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. They feed mostly on vertebrates like fish reptiles and mammals, sometimes on 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. They are believed to be 200 million years old whereas dinosaurs became extinct 65 million years ago; crocodiles survived great extinction events.

Description
Crocodiles like dinosaurs have the abdominal ribs modified into gastralia.Crocodiles are among the more biologically complex reptiles despite their prehistoric look. Unlike other reptiles they incorporate muscles used for aquatic locomotion into respiration (e.g. M. diaphragmaticus giving them the functional equivalent of a diaphragm) cerebral cortex and four-chambered heart. 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 swiftly. Crocodiles also tuck their feet to their sides while swimming, which makes them faster by decreasing 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 have a palatal flap a rigid tissue at the back of the mouth that blocks the entry of water. The palate has a special path from the nostril to the glottis that bypasses the mouth. The nostrils are closed during submergence. Like other archosaurs, crocodilians are diapsid, although their post-temporal fenestrae are reduced. The walls of the braincase are bony but they lack supratemporal and postfrontal bones. Crocodilian scales have pores that are believed to be sensory analogous to the lateral line in fishes. They are particularly seen on their upper and lower jaws. Another possibility is that they are secretory, as they produce an oily substance that appears to flush mud off. Crocodiles are very fast over short distances even out of water. Since crocodiles feed by grabbing and holding onto their prey, they have evolved sharp teeth for tearing and holding onto flesh, and powerful muscles that close the jaws and hold them shut. These jaws can bite down with immense force, by far the strongest bite of any animal. The crocodile's bite force is more than 5,000 pounds per square inch (340 atm) compared to just 335 pounds per square inch (22.8 atm) for a rottweiler, 400 pounds per square inch (27 atm) for a large great white shark, or 800 pounds per square inch (54 atm) to 1,000 pounds per square inch (68 atm) for a hyena. The jaws are opened however by a very weak set of muscles. Crocodiles can thus be subdued for study or transport by taping their jaws or holding their jaws shut with large rubber bands cut from automobile inner tubes. All crocodiles have sharp and powerful claws. They have limited lateral (side-to-side) movement in their neck.

Size

Large Saltwater Crocodile in captivity in AustraliaSize 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.The largest recorded crocodile is a giant saltwater crocodile measured at 8.6 metres (28 ft) and 1,352 kilograms (2,980 lb) shot in Australia, Queensland in 1957. A "replica" of this crocodile has been made as a tourist attraction. The largest living crocodile known is a 7.1 metres (23 ft) long saltwater crocodile, in Orissa, India. It lives in Bhitarkanika Wildlife Sanctuary and in June 2006, was entered in the Guinness Book of World Records. 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.Sweetheart, a large saltwater crocodile that attacked boats
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 measures 6 metres (20 ft) in length and weighs 1,114.27 kilograms (2,456.5 lb).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.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, USA. Gomek died of heart disease in February 1997. When he died he was 5.5 metres (18 ft) long—as confirmed by St. Augustine Alligator Farm and probably between 70 and 80 years old.Yet another enormous crocodile, named Gustave by the Africans who have seen him, is responsible for over 300 human deaths, and allegedly ate an entire adult hippopotamus. He also stars in a film titled Primeval. The crocodile's length is said to be anywhere between 20 feet (6.1 m) to 30 feet (9.1 m) long. He lives along the Ruzizi River in Africa.Wildlife experts, however, argue that the largest crocodile so far found in the Bhitarkanika was almost 25 feet (7.6 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 at about 7.62 metres (25.0 ft) long, as the size of the skull was measured one seventh 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.

GALLERY