Saltwater crocodile ~ a stealthy, deadly and lurking predator

The saltwater crocodile, estuarine crocodile (Crocodylus porosus) or “saltie” as they are most commonly called in Australia are the largest living crocodilian species in the world. Their history dates back over 240 million years to the reptilian era, and are one of the oldest animals on the planet.

Saltwater crocodile, Kakadu National Park, Northern Territory
Saltwater crocodile, Kakadu National Park

They are one of the biggest and fiercest predators in the world reaching up to 6 metres in length, and weighing in at around 1000kg. Their lifespan is around 70 years.

With 66 – 68 teeth some of which are up to 13 cm long, and with the strongest bite-pressure of all animals, this makes them a deadly ace predator. If they lose a tooth, there is always a new one that grows in its place. Their jaws are wavy and both upper and lower teeth can be seen eternally.

Known as highly stealthy hunters, due to their patience, ability to hold their breath for an hour underwater, and transparent eyelids allowing them to see when fully submerged. Their forward-facing eyes allows them to see and gauge distances for all unsuspecting prey. 

Teethy grinning saltwater crocodile
Teethy grin

Their incredibly strong tails enable them to launch out of the water or other hiding places to catch their prey. Coupled with their very strong legs they are able to move very fast before their unsuspecting prey have time to flee.

Being cold-blooded, salties are unable to generate their own heat, therefore tropical habitats are ideal for these reptiles. They are also not able to sweat, so they will often be seen on riverbanks, cooling off with their mouths open.

Saltwater crocodile, estuarine crocodile
Saltwater crocodile warming up on the bank of a billabong, Mt Borradaile, NT Australia

Being ‘ace predators’ they see anything as suitable prey, including humans. Their main diet consists of smaller reptiles, fish, turtles, birds, snakes, wild pigs and have been known to eat water buffalo and livestock.

While they may catch their prey underwater, they are only able to eat and swallow above water. Their powerful jaws will clamp down on their prey, crushing it and will then swallow it whole as they are unable to chew or break it into small pieces.

Due to their slow metabolism they can survive for months without food. Salties are often seen lurking along the waters edge, waiting for an opportunity to strike in their usual violent lunge at any unsuspecting prey that approaches them.

Salties can swim at speeds of 32 km/h in water and run on land at speeds of 16 km/h.

They always sleep with one eye open, to keep an “eye” on their surroundings. This is called unihemispheric sleeping where they shut down one side of their brain while keeping the other half on alert.

Saltie attempting camouflage on the billabong banks with one eye open, Mt Borradaile, NT Australia
Saltie attempting camouflage on the billabong banks with one eye open, Mt Borradaile, NT Australia
habitat

Swamps, billabongs, rivers, estuaries across northern Australia, and other parts of Asia (see map). It is estimated that there are around 200,000 salties in Australia. They are mostly found around Darwin and the Mary River, Western Australia and Far North Queensland. They are also found in some islands off the Northern Territory and Queensland coast. They get their name from their ability to survive in both high and low salt, and fresh water.

Map: Queensland Historical Atlas
breeding

Salties lay eggs during the wet season (late October – May/June). Females traditionally lay up to 60 eggs at one time in nests made from vegetation and soil along riverbanks. Their nests are large mounds where they will dig out the centre and lay the eggs inside and cover up with more vegetation. Incubation heat is generated from the rotting vegetation and the sun. The incubation period is around 100 days. Interestingly, it is the temperature of the nests during incubation, that will determine the sex of the young. Lower temperatures produce females and higher temperatures will produce males.

A young 12 week old saltwater crocodile
A young 12 week old saltwater crocodile

Females will stay very near to guard their nests. Upon the eggs hatching the young will chirp to attract the female, who will then dig them out and take them to the water in her mouth. She will continue to protect them until they are able to survive for themselves. At birth the hatchlings weigh around 60g and are approximately 18-25cm long. Sadly, only 1% of hatchlings will survive into adulthood. The eggs and hatchlings are subject to being eaten by goannas, birds, snakes and other salties.

Saltie on the prowl just below the surface
Saltie on the prowl
conservation status

Saltwater crocodiles have very few predators apart from humans, who have traditionally hunted them for their meat, eggs and skins. This almost resulted in their extinction, with only around 300 individuals left in the wild.

Due to this, in 1970 conservation efforts were implemented which deemed crocodiles a protected species and they were placed on the ‘protected species list’, with all crocodile hunting being banned.

Large saltie on alert

Over time the numbers of saltwater crocodiles have significantly increased, and they now form an important part of the ecosystem in the Northern Territory.

Eggs are often predated on by goannas and feral pigs when not guarded by a female.   Young hatchlings are preyed upon by birds of prey, large fish, freshwater turtles and other crocodiles. A number of adult salties are accidentally killed by fishing nets. Parasitic diseases are also affecting their survival.

There are registered commercial crocodile farms in Australia which are the only people allowed to farm and raise crocodiles for the commercial crocodile skin and meat industry, local and international. The are subject to state laws and regulation. Crocodile farming is a mix of wild harvesting and captive breeding (conducted under strict licensing). All trade in crocodile is subject to the Convention on International Trade in Endangered Species (CITES).

danger for humans

Since the 1970’s when crocodile hunting was banned, and with their increasing numbers their habitats have expanded significantly and more crocodiles are encountering people. Despite the many warning signs of the crocodile infected areas many people ignore them, and will venture into crocodile territory and risk being attacked or killed. It is important for people to observe all warning signs and don’t take risks.

Short video below with good advice on being “croc wise”.

https://environment.des.qld.gov.au/wildlife/animals/living-with/crocodiles/croc-wise#video-1

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