Ancient Wonders

croc-lurking

Crocodiles are older than many species of dinosaur

Have you wondered who would win in a fight between a crocodile and a shark. Don’t kid yourself: this thought has crossed your mind before, right? My money is on the croc. Crocodiles, belonging to the family Crocodylidae have been around since the time of the dinosaurs, they survived the dinosaurs actually – their ancestors date back to 200 million years, and have changed very little since. They say that the shark is the perfect predator but the crocodile is the perfect survivor – they are definitely built to last.

Crocodiles average 4.5 metres in length, although saltwater crocodiles can reach 6 metres (last year the world record was set for the longest crocodile measuring 6.7 metres) and weigh up to 1,000 kilograms. Their skin is leathery and tough, but a lot of their weight is put into their powerful tail muscles, which they use to swim— reaching up to 40 km/h in the water—and to launch themselves out of the water and onto unsuspecting prey.

Crocodiles have perfected the ambush attack as their mode of predation. Their eyes and nostrils are located on the top of their head which means they can conceal their 1,000-kilogram bulk beneath the water with the only sign of them being eyes and nostrils above the surface. They can stay like this for hours waiting for prey to come close enough to the water’s edge. They’re opportunistic, meaning they’ll eat pretty much anything: fish, turtles, wildebeests and even baby hippopotamuses. Once their intended prey is within reach they launch themselves suddenly from the water, clamp onto their prey using their jaws, which have the most powerful bite force of any living animal, and start turning over and over in the water in what is called a death roll. The death roll causes the prey to drown. The crocodile then rips large chunks of flesh off the carcass, swallowing pieces whole.

Stones are often found in the stomach of crocodiles, and scientists believe these help grind down meat in the stomach.

The mother factor

While crocodiles might seem rather brutal, they are very tender parents and show some of the highest level of care. Males blow water through their nostrils as a mating display for females (which is apparently quite inviting). Females lay eggs on land in a nest that they build and guard closely during the three-month incubation period. She can lay anywhere between 40 to 60 eggs and, like some other reptiles, the sex of the eggs is determined by temperature within the nest; below 30 degrees Celsius generates females, and above 32 degrees produces males. When the eggs hatch, the hatchlings call out to their mother who uncovers them from the nest and gently carries them to the water in her mouth. Baby crocodiles stay under their mother’s protection for up to two years.

Healing Houdini

Crocodiles also seem to have amazing healing powers. Male crocodiles are fiercely territorial and prone to fighting other males for their territory. It was noticed that despite crocodiles coming away from a fight with scratches and bruises, and sometimes missing limbs, they healed quickly and without infection. In 2005 Dr Adam Britton and Dr Mark Merchant collected and tested crocodile blood against a number of infections, such as Staphylococcus aureus (golden staph), West Nile virus and HIV—it defeated all of the infections. Crocodiles and other crocodilians have an excellent and aggressive immune system, which seems to far outstrip our own. They are now working on synthesising the particular protein, named crocodillin from the blood so that they can develop a drug for human use.

Crocodiles have been around for millions of years and now the only real threat to their survival is humans. Crocodiles are prized for their skin, which makes luxury leather goods, their environments are being destroyed and they are often hunted because they are seen as a threat. Conservation is vital, as it would be a tragedy for the only living dinosaur to die out.

Emma Bastian is a marine biologist based in London and a regular contributor to Science Illustrated.

 

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