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The Clickable Croc

Labeled crocodile photo


Those teeth look pretty impressive. But the croc doesn't use its teeth the way you do. The croc's pearly whites are designed to seize and hold prey, not to chew. Crocodiles will swallow their food whole if it's small enough but will use their powerful teeth and jaws to crush and break up larger prey or to splinter the hard outer shell of a crab or a turtle.

Nile crocodiles like this one will eat buffaloes and occasionally people, although humans are not their natural prey. They also scavenge meals, stealing other crocodiles' and other species' kills, and cooperate in hunting, sharing in the kill. They are opportunistic hunters; no meal is too small if it doesn't take too much energy to catch, though they also have adapted specialized behaviors to deal with specific prey.


While the croc's front feet bear sharp claws used for traction and catching prey, its hind feet are webbed. This allows for improved balance and maneuverability when they are stationary or moving very slowly through the water. At higher swimming speeds, they fold their legs straight back and simply use their powerful tail.


The tail provides the main thrust for the crocodile while it swims. Watch a croc swim and you'll see that it seems to make an S shape as it glides through the water. This makes the most efficient use of its body shape and allows it to be a fierce predator. Generally, crocodiles wait until their prey gets close enough to be taken with a lightning-fast movement.


Notice how the nostrils are located on top of the snout. This feature allows the crocodile to breathe while its body is almost completely submerged. When they are above water, crocodiles rely on their sense of smell to locate dead animals. Crocodiles prefer calm water, as a rough surface makes it difficult to keep their snouts above water while swimming.


Check out the neck, body, and tail. There's a thick layer with interlocking scales (called scutes) and bony buttons or plates (called osteoderms) that create an armor for protection. The coloration in the crocodile's skin allows it to blend into its environment, providing camouflage from other creatures.

A croc's skin also plays an important role in the animal's temperature regulation. Crocodiles are heterothermic, meaning that they rely on the interaction of their skin with the environment to maintain proper body temperature. For example, they bask in the sun on land in the morning, then spend the afternoon in the water, exposing only their backs to the sun. Body temperature drops slowly during the night, which they spend in the water, and then the cycle begins all over again the next day. To avoid overheating, crocodiles will cover themselves with mud.


If you could go down the croc's throat and see inside its stomach, you would see two chambers. One chamber grinds up its food, while another contains a digestive system that removes nutrients from the food. The crocodile also has the most acidic digestive system of any animal; it can digest bones, hooves, and horns.


These animals have good vision (they may even see colors) and use sight to catch prey above water. But below the water their eyesight is far from perfect. They can't focus as well, and a third, protective eyelid, called the nictitating membrane, is not completely transparent, so when submerged, crocodiles must also use other senses, including the ability to detect pressure changes around the jaw.



Don't make too much noise—crocodiles have good hearing as well. Their inner ear is well developed, and a movable flap to prevent water from coming in covers their external ear.


They may not speak words, but crocodiles do vocalize. Adults bellow in courtship and hiss and snarl at unwanted guests. Babies make chirping sounds as calls for help.

Outlasting the Dinosaurs | Who's Who of Crocodilians
Wrestling with Crocs | The Clickable Croc | Teacher's Guide | Resources | Transcript

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© | Updated December 2003
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