Saltwater crocodile ~ a stealthy, deadly and lurking predator

saltwater crocodile

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. They are one of the oldest animals on the planet.

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

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 approximately 70 years.

With 66 – 68 teeth, some of which are up to 13 cm long, they have the strongest bite pressure of all animals. This makes them a deadly ace predator. In addition, if they lose a tooth, there is always a new one that grows in its place. As a result, their jaws are wavy, and both upper and lower teeth can be seen eternally.

They are known as highly stealthy hunters due to their patience and ability to hold their breath for an hour underwater. Additionally, they have transparent eyelids allowing them to see when fully submerged. Finally, their forward-facing eyes will enable them to see and gauge distances for unsuspecting prey. 

Teethy grinning saltwater crocodile
Toothy grin

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

Being cold-blooded, salties cannot 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
Ace Predators

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

While they may catch their prey underwater, they can only eat and swallow above water. Their powerful jaws will clamp down on their prey, crushing it. They will then swallow it whole as they cannot chew or break it into small pieces.

Due to their slow metabolism, they can survive for months without food. As a result, salties are often seen lurking along the water’s 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. Saltwater crocodiles are also found in some islands off the Northern Territory and Queensland coast. They get their name from their ability to survive in high and low salt and freshwater.

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 dig out the centre, 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, the temperature of the nests during incubation 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. She will then dig them out and take them to the water in her mouth. She will continue to protect them until they can survive for themselves. The hatchlings weigh around 60g and are approximately 18-25cm long at birth. 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’. This led to all crocodile hunting being banned.

Large saltie on alert
Crocodile Numbers

Over time the number of saltwater crocodiles has significantly increased. They now form an essential part of the ecosystem in the Northern Territory.

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

Registered commercial crocodile farms in Australia are the only people allowed to farm and raise crocodiles for the commercial crocodile skin and meat industry, local and international. They are subject to state laws and regulations. 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 1970s, when crocodile hunting was banned, and with their increasing numbers, their habitats have expanded significantly. Consequently, more crocodiles are encountering people. Unfortunately, despite the many warning signs of crocodile-infested areas, many people ignore them, venturing into crocodile territory and risk being attacked or killed. Therefore, people need to observe all warning signs and not 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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