|Length: up to 20 feet (6 m)
|Up to 2000 pounds (900 kg)
|Fish, turtles, large and small mammals
|25 to 60 eggs
|Adult crocodiles prey on young crocodiles
|No special status
|45 to 80 years
· The scientific name means “crocodile” (Crocodylus) “of the Nile River” (niloticus).
· Crocodiles have narrower snouts than alligators, as well as a tooth protruding from the lower jaw rather than fitting in to the upper jaw.
· Only the hind feet of a Nile crocodile are webbed.
Nile crocodiles have a huge, strong tail that propels them through the water. Their ears are external but they are able to close them, as well as close their nostrils, when going underwater. A thin membrane works as a third eyelid, allowing crocodiles to see underwater but protecting their eyes. Although crocodiles have very strong jaws and can clamp down with tons of pressure on a victim, the muscles that open the crocodile’s jaws are relatively weak—they can easily be held shut.
Nile crocodiles are found throughout most of Africa, including the island of Madagascar, with the exception of the northwest countries of Morocco, Algeria, Tunisia and Libya. Nile crocodiles are the most widespread crocodiles and make their homes in rivers, marshes, lakes and ponds.
Nile crocodiles eat small amounts of food at various intervals throughout the day. They actually eat very little in comparison to their size, and spend much of the day either resting or swimming. Most have about 10 pounds of stones in their stomachs—they swallow them to aid digestion and to add weight, enabling them to stay under the water. They eat mostly fish and turtles, but will also attack and eat baboons, hyenas, buffalo, lions and humans. They sometimes work in groups to bring down prey or to corral fish. To capture large prey, crocodiles wait for it to approach for a drink at the water’s edge. Crocodiles lie just beneath the surface of the water with only their eyes showing. When the prey is close enough, crocodiles rush out of the water and either grab the victim with their teeth or knock it over into the water with their tail, where the crocodiles can move more easily.
Two months after mating, females dig a nest hole on land high enough to prevent flooding. They lay 25 to 60 eggs (similar in size and shape to chicken eggs) in the hole and then cover the nest with vegetation that will rot, creating enough heat to keep them warm. They make frequent trips to their nest to make sure the eggs have not been tampered with. In approximately three months, the eggs begin to hatch and mothers can hear the babies in the eggs as they begin to call out. Both parents help them emerge from the eggs and the mother gently carries them to the water’s edge in her mouth. The hatchlings are capable of swimming right away and they follow their parents to a secluded area where the female will watch over them and keep them safe from predators. When the youngsters reach two years, they may leave to be on their own but are still in danger of predation, especially from larger crocodiles. Full maturity and size is reached between eight and 12 years of age.
Crocs usually move slowly, although they can reach speeds of up to 29 miles (54 k) per hour when running. Crocodiles can remain underwater for up to an hour. In the early morning crocodiles come out of the water and warm themselves in the sun. Crocs avoid overheating by allowing heat to escape through their mouths. Around noon, crocs enter the water to search for food, keeping an eye on what is happening within their territories. Crocodiles have advanced brains for reptiles, and they can remember and assess the daily behaviour of others. For instance, if an animal were to go to the riverbank at exactly the same time every day, the crocodile would learn that very quickly and if hungry, even lie in wait for that animal. Because crocodiles can move extremely quickly when needed, people living or vacationing near crocodiles are warned to vary their daily routines near water.
Because Nile crocodiles remain in the same territory throughout their entire lives, human encroachment can be a fatal disturbance—when their territories are taken over, crocodiles try to find a new home, but often die en route. Nile crocodiles are extirpated from Israel and the Cormoros islands.
Nile Crocodile Wildlife Fact File, IM Pub, US