The saltwater or estuarine crocodile is the largest of all living reptiles. It is found in suitable habitats in Northern Australia, the eastern coast of India and parts of Southeast Asia. The largest size saltwater crocodiles can reach is the subject of considerable controversy. The longest crocodile ever measured snout-to-tail and verified was the skin of a dead crocodile, which was 6.1 metres long. A crocodile shot in Queensland in 1957 was reported to be 8.5 metres long, but no verified measurements were made and no remains of this crocodile exist. A "replica" of this crocodile has been made as a tourist attraction.
Saltys (as they are often referred to in northern Australia) are very common in the northern parts of Northern Territory, Western Australia and Queensland, particularly in the multiple river systems near Darwin (such as the Adelaide, Mary and Daly Rivers, along with their adjacent billabongs and estuaries) where large (6 metre plus) individuals are common. The Australian Saltwater Crocodile population is estimated at somewhere between 100,000 and 200,000 adults.
Saltwater crocodiles are very dangerous and do cause physical injuries and/or death to humans who enter a crocodile's territory. To avoid crocodiles, stay away from the waters of rivers, estuaries and coastal water pools. Do not enter the water, even if crocodiles are not visible, and stay away from river banks and sand bars.
For me, the safest and best way to see crocodiles at close range but in the wild is on the jumping crocodile cruises that operate near Humpty Doo on the Adelaide River less than an hour's drive south-east of Darwin. On these cruises, vessels take visitors down the river to view wild crocodiles on the Adelaide River and its banks. Selected crocodiles are fed meat on poles, this encourages them to jump out of the water and take the food. These jumps occur close to cruise vessels, and offer amazing photo opprtunities.
Many zoos and wildlife sanctuaries around Australia have saltwater crocodiles in their collections, through most are not in enclosures that resemble their natural habitat. It is possible to view saltwater crocodiles in their natural habitat but also in captivity at numerous crocodile farms in the northern territory and north Queensland. At many of these farms, visitors can not only walk close to crocodiles in enclosure, but also take cruises into billabongs where the animals can be seen in the wild.
In northern Australia (which includes the northernmost parts of the Northern Territory, Western Australia and Queensland) the Saltwater Crocodile is thriving. Their range extends from Broome in Western Australia through the entire Northern Territory coast all the way down to Rockhampton in Queensland. The Alligator Rivers of Northern Australia are misnamed due to the resemblance of the saltwater crocodile to alligators as compared to freshwater crocodiles, which also inhabit the Northern Territory.
Saltwater crocodiles generally spend the tropical wet season in freshwater swamps and rivers, moving downstream to estuaries in the dry season, and sometimes traveling far out to sea. Crocodiles compete fiercely with each other for territory, with dominant males in particular occupying the most eligible stretches of freshwater creeks and streams. Junior crocodiles are thus forced into the more marginal river systems and sometimes into the ocean. This explains the large distribution of the animal (ranging from the east coast of India to northern Australia) as well as its being found in odd places on occasion (such as the Sea of Japan).
Like other sea turtles, they migrate long distances between feeding grounds and hatching beaches. Many islands worldwide are known as Turtle Island due to Green sea turtles nesting on their beaches. Females crawl out on beaches, dig nests and lay eggs during the night. Later, hatchlings emerge and walk into the water. Those that reach maturity may live to age 80 in the wild.
The saltwater crocodile is an opportunistic apex predator capable of taking nearly any animal that enters its territory, either in the water or on dry land. They are known to attack humans who enter the crocodiles' territory. Juveniles are restricted to smaller animals such as insects, amphibians, crustaceans, small reptiles, and fish. The larger the animal grows, the greater the variety of animals it includes in the diet, although relatively small prey make up an important part of the diet even in adults. Large adult saltwater crocodiles can potentially eat any animals within their range, including monkeys, kangaroos, wild boar, dingos, goannas, birds, domestic livestock, pets, humans, water buffalo, gaurs, bats, and even sharks.
Domestic cattle, horses, water buffalo, and gaur, all of which may weigh over a ton, are considered the largest prey taken by male crocodiles. Generally very 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, preferring to hunt at night. Saltwater crocodiles are capable of explosive bursts of speed when launching an attack from the water. Stories of crocodiles being faster than a race horse for short distances across the ground are little more than urban legend. At the water's edge, however, where they can combine propulsion from both feet and tail, eyewitness accounts are rare.
It usually waits for its prey to get close to the water's edge before striking, using its great strength to drag the animal back into the water. Most prey animals are killed by the great jaw pressure of the crocodile, although some animals may be incidentally drowned. It is a powerful animal, having the strength to drag a fully grown water buffalo into a river, or crush a full-grown bovid's skull between its jaws. Its typical hunting technique is known as the "death roll": it grabs onto the animal and rolls powerfully. This throws any struggling large animal off balance, making it easier to drag it into the water. The "death roll" is also used for tearing apart large animals once they are dead.
Baby saltwater crocodiles may fall prey to monitor lizards, predatory fish, birds, and many other predators. Juveniles may also fall prey to Bengal tigers and leopards in certain parts of their range, although this is rare.