Although sharks, whales, dolphins and seals might be the first animals that spring to mind when thinking of the ocean, marine ecosystems are also home to some reptiles.
Turtles, marine iguanas, and sea snakes have all evolved to live in our seas. But what about crocodiles?
Are there any crocodiles in the sea?
People often think of crocs as only living in rivers and lakes but saltwater crocodile (Crocodylus porosus) – also called estuarine crocodiles or, more affectionately, ‘salties’ – can live in fresh, brackish, and saltwater.
These animals can be found in the Indo-Pacific: from northern Australia through south east Asia and into India. “The species can be found in a wide range of habitats, including rivers, estuaries, creeks, swamps, lagoons and billabongs,” says the Australian Museum on its website. “They can tolerate salinities ranging from 0% (freshwater) to 35% in full strength sea water and have even been recorded in water twice as saline (70%) as sea water.” Although all seas are salty, salt levels vary across regions and the sea is generally much saltier than rivers.
Why can saltwater crocodiles survive in the sea?
These crocodiles can endure salt water thanks to a special gland under their tongue that excretes salt.
How far do saltwater crocodiles swim out to sea?
These prehistoric predators have been spotted miles out at sea. However, they are not strong swimmers so they hitchhike on ocean currents to travel long distances.
How large are saltwater crocodiles?
The largest species of crocodile in the world, male salties can grow up to seven metres, although they tend to be around five metres on average and females are much shorter than males (typically, around three metres). The largest captive crocodile ever recorded was a male saltwater crocodile named Lolong who measured 6.17 metres and weighed 1,075 kg.
What do saltwater crocodiles eat?
Saltwater crocs have a varied diet. “They will eat just about any animal that they can catch and overpower,” says the Australian Museum. Their diet includes everything from insects, fish, crustaceans and birds to turtles, goannas and water buffalo. These known cannibals have even been recorded eating other saltwater crocodiles.
How do saltwater crocodiles hunt?
Saltwater crocodiles have a lay-in-wait hunting strategy, sitting quietly in the water until they identify their target. “When prey is detected, the crocodile makes a stealthy approach under water, keeping any exposure to a minimum,” says the Museum. “Once in range, the crocodile lunges rapidly and slams its jaws shut on the victim – the force of this alone may be enough to kill it.”
The bite of a saltwater crocodile is around twice as strong as that of a great white shark, measuring around 1,700kg. Such immense force is enough to crush small prey but the croc might need to tear bigger animals apart to be able to swallow them.
“If the meal is too big to be swallowed whole, the crocodile will grab hold with its jaws and shake violently or roll to tear off a manageable piece,” the Museum says. This is sometimes known as a ‘death roll’. If its eyes are bigger than its stomach, and there is meat leftover once the croc is full, it caches the remains so it can go back and eat them later.
“The Australian saltwater crocodile is one of the most aggressive and dangerous crocodiles,” according to the Northern Territory Government’s Be Crocwise website.
How can you stay safe from saltwater crocodiles?
There are a few things you can do to stay safe in crocodile habitats: follow all warning signs; supervise children and teach them how to behave safely; use a torch when walking at night; keep your arms and legs inside the vessel when on a boat; don’t camp close to the water; don’t leave animal or fish remains close to areas where people use the water for swimming or other recreational activities; and don’t let dogs or small children wander close to the water’s edge – even very shallow bodies of water can have crocs.
“If camping on a beach, be aware that estuarine crocodiles sometimes come ashore at night,” notes the Australian Museum, adding that this large apex predator “is likely to consider humans as potential prey.”
More of your wildlife questions answered
- Do seabirds drink saltwater?
- What's the smallest crocodile?
- What's the most dangerous animal in Australia? Does the country's wildlife deserve its deadly reputation?
- Can alligators and crocodiles crossbreed?
Main image: saltwater crocodile in the Hunter River on Mitchell Plateau, Western Australia. Credit: Getty
