Sandakan (The Little HongKong)

October 6, 2010

Estuarine Crocodile

Filed under: "SANDAKAN" aka The Little Hong Kong — Cedric @ 1:01 am

The estuarine crocodile is the largest reptile.

There are about 14 species of crocodiles worldwide, of which the estuarine crocodile (crocodylus porosus) is the largest. Also known as the saltwater crocodile, it is found in freshwater swamps, rivers, inter-tidal zones and estuaries throughout Southeast Asia and northern Australasia.

A healthy adult male saltwater crocodile is typically 4.8m – 5 m (15.8ft – 16.6 ft) long, weigh around 770kg (1697 lb). However, this species is capable of growing to sizes up to 9 m (30 feet)!

It’s a very powerful predator!

The estuarine crocodile is an ambush predator capable killing large animals like water buffaloes, although relatively small prey still make up the majority of the diet of adult. In Sabah, it can take monkeys, wild boar, birds, domestic livestock, pets, water buffalo and also humans. Younger crocodiles eat smaller animals like insects, amphibians, crustaceans, small reptiles and fish.

Generally it seems 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, usually preferring to hunt at night.

Estuarine crocodiles can digest mostly everything from their prey, including bones, feathers and horns!

It does not have sex chromosomes.

Crocodile embryos do not have sex chromosomes. This means that the gender or sex of a crocodile is not determined genetically.

Instead, sex is determined by temperature, with males produced at 31.6 C. and females produced at slightly lower and higher temperatures. The average incubation period is around 80 days.

Saltwater crocodiles nest in mounds, raising their eggs above the ground water table. However, many nests are lost to flooding each year. When the eggs are submerged, oxygen cannot reach the embryos and they die within a few hours.

On average, at least 80% of all eggs die during incubation, and less than one percent of all hatchlings will reach maturity. Major predators of the hatchlings include birds and fish, but major cause of death is cannibalism by other adult crocodiles.

Crocodiles have new teeth all the time!

All Crocodilians have replacement teeth all their life (though not in ‘extreme’ old-age). Each tooth is hollow, and the new one is growing inside the old. In this way, a new tooth is ready once the old is lost.

Juvenie crocodile replace teeth with larger ones at a rate as high as 1 new tooth per socket every month. After reaching adult size in a few years, however, tooth replacement rates can slow to two years and even longer. Very old crocodiles may reach an almost toothless state, after teeth have been broken and replacement slowed or stopped.

The result of this is that a single crocodile can go through at least 3,000 teeth in its lifetime!

There are lesser in numbers now.

Estuarine crocodiles are severely depleted in numbers throughout the vast majority of their range. Sightings in Thailand, Cambodia, Laos and Vietnam are becoming extremely rare and the species may even be extinct in one or more of these countries.

However, the species 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 in rare in most areas but is very common in the north eastern part of the country (mainly Orissa and the Sunderbans).

The population is scattered in Indonesia and Malaysia with some areas harbouring large populations (lower Kinabatangan Wildlife Santuary, for example). The estuarine crocodile is also present in very limited portions of the South Pacific, with an average population in the Solomon islands, a very small & soon-to-be-extinct population in Vanuatu Is. (official population = 3) and a decent but at-risk population in Palau Is. (possible rebounding).


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