Nile Crocodile (Crocodylus Niloticus
The Nile Crocodile is an unmistakable, cold-blooded, carnivorous apex predator, one that has been recorded on the Mara River at 26 feet (7.9 metres) in length overall, with males being thirty percent larger than females and weighing up to 2,200 lbs (1,000Kg). It is the second largest extant reptile in the world, after the saltwater crocodile (Crocodylus porosus
) and the largest in Africa.
Their armour-plated skin is covered with 'scutes' (scales) down their backs and tails. Nile Crocodiles vary in colour, according to their habitat; those with lighter coloured skin living in clean water, while those with darker coloured skin live in murky waters. That said, all Nile Crocodiles darken with age. Their eyes are green and have translucent membranes, to protect the eyes, like a third eyelid. They also have tear dusts, similar to a human, to provide tears - not through emotion, but for cleansing; thus the saying "crocodile tears". They have short, splayed legs, capable of carrying the larger ones at up to 9mph (14kph) in short bursts. Toes on the rear feet are webbed. Nile Crocodiles have their eyes, nostrils and ears situated on top of their heads, enabling them to stay 99% submerged.
Nile Crocodile have very large, long, flattened snouts, with a lower tooth fitting into a socket located in the top jaw and showing up through the top of its snout. Resident
Nile Crocodiles are seen in lakes, rivers and marshlands throughout Kenya. Rarely are they seen in saltwater areas, but can be found in river deltas and brackish lakes. Longevity
Nile Crocodiles lay approximately 50 eggs in an approximately 18" (45cm) deep hole, in the banks of the nearby waters, that is guarded by the female, who fasts for 3 months, while the eggs incubate. The temperature surrounding the eggs determines the sex of the young. Above 30C (86F) creates males and below, creates females. The emerging young have an 'egg tooth', used to break the shell. While they are doing so, they cry out and the mother, hearing this high-pitched call, helps to dig them out of the nest. On hatching, the 12" (31cm) youngsters head straight for the water. The young are protected by the female for up to two years, during which time they are mostly nocturnal, to avoid predation, but are not dependent on her for food. Only 10% of eggs survive to hatching stage, indicating that predation is heavy and possibly nests are flooded by rains or the adjacent waters. Only 1% of the hatchlings survive to adulthood, due again to predation and cannibalistic Crocodiles. Nile Crocodiles live up to 100 years of age. Predators
Nile Crocodile eggs are predated by Monitor Lizards
and possibly Mongooses. Occasionally, Marabou Storks
see Monitor Lizards attacking a nest and take over. Young Nile Crocodiles are preyed on by African Fish Eagles
and Yellow-billed Stork
, as well as some of the previously mentioned species of egg predators. There is little to predate fully-grown Nile Crocodiles, although many reports have been made regarding two scavenger predators, Nile Crocodiles and Lions, playing tug-of-war with carrion.
During the 1940 - 60 period, Crocodile skins were very much in demand for ladies shoes and handbags. This practice is now outlawed and indeed, frowned upon. Behaviour
Baby Nile Crocodiles grow at the rate of 12" (31cm) a year. Males become sexually mature at around 10 years of age, by which time they are approximately 10 foot (3 metres) long and become more territorial around females at 'breeding time', when the males slap the water with their snouts, blow water through their nostrils and bellow. Nile Crocodiles mate in the water, 'Lion-fashion', with the male roaring and holding the female under water. Around 6 weeks later, the female makes her 'nest' in a sandy bank', laying and covering over the eggs.
Nile Crocodiles are sociable, gathering sometimes in number, to bask on a river bank or share in a food source - often herding large Catfish.
During sunny periods, Nile Crocodile bask with their mouths open, to keep cool. Those at Lake Turkana rarely bask, however, preferring to lie in the shallows. They are capable of staying submerged for up to 2 hours, or 30 minutes if swimming, which they are capable of doing at up to 22mph (32kph), three times faster than a human.
There is an hierarchy, substantiated by size and only on rare occasions is this challenged, resulting in bloody battles that can result in death. Diet
Baby Nile Crocodiles eat insects and frogs, moving up the food-chain as they grow and are eventually able to take just about any animal, with African Buffalo
and Black Rhino
recorded as being killed by Nile Crocodiles. Even Lions
, taking a drink, have been ambushed by these formidable reptiles. Although they mostly feed on fish and other reptiles, they also take wading & swimming birds, as well as mammals. The Great Migration is well-recorded, where Crocodiles take large ungulates like Zebra
, holding them down in the water to drown, then hiding the carcass underwater to soften it. Much of their food is from carrion, in particular dead Hippos
, where several Nile Crocodile congregate to feed.
Nile Crocodiles can last for months without food and can show tremendous patience before ambushing their prey - rarely do they go 'hunting'. When they do eat after long periods of going without food, they can consume up to half their body-weight.
Crocodiles have the strongest jaws of any animal, over ten times more powerful than a Great White Shark and designed to clamp and bite through tough hide and bone. Surprisingly, the muscles used to open the jaw are so weak, a human can easily hold the jaws shut. Their 66 sharp teeth are cone-shaped and the grip is almost impossible to break. And any broken-off teeth are replaced during much of their lives. The teeth are used mainly to rip food, swallowing chunks at a time. If the prey is light and there is more than one Crocodile, they each grip and complete a 'death roll', to tear off chunks of food.
Nile Crocodiles are considered to be the biggest killer of human beings by animals, with around 500 reported deaths per annum. Most deaths are due to humans and Nile Crocodiles living in such close proximity along waterways. Other Nile Crocodile Facts
Nile Crocodiles, unlike other reptiles, have a four-chambered heart, closely relating them to birds
A crocodile cannot stick its tongue out.
Crocodiles have webbed feet, which it tucks by its side, to make it streamlined when swimming, sticking one out, to make a fast turn.
The scientific name for Nile Crocodile (Crocodylus niloticus
) is derived from the Ancient Greek kroko
("worm") - and - niloticus
, referring to the Nile River. Photographs
Images taken in Kenya's Lake Baringo, Haller Park (Mombasa), Mamba Village (Nairobi), Masai Mara, Nairobi National Park and Olara Orok Conservancy.