Saltwater crocodile Australia
The Saltwater Crocodile found in Australia’s Northern Territory is the world’s largest reptile and has been a formidable predator for over 100 million years.There are two types of crocodiles that can be found in Australia: saltwater crocodile (Crocodylus porosus) and smaller freshwater crocodile (Crocodylus johnstoni).
The Top End waterways are one of the best areas for marine crocodiles to inhabit. It is currently estimated that there are over 100,000 sea crocodiles in NT.
Saltwater crocodiles
Physical features of the crocodile
The Australian saltwater crocodile has a hazardous nature and behaves aggressively. Among all the living reptiles, this kind of crocodile is the largest. Sexual dimorphism (difference) is present in this species: females reach more than 3 metres, and males, as a rule, up to 6 meters. Crocodiles up to 10 metres can be seen very rarely in the wild.
Sea crocodiles have giant heads. A pair of ridges run from the eyes in the center of the muzzle. The eyes, ears and nostrils are on the same plane at the top of the head. It allows them to see, hear and breathe while the rest of the body is almost underwater. The eyes have a second pair of unique eyelids called nictitating membranes. They are transparent and protect the eyes underwater. The ears behind the eyes have flaps that also close underwater. There are from 64 to 68 teeth in their jaws. The alignment of teeth in the upper jaw matches perfectly with those in the lower jaw. The fourth tooth on each side of the lower jaw is larger than the others and can be seen when the mouth is closed.
Habitat and distribution of the saltwater crocodile
As was said before, sea crocodiles live in coastal rivers and wetlands, in the open sea, and on island coasts. They actually spend little time on land. They also penetrate far inland through large rivers and floodplain billabongs to freshwater rivers, streams, and swamps.
These crocodiles can be seen in the Asia-Pacific region, in particular in Australia, Papua New Guinea, Indonesia, Timor-Leste, Malaysia, Myanmar, Sri Lanka, the Philippines, Singapore, India, Bangladesh, Vietnam, Thailand, the Solomon Islands and other islands of the Pacific and Indian Oceans. In the Seychelles, their population has disappeared.
In Australia, sea crocodiles are numerous in freshwater wetlands, floodplains, and tidal parts of some rivers overgrown with mangroves. Sea crocodiles can be found in any salt or freshwater within their range. It is known that sizeable male sea crocodiles defend their Territory, and females defend their nests from predators.
Distribution of marine crocodiles in the Northern Territory
There are two types of (true) crocodiles: the marine (or estuarine) crocodile and the Australian endemic freshwater crocodile. Marine crocodiles live in intertidal and freshwater areas. Marine crocodiles occur naturally at great distances upstream from areas where freshwater crocodiles dominate and are considered typical. Freshwater crocodiles can rarely be seen in intertidal and saline areas. In the Northern Territory, freshwater crocodiles were protected in 1963, and marine crocodiles were protected in 1971.
Join us for a heart-pounding adventure on our jumping crocodile tours from Darwin. Witness these incredible reptiles in their natural habitat.
Do sea crocodiles reproduce?
Female sea crocodiles typically reach sexual maturity between 10-12 years, while males reach maturity around 16. Females build mound-shaped nests in vegetation between November and May, laying an average of 50 eggs. If the temperature in the nest is around 31.6°C, males hatch from all the eggs. Crocodile eggs hatch after 75 days at temperatures above 33°C or below 31°C. Only 1% of hatched crocodiles are estimated to survive to adulthood in the wild.
What is a significant threat to the sea crocodiles?
Once, sea crocodiles were extensively hunted in Australia for their skins. They are internationally regarded as the finest crocodile species worldwide. In many countries, including Australia, crocodile hunting is now illegal, but poaching continues around the world. In some parts of the world, crocodiles have been hunted to near extinction due to the value of their skins, the destruction of their habitat and their reputation as meat eaters.
Humans are not the only threat to crocodiles. Wild buffaloes destroy nesting sites, and goannas can dig eggs out of nests. Barramundi, turtles, freshwater crocodiles and old saltwater crocodiles can eat newborns or young crocodiles.
Other threats to the long-term survival of crocodiles include habitat modification, human population encroachment, encroachment on climate stability caused by changes in sea level rise, and habitat alteration.
What do sea crocodiles eat?
The size of a sea crocodile’s prey is limited only by the size and strength of the crocodile itself. The main sea crocodiles’ food is fish. Nevertheless, they also eat animals such as turtles, goats, snakes, birds, cattle, buffalo, wild boars, and mud crabs. Insects, crustaceans, small reptiles, frogs and small fish are for the younger ones.
Other common crocodile names
Do crocodiles grow fast?
Sea crocodile eggs have various sizes. The average saltwater crocodile egg weighs 113 grams, and the average cub weighs 72 grams with a total length of 29.3 cm; the head is 4.3 cm long, and the length from snout to cloaca is 13.8 cm.
Females usually reach maturity at a length of about 2.3 metres. Males reach maturity at a length of about 3.3 metres. Farmed crocodiles grow faster and reach maturity earlier than wild crocodiles.
FAQ
What is the difference between saltwater and freshwater crocodiles in Australia?
Saltwater crocodiles (Crocodylus porosus) are much larger and more aggressive than Australia’s freshwater crocodiles (Crocodylus johnstoni). “Salties” can grow over 6 metres and inhabit coastal rivers, estuaries, and even the open sea, whereas freshwater crocodiles are smaller (typically under 3 metres) and live in inland rivers and billabongs. The two species rarely overlap, as freshwater crocs avoid saline waters where salties dominate.
Where are saltwater crocodiles found in the Northern Territory?
In the NT, saltwater crocodiles thrive in tidal rivers, mangrove-lined estuaries, floodplains, and billabongs. They’re most common in the Top End, including the Adelaide, Mary, and Daly River systems. Large males defend prime territories, while females protect nesting sites. They can also be found far upstream in freshwater habitats.
How do saltwater crocodiles reproduce?
Females reach maturity at around 10–12 years and build mound-shaped nests in vegetation between November and May. They lay about 50 eggs, and the nest temperature determines the sex of the hatchlings—around 31.6 °C produces all males. Incubation lasts about 75 days, but only about 1% of hatchlings survive to adulthood in the wild due to predation and environmental challenges.
What do saltwater crocodiles eat?
Their diet varies with age and size. Juveniles feed on insects, small fish, frogs, and crustaceans. Adults eat fish, turtles, birds, snakes, cattle, buffalo, wild pigs, and even other crocodiles. They are opportunistic predators, capable of taking prey almost as large as themselves, and are well-adapted for ambush hunting.
What are the biggest threats to saltwater crocodiles?
Historically, overhunting for their valuable skins severely reduced populations until legal protections were introduced in 1971. Today, threats include illegal poaching, habitat loss from development, nest destruction by feral animals like water buffalo, predation on young by goannas and large fish, and climate impacts such as sea-level rise and extreme weather events.
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