ANIMAL WORLD

THE FASCINATING WORLD OF CROCODILES

These humongous lizards which can conveniently outgrow 6 metres are found in tropical areas of Asia, Africa and the Americas. Yes, crocodiles are very sensitive to cold. They are polyphyodonts, just like sharks; they are capable of replacing their teeth continuously – all 80 of them. Beside each fully grown tooth is a 'baby tooth' just waiting to step into the gap if the mature tooth falls off. Impressive! And unlike all other reptiles, crocs have a four-chambered heart.

Now, these majestic beasts have acute senses. Their eyes, ears and nostrils are on top of their head, allowing them to go very low in water while still remaining functional, alert and conscious of their surroundings. They are ambush hunters – they remain hidden till a prey comes close, and then, with a sudden burst of speed, they go for the kill. They eat a wide variety of animals including birds, reptiles, mammals and even smaller crocodiles. Younger crocs prefer invertebrates and fishes and gradually change to bigger meals as they grow older. Quite amazingly, sharks and big cats aren't safe from these strong hunters as an adult crocodile will make a meal of them if opportune. They eat carrions, and also weak or dying hippos and elephants.

What is also spectacular is their stomach structure. They have the most acidic stomach of any vertebrate, making them capable of efficiently digesting bones, horns and hooves. They will digest whole animals within a matter of hours.

What about their bite force? Crocodiles can bite down on prey with an amazing force of over 22000N. In fact, there's a record of 34000N! That's 21 times stronger than the bite force of a Rott! Even the great white shark bites at just 18000N. Once a prey is caught, well...

As big and 'slow' as they appear, crocodiles can 'run' at speeds up to 11kmh. That's just about half of how fast an average human runs. Well, at this speed, there's a limit to the animals they can keep up with on land. But who cares? They rule the waters anyway.

Little can be done in accurately measuring their lifespan, but we know they averagely live for up to 35 years. Some have been monitored to live for over 70yrs, and old Kolya, a male croc in a Russian zoo lived for over a century. Mr. Freshie lived for over 120 years in an Australian zoo.

Crocodile’s reproduction is fantastic. They lay eggs which are incredibly hard shelled. Mating takes place in the water, but egg laying occurs on land. Depending on species, crocodiles can lay up to 95 eggs! They lay their eggs at night and this is usually completed within 40 minutes. And guess what? Crocodile sex isn't determined genetically, but by environmental temperature. Wow, right? At a range of 30°C to 31°C, you mostly get females. 31°C - 32°C, sexes are mixed. 32°C - 33°C, the guys predominantly emerge. Well, 'high temperature females' can still be hatched at this temperature in some species. Incubation takes an average of 80 days. Close to hatching, the young start to call to mummy. They possess 'egg-tooth' at the tip of their snout which they use to break out of the shell. Female crocodiles often gently roll the unhatched eggs to assist the babies in getting out.

ASSOCIATIONS WITH HUMAN

Crocodiles are very dangerous to humans, primarily by their ability to strike faster than humans can react. Salt water and Nile crocodiles kill hundreds of humans yearly in parts of southeastern Asia and Africa. However, that doesn't prevent man from cultivating them. Crocodile farming is widely practiced all over the world for their meat, hides, oil and other products with some farms making over $6m annually. Eggs are also eaten as delicacies in parts of Australia and China.

INTERESTING CROCODILE FACTS

• Crocodiles can close their nostrils when they are completely submerged in water.
• Crocodiles cannot stick out their tongues.
• Crocodiles are born at around 20cm but they can grow up to 700cm, and weigh over 900kg.
• Crocodiles have 80 teeth at a time and up to 3,200 teeth within a lifetime.
• Crocodiles have excellent night vision. At very low lights, they can still see vividly.
• Crocodiles have Domed Pressure Receptors, a feature that allows them detect even very small vibrations in water caused by tiny drops. They can also sense a prey's presence in total darkness.
• The jaw muscles of crocodiles are extremely strong and tough, almost as hard as bone.
• Crocs can communicate with different types of vocalization, including the chirp, bellow, threat, distress and hatching calls.
• Crocodile sex is determined by temperature, not chromosomes (I bet you know that already).
• Crocodiles have some advanced cognitive abilities. They can recognize drinking patterns of animals and they can bait birds with sticks used for nesting, especially during the spring. They also make cooperative hunting when a large prey is involved with one holding down the animal while others are tearing it apart.

These fearsome creatures are wonderful in many regards. In water, they are afraid of almost nothing. On land, well, don’t come close. They are fearsome hunters and have a diverse diet. Their excellent streamlined body and webbed feet makes them great swimmers just as their wonderful senses keep them on top of the game. Needless to say, they aren’t animals to be joked with or handled lightly.