Last week we introduced you to a species of animal many of you may not have wanted to even learn about because of their appearance and nature of most members of this group. Today too we like to bring you some interesting facts about the largest members that belong to the group of reptiles; the crocodiles and alligators. They are definitely not a species of animal with great looks or reputation.

The very mention of their names may send a shiver down your spine because they are generally noted as man-eaters. You are bound run shrieking the moment you see a crocodile (we do not have alligators in our country). They are indeed scary looking animals but they are powerful creatures that we need to learn about and also protect because today they are being hunted down almost to extinction.. At a glance crocodiles and alligators may look the same but there are many differences between the two species. So, let's see how you can identify them apart. Did you know that the first difference between a crocodile and an alligator is that they belong to two different families of crocodilians? Whilec rocodiles are from the crocodylidae family alligators and caiman are from the alligatoridae family. But this family difference is not going to help us tell them apart. So, we need to look for a physical difference that could be easily spotted and the easiest way to do so is to check the appearance of their snouts. The crocodile has a very long, narrow, V-shaped snout, while the alligator's snout is wider and U-shaped. Because of the wide snout of the alligator it has more crushing power to eat prey like turtles that are a part of its diet. The narrow crocodile snout, although still very powerful, is not really suited for prey like turtles but is very versatile for fish and mammals. But wait.

There is a more interesting way to tell the difference between a crocodile and an alligator. However, you cannot do this from a distance. You need to see it at a closer range to do so. And that is to see how the animal smiles! Well, actually what you need to do is examine (from a safe distance of course) how the mouth or snout of the animal looks like when it is closed. The crocodile's upper and lower jaws are nearly the same width, so the teeth are exposed all along the jaw line in an interlocking pattern, even when the mouth is closed. The crocodile also has an enormous fourth tooth on the lower jaw that is accommodated by depressions in the upper jaw just behind the nostrils. An alligator, on the other hand, has a wider upper jaw, so when its mouth is closed the teeth in the lower jaw fit into sockets of the upper jaw, hidden from view. Only the teeth of the upper jaw are exposed along the lower jaw line. Even the enormous fourth tooth on the bottom jaw, which is exposed in a crocodile, is hidden in the alligator.

Another physical difference you should look for is their colour. Crocodiles have a lighter olive brown colouration, while alligators appear blackish. Alligators also prefer freshwater while crocodiles like brackish water and sometimes even the ocean. The reason the alligators do not like the ocean is because even though they both have glands on their tongues, crocodiles still use these glands to excrete excess salt while alligators seem to have lost this ability, making their tolerance for salt water comparatively brief. Both crocodiles and alligators have dotted sensory pits along the upper and lower jaws that look almost like beard stubble. They detect slight changes in water pressure, thought to help the animals locate prey. These sensory pits were called Integumentary Sense Organs (ISOs) until they were renamed to Dermal Pressure Receptors (DPRs). While both animals have them along the jaws, the crocodile has one on every scale covering its entire body. Some researchers believe the crocodile's DPRs might be linked to detecting levels of salinity.

It is generally stated that alligators are docile compared to aggressive saltwater crocodiles, and that crocodiles grow larger. While true in general, there are exceptions to every rule among the many species. As an example, the average alligator grows to about 14 feet (4.3 meters), while crocodiles can reach 19 feet (5.8 meters) or more. But there is one species of crocodile - the African dwarf - that barely reaches five feet (1.5 meters). Also, the Indian mugger crocodile has a decidedly U-shaped snout, breaking the V-shaped rule.

In terms of nesting, crocodiles lay their eggs in mud or sand nests near brackish water, while alligators make their nests out of mounds of vegetation surrounding freshwater. Crocodilians, which includes both crocodiles and alligators, are believed to have descended from archosauria which lived 250 million years ago at the end of the Paleozoic era when all the continents were joined together in a single mass known as Pangea. About 30 million years later in the Triassic period (220 million years ago) archosauria split into two lines of evolution, one being crocodilians and the other dinosaurs and birds. Scientists theorise that the Age of Reptiles, which lasted some 155 million years, ended about 65 million years ago when an asteroid struck Earth wiping out the dinosaurs. But while dinosaurs vanished crocodilians survived!

There are plenty of crocodiles in our country, so have you ever encountered one of these creatures with a nasty reputation? If you ever do be very careful not to go near it. If the animal is really, really hungry it may decide to make a meal out of you. So watch out and even if it seems as if the crocodile is smiling at you don't be fooled. Remember to never, ever smile at a crocodile when you see one . They are very unpredictable animals and use camouflage too to catch their prey when they are hungry.

Sometimes they resemble a floating log in the water and you would not even think it is a crocodile unless you observe it closely and notice the eyes above the water.

Facts and pix: Internet

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Fast facts

* The saltwater crocodile is believed to be the largest crocodile

* The alligators and their relatives, the caimans are very similar to crcodiles and their cousins, the gharials.

*Crocodiles have pointed looking snouts, alligators have wide flat heads and rounded noses, caimans also have similar features but gharials have long thin snouts that they use for fishing.

*Crocodiles have great teeth. Did you know that they never have to worry about their teeth wearing off because they can always grow another set of teeth? As the animal grows and the teeth wear down it is replaced by another set of sharp new ones growing in its jaws. A Nile crocodile would probably have used up 45 sets of teeth by the time it is a young adult. The Nile crocodile is also famous for brushing or rather cleaning its teeth. It could be seen resting with its mouth wide open while birds eat the parasites in between the teeth.

* There are 23 species of crocodile and they inhabit the Southern reaches of the world. They can be found in the swamps and everglades of the southeastern U.S., in Central and South America, in Africa, Australia, India, Sri Lanka, Pakistan, Malaysia and Borneo.

* American alligators' teeth only show if their mouths are open. American crocodiles, even with their mouths snapped shut, display a tooth on either side of their lower jaw. Other crocodiles can show a bristle of sharp, lower teeth.

*All crocs can be vicious. They are able to attack with lightening speed and kill animals as heavy as they are. The most terrifying are the Nile and Australian crocodiles. Nile crocodiles can take down a water buffalo! They are crafty and can plot their hunting behaviour to match their specific prey.

* Crocodiles have nests of eggs called clutches. Some crocodiles will dig from 10 to 30 feet into a creek bank to create a protected burrow for their nests. They create a hidden entrance to the burrow that is at the water line or just below it. A clutch of eggs can have as few as eight eggs and as many as 80. Crocodile eggs take about 85 days, or almost three months, to incubate. Mother crocodile will sometimes help the babies hatch by gently cracking the eggs.

*There are two species of alligators large type found in the S United States and a small type found in E China. The American alligator, Alligator mississipiensis, is found in swamps and sluggish streams from North Carolina to Florida and along the Gulf Coast. When young, it is dark brown or black with yellow transverse bands. The bands fade as the animal grows, and the adult is black. Males commonly reach a length of 9 ft (2.7 m) and a weight of 250 lbs (110 kg); females are smaller.

* The caiman (scientific name: Caiman crocodiles) is a reptile similar to the crocodile that inhabits the South and Central American continent, favouring the river and wetland areas, being able to live in both fresh and salt water. The males range between six to seven feet in length with the females reaching about five feet.