Nile Crocodile (Crocodylus niloticus)
Order: Crocodolia, Family: Crocodylidae
Average weight: between 600 and 2,000 pounds.
Nile crocs are characterized by their lizard-shaped bodies and scaly hides.
Coloring: ranges from drab green or brownish to a blackish tone on the dorsal side, much lighter on the ventral side.
The eyes and nostrils of crocodiles are situated on the top of the head so they can see and breathe while the rest of their body remains almost totally underwater.
In the water, crocs have large, oar-like tails that they use to swim. Only their rear feet are webbed, and they are rarely used in movement underwater.
II. GEOGRAPHICAL RANGE AND HABITAT:
- Average weight: between 600 and 2,000 pounds.
- Nile crocs are characterized by their lizard-shaped bodies and scaly hides.
- Coloring: ranges from drab green or brownish to a blackish tone on the dorsal side, much lighter on the ventral side.
- The eyes and nostrils of crocodiles are situated on the top of the head so they can see and breathe while the rest of their body remains almost totally underwater.
- In the water, crocs have large, oar-like tails that they use to swim. Only their rear feet are webbed, and they are rarely used in movement underwater.
- On land, crocs walk on their short, seemingly weak legs. They bring their legs in close to their bodies and lift themselves high off the ground when walking.
- Nile crocs can move at speeds of up to 29 miles per hour. They have even been observed "galloping," like rabbits. They plant their front feet, bring their hind legs around the outsides of the front legs, plant them and then push off with their front legs.
- Africa and on some islands, including Madagascar.
- The Nile crocodile inhabits any wet area in tropical zones of Africa. In lakes, rivers, marshes and ponds, the Nile crocodile is the most common and widespread crocodile.
IV. LIFE CYCLE/SOCIAL STRUCTURE:
- The Nile crocodile will eat almost anything. Hatchlings eat insects and minnows and, as they grow, move on to consume crustaceans and large fish.
- Mature Nile crocodiles eat anything from fish and turtles, which they crack open with their powerful jaws, to larger mammals including baboons, hyenas, impalas and wildebeest. It is not uncommon for these predators to kill and devour large and surprising prey, such as young hippopotamuses, buffalo, giraffes, and even lions and porcupines.
- Nile crocs are strictly carnivorous, but they have reportedly been spotted eating vegetation, although this has not been verified.
- Although not common, Nile crocs have been known to kill and eat humans.
V. SPECIAL NOTES/ADAPTATIONS:
- The Nile crocodile lives in large communities ranging from a few dozen to a few hundred individuals, depending on their habitat.
- Although they live together, Nile crocs do not engage in group behaviors other than large feeding frenzies in which all the crocs near a large prey animal converge on it and feed together with surprisingly little fighting.
- There is a social hierarchy in the crocodile community, with larger crocs, ususally male, dominanting.
- Crocodiles rarely venture far from the water. Only if its pool is drying up will a Nile crocodile seek a new home, and when this happens the individual usually dies en route.
- Nile crocodiles mate late in the year. The male crocodile performs elaborate mating displays, much like birds do, and then approaches any receptive females. During copulation, which only lasts a minute or two, the pair usually sinks to the bottom of the lake or river.
- The female is usually ready to lay her eggs about two months later. Then she lays a few dozen heavily calcified, chicken-sized eggs in the hole. It is said that she lays each egg on her hind foot and carefully lowers it into the hole.
- The eggs stay in the nest, with its rotting debris creating a constant temperature of over 95 degrees, until they hatch, at which time the hatchlings call for their mother. She comes and carries the young in her mouth to the water.
- Mother Nile crocodiles often take their young to out-of-the-way, backwater areas of their lake or river and protect them for up to two years.
- At 2 years of age, the young move off to be independent.
- They reach sexual maturity around 8 to 12 years old.
VI. ENVIRONMENTAL IMPACT:
- All crocodiles have a flap of skin at the back of their throat that closes off their respiratory system when they are underwater. This allows them to open their mouths underwater without choking.
- Unlike other reptiles, crocodiles have external ears that close, along with the nostrils, when they dive.
- Another feature that helps the crocodile survive in the water is its third eyelid, the nictitating membrane. When a croc dives, it closes the transparent third eyelid to keep water out of its eyes without sacrificing its vision.
- Nile crocodiles have been observed using their long tails to corral a small school of fish. This disorients the fish, and makes it easy for the crocodile to catch them.
VII. POPULATION STATUS:
- The Nile crocodile is known to eat domestic cattle if given the opportunity. One farmer reported losses upward of 150 head of cattle to Nile crocodiles in one year. They also occasionally kill humans.
VIII. MORE FACTS ABOUT THE CROCODILE:
- Although not endangered and perhaps not even threatened, the Nile crocodile is very vulnerable to human intrusion in the form of water pollution, poaching and land development. Unlike many animals, crocodiles cannot adapt to a change in habitat type. The Nile crocodile's currently healthy numbers could be affected given too much human intrusion.
- Their skin, unlike that of most reptiles, grows with them and is not shed.
- Sometimes, in an effort to anchor their prey, crocs wedge an animal between rocks or tree roots to hold the prey firmly so the crocodile can tear off a chunk. Some think that this intelligent behavior borders on a primitive form of tool use.