Crocodile

A crocodile is any species belonging to the family Crocodylidae (sometimes classified instead as the subfamily Crocodylinae). The term can also be used more loosely to include all members of the order Crocodilia: i.e. the true crocodiles, the alligators and caimans (family Alligatoridae) and the gharials (family Gavialidae), or even the Crocodylomorpha which includes prehistoric crocodile relatives and ancestors. Crocodiles are large aquatic reptiles that live throughout the Tropics in Africa, Asia, the Americas and Australia. Crocodiles tend to congregate in freshwater habitats like rivers, lakes, wetlands and sometimes in brackish water. Some species, notably the Saltwater Crocodile of Australia, Southeast Asia and the Pacific islands often live along the coastal areas. It is also known to venture far out to sea. They mostly feed on vertebrates like fish, reptiles, and mammals, sometimes with invertebrates like mollusks and crustaceans, depending on species. They are an ancient lineage, and are believed to have changed little since the time of the dinosaurs.

Crocodiles are among the more biologically complex reptiles despite their prehistoric look. Unlike other reptiles they have a four-chambered heart, diaphragm and cerebral cortex. Their external morphology on the other hand is a sign of their aquatic and predatory lifestyle. A crocodile’s physical traits allow it to be a successful predator. They have a streamlined body that enables them to swim faster. They also tuck their feet to their sides while swimming, which makes the animal even faster, by decreasing the water resistance. They have webbed feet which, although not used to propel the animal through the water, allow it to make fast turns and sudden moves in the water or initiate swimming. Webbed feet are an advantage in shallower water where the animals sometimes move around by walking.

Crocodiles are very fast over short distances, even out of water. They have extremely powerful jaws capable of biting down with 3,000 pounds of pressure per square inch, and sharp teeth for tearing flesh, but cannot open their mouth if it is held closed. There are stories of people escaping from the long-snouted Nile Crocodile by holding its jaws shut. Zoologists will often subdue crocodiles for study or transport by taping their jaws or holding their jaws shut with large rubber bands cut from automobile inner tubes. All large crocodiles also have sharp and powerful claws. They have limited lateral movement in their neck, so on land protection can be found by getting even a small tree between the crocodile's jaws and oneself.

There is no reliable way of measuring crocodile age, although several techniques could be 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 apparently aged 115 years old.

West African dwarf crocodile from the forests of West and West Central AfricaA 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.

Size greatly varies between species, from the dwarf crocodile to the enormous saltwater crocodile. Large species can reach over 5 or 6 meters long and weigh well over 1200 kg (2,640 lb.). Despite their large adult size, crocodiles start their life at around 20 cm long. The largest species of crocodile is the Saltwater Crocodile, found in northern Australia and throughout South-east Asia. According to some scientists, there are no truly reliable records of any non-prehistoric crocodiles over 8.64 m.

In the town of Normanton, Queensland, Australia, there is an 8.63 meter fibreglass mould of a crocodile called "Krys the Croc.," shot in 1958 by Krystina Pawloski, who found the animal on a sandbank on the Norman River.

The other two larger certifiable records of complete crocodile are both of 6.2 m 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 this latter 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 (Thai: ใหญ่, meaning big) (born 10 June, 1972) at the famous Samutprakarn Crocodile Farm and Zoo, Thailand. This animal measured 6 m in length and weighs 1,114.27 kg (2,450 lb.).

Another huge captive specimen was a salt water crocodile named Gomek. Gomek was captured by George Craig in Papua New Guinea and sold to St. Augustine Alligator Farm in Florida. Gomek died of heart disease in February 1997. By this stage, he was a very old crocodile. When he died, he was 5.5 m long - as confirmed by St. Augustine Alligator Farm - and probably between 70 and 80 years old.

On June 16, 2006, a 7.1 m giant saltwater crocodile in Orissa, India was crowned the world's largest living crocodile. It lives in Bhitarkanika Wildlife Sanctuary and in June 2006, was entered in the Guinness Book of World Records.

Wildlife experts, however, argue that the largest crocodile so far found in the Bhitarkanika was almost 7.62 m which could be traced from the skull preserved by the Kanika Royal Family. The crocodile, probably was shot dead near Dhamara during 1926 and later its skull was preserved by the then Kanika King. The crocodile experts said the crocodile would be about 7.62 m since the size of the skull was measured one seventh of the total length of the body.

Crocodiles are ambush hunters, waiting for fish or land animals to come close, then rushing out to attack. As cold-blooded predators, they can survive long periods without food, and rarely need to actively go hunting. The crocodile's bite strength is up to 3,000 pounds per square inch, comparing to just 100 psi for a Labrador Retriever, 350 psi for a large shark, or 800 psi for a hyena. Despite their slow appearance, crocodiles are top predators in their environment, and various species have been observed attacking and killing sharks. A famous exception is the Egyptian Plover which is said to enjoy a symbiotic relationship with the crocodile. According to unauthenticated reports, the plover feeds on parasites that infest the crocodile's mouth and the reptile will open its jaws and allow the bird to enter to clean out the mouth.

Crocodiles eat fish, birds, mammals and occasionally smaller crocodiles. Wild crocodiles are protected in many parts of the world, but they also are farmed commercially. Their hide is tanned and used to make leather goods such as shoes and handbags, whilst crocodile meat is also considered a delicacy in many parts of the world. The most commonly farmed species are the Saltwater and Nile crocodiles, while a hybrid of the Saltwater and the rare Siamese Crocodile is also bred in Asian farms. Farming has resulted in an increase in the Saltwater Crocodile population in Australia, as eggs are usually harvested from the wild, so landowners have an incentive to conserve crocodile habitat. Crocodiles are more closely related to birds and dinosaurs than to most animals classified as reptiles, the three being included in the group Archosauria ('ruling reptiles').

A crocodile also played a part in the now legendary video known as the Battle at Kruger.