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Australian Saltwater Crocodile (Estuarine, Indopacific, Rawing, Maneating or Subwater Crocodile)


Image (c) Adam Britton, crocodilian.com

The world's largest living reptile


Order: Crocodylia

Family: Crocodylidae

Subfamily: Crocodylinae

Genus & Species: Crocodylus porosus

APPEARANCE

The Australian saltwater crocodile is one of the most aggressive and dangerous crocodiles. Is is also the largest living reptile, exceeding the Komodo dragon in size. Sexual dimorphism is present in this species, with the females attaining lengths of 10 ft (3 m) and males 10-19.5 ft (3-6 m). 27 ft (10.6 m) specimens have been recorded in the wild, but are extremely rare.

Australian saltwater crocodiles have very large heads. A pair of ridges run from the eyes along the center of the snout. The eyes, ears, and nostrils are located on the same plane on the top of the head, allowing for it to see, hear, and breathe while almost totally submerged. The eyes have a special second pair of eyelids known as the nictitating membrane. These eyelids are clear and protect the eyes while underwater. The ears, situated behind the eyes, have flaps which also close while underwater. The jaws are heavyset and contain 64-68 teeth. The teeth in the upper jaw are perfectly aligned with those in the lower jaw. The fourth tooth on each side of the bottom jaw is larger than the other teeth and is visible when the mouth is closed.

Juvenile Australian saltwater crocodiles are yellow in colour with black stripes and spots. As they mature, the colour becomes paler and the stripes indistinct until they disappear. Adults are dark in colour with light grey areas. The belly is yellowish and the underside of the tail is grey near the tip. Dark bands are located on the lower flanks. The hide lacks osteoderms (bony plates) and is ideal for tanning in the leather industry. Scales are oval in shape and the scutes are small. The colouration of this species differs in regions; some areas have juveniles much lighter in colour than elsewhere.

HABITAT

The Australian saltwater crocodile is a mostly aquatic animal that rarely spends time on land. They are found mainly in brackish waters near rivers or coasts, but can also be found in freshwater rivers. The juveniles are raised in fresh water, the adolescents in more saline water. They move from water to water between the dry and wet seasons. Australian saltwater crocodiles are very territorial. The weaker ones are kicked out of their territories and pushed out into the sea, where they might swim over 1000 km to establish a new territory. Because of this they have a wide range, including Australia, Papua New Guinea, Indonesia, Sri Lanka, Philippines, Singapore, Bangladesh, Japan, Vietnam, Thailand, Solomon Islands, and various other islands in both the Pacific and Indian Oceans. They have been exterminated from the Seychelles islands.

FOOD

Australian saltwater crocodiles will eat almost anything that they can overpower, including humans. Their reputation as a maneater is real, but grossly exaggerated. More people are killed by vending machines than by Australian saltwater crocodiles (that's a fact!)

Juveniles feed on insects, crustaceans, small reptiles, frogs, and small fish. More mature, larger crocs eat turtles, goannas, snakes, birds, livestock (cows), buffalo, monkeys, wild boar, and mudcrabs.

ENEMIES

Australian saltwater crocodiles were once hunted extensively by humans for their hide, which is the most valuable of all the crocodiles. In many countries, such as Australia, hunting is illegal, yet they are still hunted by poachers. Australia has a population of 100 000 Australian saltwater crocodiles and in 1997 aboriginals were given the right to hunt wild adults. This hasn't significantly altered their population. On other islands, however, they have been hunted almost to extinction, due to their hide and their reputation as maneaters. Humans aren't their only threat. On the island of Sri Lanka (Ceylon), feral buffalo destroy their nesting habitats. Monitor lizards and feral and wild pigs eat their eggs, and the juveniles are eaten by goannas, turtles, Australian freshwater crocodiles and territorial Australian saltwater crocodile males. Currently, Australian saltwater crocodiles are labeled as low risk.

BREEDING

Australian saltwater crocodiles reach sexual maturity at 10-12 years and males at 16 years. Mound nests are made between November and March, and 40-60 eggs are laid. If the nest is around 31.6 C, all the eggs will become male. Above or below that and they are females. The eggs hatch after 90 days. Only 1% of the hatchlings will make it to maturity.

RELATIVES

There is one suggested subspecies, C. p. minikanna. There are also hybrids with the Siamese crocodile.

RESOURCES CITED

1. www.flmnh.ufl.edu/natsci/herpetology/brittoncrocs/csp_cpor.htm
2. www.flmnh.ufl.edu/cnhc/%21cpor3.htm
3. mrk.kroc.sandi.net/%2Astudent_projects_97_98/Australiananimals/
Australia9.html
4. www.ozramp.net.au/~senani/crocodile.htm
5. "Estuarine Crocodile" www.?.?

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