Crocodiles
Nile crocodiles at a crocodile farm in Zambia
Image: Hamsterkiste
1 Crocodiles and their relatives
Nile crocodiles at a crocodile farm in Zambia
Image: Hamsterkiste
Crocodiles live in the warm tropical and subtropical regions of the world. They are found in Africa, Asia, Australia, North America and South America. There are about 25 different species of crocodile. The best known include Nile crocodiles, which are found in Africa. Their name comes from the River Nile. Saltwater crocodiles, also known as estuarine crocodiles, live in Australia and Southeast Asia. American crocodiles are found in Central and South America, and dwarf crocodiles in West Africa.
Alligators are closely related to crocodiles. They are found only in the United States and China. Alligators and crocodiles differ in the shape of their heads. Crocodiles are also related to gharials, of which only one species remains: the gharial of India’s Ganges River.
Crocodiles need a warm climate and warm water. They live in rivers, lakes, swamps and mangrove forests. Some species can also live in brackish water, a mixture of fresh and salt water. Crocodiles are good swimmers, but they also spend time on land to regulate their body temperature in the sun.
Find out:
- Where are crocodiles found?
- Which reptiles are crocodiles closely related to?
- Where do crocodiles live?
2 The Crocodile’s Body
One of the largest saltwater crocodiles at the Madras Crocodile Bank, Tamil Nadu (India)
Image: Harikrishnan S - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=117663583
Crocodiles have a tail and four legs that grow out from the sides of their bodies. They vary greatly in size: dwarf crocodiles grow to about 1.5 to 2 metres long and weigh 20 to 80 kg. Nile crocodiles can reach lengths of up to 6 metres, with large animals weighing more than 700 kg. The saltwater crocodile is the largest species. It can grow up to 7 metres long and weigh over 1,000 kg.
Crocodiles have about 60 to 70 sharp teeth. They use them to hold on to and tear apart their prey. They cannot chew with them. If a tooth falls out, a new one grows in its place, throughout their lives. They can move only their upper jaw. Crocodiles have a hard scaly armor that covers their entire body, tail, and legs.
Crocodiles often stay in the shallow waters along riverbanks, where they lie in wait for prey. On land, they usually move very slowly. But for short periods, they can run about as fast as a person. In the water, they can reach speeds of around 30 km/h.
Find out:
4. How long and how heavy can saltwater crocodiles get?
5. How many teeth do crocodiles have?
6. What happens when a tooth falls out?
7. How fast can crocodiles swim?
3 Nutrition and reproduction
A saltwater crocodile on a riverbank near Karamjal, Bangladesh
Image: Fabian Roudra Baroi - Own work, CC BY-SA 4.0,
Crocodiles are predators that feed on the meat of other animals. They catch fish, birds, and small and large mammals. They often lie in wait for their prey in the water and grab it in a flash with their powerful jaws. They also attack large animals such as antelopes, zebras and even buffalo. Crocodiles can stay underwater for up to an hour.
Like all reptiles, they reproduce by laying eggs. A female crocodile lays 20 to 70 eggs in a nest. The eggs lie about 20 cm below the surface. The warmth of the ground incubates the eggs. After about 2 to 3 months, the young hatch. The female often guards the nest and helps the young hatch. The young are about 20 to 30 cm long at birth. They then grow about 30 cm each year.
Crocodiles are sometimes raised on farms, where they often live in cramped conditions. When they are fully grown, they are killed. Their skins are made into crocodile leather, which is considered very durable and valuable.
Find out:
8. What do crocodiles eat?
9. How do crocodiles reproduce?
10. Why are crocodiles sometimes kept on farms?