much larger and more rapidly than females. Despite their large adult size, crocodiles start their life at around 20 centimetres (7.9 in) long. The largest species of crocodile is the saltwater crocodile, found in northern Australia, throughout south-east Asia, and in the surrounding waters.
Two larger certifiable records are both of 6.2 metres (20 ft) crocodiles. The first crocodile was shot in the Mary River in the Northern Territory of Australia in 1974 by poachers and measured by wildlife rangers. The second crocodile was killed in 1983 in the Fly River, Papua New Guinea. In the case of the second crocodile it was actually the skin that was measured by zoologist Jerome Montague, and as skins are known to underestimate the size of the actual animal, it is possible this crocodile was at least another 10 cm longer.
The largest crocodile ever held in captivity is an Estuarine–Siamese hybrid named Yai (Template:Lang-th, meaning big) (born 10 June 1972) at the famous Samutprakarn Crocodile Farm and Zoo, Thailand. This animal measures 6 m (19.69 ft) (19 ft 8 in) in length and weighs 1114.27 kg.
The largest captive crocodile alive in the US is located in South Carolina. In June 2002, Alligator Adventure introduced Utan. At 20 feet (6.1 m) long and weighing in at more than a ton, "Utan", the largest crocodile to ever be exhibited in the United States, made his new home in Myrtle Beach.
Wildlife experts, however, argue that the largest crocodile so far found in the Bhitarkanika was almost 23 feet (7.0 m) long, which could be traced from the skull preserved by the Kanika Royal Family. The crocodile was shot near Dhamara in 1926 and later its skull was preserved by the then Kanika King. Crocodile experts estimate the animal was between 20 feet (6.1 m) and 23 feet (7.0 m) long, as the size of the skull was measured one ninth of the total length of the body.
Age
There is no reliable way of measuring crocodile age, although several techniques are used to derive a reasonable guess. The most common method is to measure lamellar growth rings in bones and teeth—each ring corresponds to a change in growth rate which typically occurs once a year between dry and wet seasons. Bearing these inaccuracies in mind, the oldest crocodilians appear to be the largest species. C. porosus is estimated to live around 70 years on average, and there is limited evidence that some individuals may exceed 100 years. One of the oldest crocodiles recorded died in a zoo in Russia. A male freshwater crocodile at the Australia Zoo is estimated to be 130 years old. He was rescued from the wild by Bob Irwin and Steve Irwin after being shot twice by hunters. As a result of the shootings, this crocodile (known affectionately as "Mr. Freshy") has lost his right eye.
Skin
Crocodiles have smooth skin on their belly and side, while their dorsal surface is armoured with large osteoderms. The armoured skin has scales and is thick and rugged, providing some protection. They are still able to absorb heat through this thick, rugged armour as a network of small capillaries push blood through the scales to absorb heat.
Taxonomy of the Crocodylidae
Most species are grouped into the genus Crocodylus. The other extant genus, Osteolaemus, is monotypic (as is Mecistops, if recognized).
- Family Crocodylidae
- Subfamily †Mekosuchinae (extinct)
- Subfamily Crocodylinae
- Genus Crocodylus
- Crocodylus acutus, American Crocodile
- Crocodylus cataphractus, Slender-snouted Crocodile (studies in DNA and morphology suggest that this species may be more basal than Crocodylus, and therefore belongs in its own genus, Mecistops)
- Crocodylus intermedius, Orinoco Crocodile
- Crocodylus johnsoni, Freshwater Crocodile
- Crocodylus mindorensis, Philippine Crocodile
- Crocodylus moreletii, Morelet's Crocodile or Mexican Crocodile
- Crocodylus niloticus, Nile Crocodile or African Crocodile (the subspecies found in Madagascar is sometimes called the Black Crocodile)
- Crocodylus novaeguineae, New Guinea Crocodile
- Crocodylus palustris, Mugger Crocodile, Marsh Crocodile, or Indian Crocodile
- Crocodylus porosus, Saltwater Crocodile or Estuarine Crocodile
- Crocodylus rhombifer, Cuban Crocodile
- Crocodylus siamensis, Siamese Crocodile
- Genus Osteolaemus
- Osteolaemus tetraspis, Dwarf Crocodile (there has been controversy whether or not this is actually two species; current thinking is that there is one species with 2 subspecies: O. tetraspis tetraspis & O. t. osborni)
- Genus †Euthecodon
- Genus †Rimasuchus (formerly Crocodylus lloydi)
- Genus †Voay Brochu, 2007 (formerly Crocodylus robustus)
- Genus Crocodylus
Some of the extinct relatives of true crocodiles, members of the larger group Crocodylomorpha, were herbivorous.
Crocodiles and Humans
Danger to humans
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The larger species of crocodiles are very dangerous to humans. The main danger that crocodiles pose is not their ability to run after a person but their ability to strike before the person can react. The Saltwater and Nile Crocodiles are the most dangerous, killing hundreds of people each year in parts of south-east Asia and Africa. Mugger crocodiles and possibly the endangered Black Caiman are also very dangerous to humans. American alligators are less aggressive and rarely assault humans without provocation.
The most deaths in a single crocodile attack incident may have occurred during the Battle of Ramree Island, on February 19, 1945, in Burma. Nine hundred soldiers of an Imperial Japanese Army unit, in an attempt to retreat from the Royal Navy and rejoin a larger battalion of the Japanese infantry, crossed through 16 kilometres (9.9 mi) of mangrove swamps which contained Saltwater Crocodiles. Twenty Japanese soldiers were captured alive by the British, and almost five hundred are known to have escaped Ramree. Many of the remainder may have been eaten by the crocodiles, although gunfire from the British troops was undoubtedly a contributory factor..
Crocodile products
Main article: Crocodile farm
Crocodile leather can be made into goods such as wallets, briefcases, purses, handbags, belts, hats, and shoes.
Crocodile meat is consumed in some countries, such as Australia, Ethiopia, Thailand, South Africa and also Cuba (in pickled form); it can also be found in specialty restaurants in some parts of the United States. The meat is white and its nutritional composition compares favourably with that of other meats. It tends to have a slightly higher cholesterol level than other meats. Crocodile meat has a delicate flavour; some describe it as a cross between chicken and crab. Cuts of meat include backstrap and tail fillet.
See also
References
- Cite error: The named reference
ausfaunawas invoked but never defined (see the help page). - http://www.worldcrocodile.com/centerfarm.swf
- Britton Adam. Crocodilian Biology Database, FAQ. "How long do crocodiles live for?". Retrieved 9/11/2006.
- profile of Mr Freshy at Australia Zoo website, accessed 1 February 2007
- McAliley, Willis, Ray, White, Brochu & Densmore (2006). Are crocodiles really monophyletic?—Evidence for subdivisions from sequence and morphological data. Molecular Phylogenetics and Evolution 39:16-32.
Further reading
- Iskandar, DT (2000). Turtles and Crocodiles of Insular Southeast Asia and New Guinea. ITB, Bandung.
- Crocodilian Biology Database, FAQ. "How long do crocodiles live for?" [sic] Adam Britton.
- Crocodilian Biology Database, FAQ. "How fast can a crocodile run?" Adam Britton.
External links
- Crocodilian Online
- Crocodilian Biology Database
- Crocodile Attacks in Australia
- BBC news finds powerful agent in crocodile blood
- 90m years old fossils of crocodile found in Brazil
- Crocodylidae
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