Adult crocodiles feed on crustaceans, fish, small mammals, and water birds; the young feed on frogs and small insects. Adults approach a swimming animal from under water and drag it down until it drowns. Crocodiles do not chew their food; if their prey is too large to be swallowed whole, they grasp it with their teeth and twist their bodies in order to tear chunks of flesh from it. According to a medieval fable, the crocodile sheds tears for its victims as it devours them. Thus the expression "crocodile tears" refers to false sympathy.

The female builds a nest of sand, sticks, and vegetation. The mound of material is usually one foot (30 cm) high and 10 feet (3 m) long. She lays 20 to 60 white eggs in the nest and incubates them for three months. After the young hatch, the mother carries them in her mouth to the nearest body of water. The young are eight to nine inches (20 to 23 cm) long at birth. They mature in five years.

In tropical areas, seasons can be rainy or dry. During the dry season, many crocodilians must search for places that still have water.

The Orinoco (ohr uh NOH koh) crocodiles of South America are one example. During the rainy season, their grassland homes are flooded. Rivers flow in places that are dry at other times of the year. There are many places to swim, bask, and feed. But in the dry season, many of these areas dry up. The crocodiles must return to their watery burrows or search for new watery pools.

Orinoco crocodiles are very protective parents. At night, hatchlings may wander off by themselves to look for food. But during the day, their mother stays with them in a group called a pod. She protects them for a good reason. In South America, giant otters prey on young crocodiles. These otters can reach lengths of 7 feet (2 meters).

Crocodilians have many different ways to catch prey. Nile crocodiles of Africa even set traps to catch fish.

A good time to watch trap-setting is when great numbers of fish are found in one area. This happens when fish are searching for food. It also happens when fish swim upstream to spawn, or lay eggs.

Nile crocodiles use their bodies to set traps. They line up next to each other in a stream. As fish swim by, the crocodiles catch them with a snap of their jaws. A single crocodile may also use its body to block a part of a stream. This forces fish to swim around the crocodile and—snap! The crocodile swings its head sideways and grabs the fish.

Crocodiles do seem to share food, but probably not out of kindness. The real reason they share is out of need. Often, crocodiles need other crocodiles to help them eat prey that can’t be swallowed whole.

The Nile crocodile eats fish. But it also preys on large animals such as zebras and wildebeests (WIHL duh beests). Once a crocodile sights its prey, it submerges and swims in close for the attack. Then it grabs the animal, drags it into the water, and drowns it. The noise and splashing of the kill attracts other crocodiles.

Even though one crocodile does the killing, several crocodiles help eat the prey. The crocodiles take turns biting, twisting, turning, and rolling to tear off bite-sized pieces. After a few bites, a crocodile may swim away. Another crocodile takes its place. Larger, more dominant crocodiles usually get most of the food.

Like all crocodilians, the female mugger defends her nest, helps the eggs hatch, and protects the hatchlings. But with mugger pairs, the male helps.

Male muggers are very good fathers. They help the females uncover nests when the hatchlings begin to chirp. Males help hatch eggs by rolling the eggs in their mouths. They also help carry hatchlings to the water. A male mugger may even chase away a female so that he can hatch the nest of eggs on his own.

Mugger crocodiles form family groups. In this way, both parents can care for and protect the young. Mugger parents may protect their hatchlings for up to two years.

Many crocodiles can live in fresh water and in salt water. But Australian saltwater crocodiles spend more time in salt water than any other crocodile. Salties, as they are called, can even swim hundreds of miles to reach new territories. Some spend so much time at sea that they have barnacles, a kind of sea animal, growing on them.

Australian saltwater crocodiles are the largest reptiles in the world. They can reach lengths of 23 feet (7 meters). Still, these giant crocodiles can leap high out of the water. When this happens, it looks as if they are walking on their tails.

Salties are very territorial, and they will attack to defend their territories from other crocodiles. Salties also have attacked and killed humans. This makes the Australian saltwater crocodile one of the most feared crocodilians.

Two kinds of crocodiles live on the continent of Australia. And both hold crocodilian records. The Australian saltwater crocodile is the largest. The Johnston’s crocodile, or Australian freshwater crocodile, is the fastest.

Johnston’s crocodiles are small and shy. They avoid humans and run if they feel threatened. Sometimes a run turns into a bounding gallop. First, the back legs push the animal forward. Then the front legs hold it up while the back legs swing forward for another push. Johnston’s crocodiles can gallop as fast as 10 miles (16 kilometers) an hour.

Johnston’s crocodiles live in freshwater lakes, streams, and swamps. These small crocodiles have long, narrow snouts and very sharp teeth—perfect for catching and eating fish.

Crocodiles belong to the family Crocodylidae. The American crocodile is Crocodylus acutus; the saltwater, C. porosus; the Nile, C. niloticus.