The Nile crocodile is covered with hard, bony plate like scales which are coloured a dark or olive grey on the top with dark bands which run across the back. On the underside they are a cream or yellow colour with black patches.
Their streamlined long body ends with a narrow jaw at one end which has visible teeth sitting on the outside of the mouth at all times. On the head the eyes, nostrils and ears sit on top of the head. This allows these to sit out of the water so they can see and breathe while the rest of their body is safely below the surface.
Their tail is long and muscular. On top of the tail is pairs of raised keeled scales which run down the length of the tail. The tail is used to push them forward in the water. They also have webbed feet which can be used to assist with swimming.
When swimming they have a third eyelid which is clear and covers the eyes so they can still see while swimming.
Nile crocodiles are the second largest species of crocodile on Earth. They can grow up to 5m (16.4ft) long and weigh an average 410kg (900lbs). Some exceptionally large crocodiles have been found that are up to 6m (19.6ft) long and weigh 900kg (2,000lbs).
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The Nile crocodile is a carnivore. The majority of their diet is fish but adults will also eat antelope, ostrich, baboon, zebra and buffalo. On a rare occasion they can eat larger prey such as giraffe, rhino or young buffaloes and hippos.
Adult Nile crocodiles are the apex predator within their environment.
On occasion they will store large prey items under logs or overhanging banks and return to eat them over a few meals.
While mostly solitary, groups of Nile crocodiles have been observed to come together and work collectively to take down larger prey or to easier catch large schools of fish.
The Nile crocodiles jaw is not designed for chewing food. Instead they will drag prey items in to the water and they then roll in the water to tear chunks of flesh off which they can swallow.
The Nile crocodile is a native of Africa. They have a wide range across the continent being found in most of Central and Southern Africa along with the Nile river valley. They are also found on the Island of a Madagascar.
The full list of countries they inhabit is Angola, Benin, Botswana, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Congo, The Democratic Republic of the Congo, Côte d'Ivoire, Egypt, Equatorial Guinea, Eritrea, Eswatini, Ethiopia, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Kenya, Liberia, Madagascar, Malawi, Mali, Mauritania, Mozambique, Namibia, Niger, Nigeria, Rwanda, Senegal, Sierra Leone, Somalia, South Africa, South Sudan, Sudan, Tanzania, Togo, Uganda, Zambia and Zimbabwe.
Nile crocodiles spend most of their life in the water. They are able to live in lakes, marshes, rivers, estuaries, swamps and mangroves.
Due to their large range the timing of the breeding season is highly variable. Typically it takes place around the end of the year in November or December.
Following a successful mating the female will find a spot on the sandy bank of their river home and dig a hole which may be up to 50cm (19.7in) deep. Once this nest site is established the female will use the same site each year. In to this hole she will deposit anywhere between 16 and 80 eggs. These are then covered over with sand.
The female remains by the nest to guard against predators while the eggs incubate. This process takes around 90 days and depending on the temperature at which the eggs incubate the hatchlings will either be male or female. Females are produced in cooler weather and males in warmer periods.
Just before they are ready to hatch the hatchlings will start to call. At this point the female will dig them up and if any eggs have difficulty hatching she will place them gently in the mouth to crack them open.
While females work to defend the nest they must return to the water at times to cool off. When they do this opportunistic scavengers such as hyenas and lizards may eat the eggs.
Once the crocodiles emerge from the nest the mother will gather them in her mouth and carry them to the water.
After entering the water the crocodiles will spend the next 6-8 weeks swimming together for safety before starting to disperse.
Sexual maturity is tied to size and can be reached at different ages. Males reach maturity at 3.1m (10.2ft) while females reach this at 2.6m (8.5ft).
When Nile crocodiles are warm they will sit on the banks of a river with an open mouth. This open mouth will help lose the excess heat through the mouth lining.
Nile crocodiles have a social structure with larger individuals being more dominant. In times where they hunt together the most dominant crocodile will take the most food.
A group of crocodiles is known as a Bask, Congregation, Float, or Nest.
If their water source drys up the Nile crocodile may move to a new water source or estivate. To estivate they dig a hole in the wet mud on the banks which then drys around them and helps to protect from extreme temperatures. In this time they will not eat or drink. Once it rains they will emerge.
Nile crocodiles are capable of walking on land and they stand up on their legs to achieve this. While mostly slow they are capable of reaching 15km/h (9mph) for short periods.
Predators and Threats
As the apex predator in their environment the adult crocodile does not have any natural predators apart from humans.
They help their environment by keeping down fish numbers so no species becomes overpopulated and removing dead animals from the water.
Threats to their survival include habitat destruction, hunting and pollution of their environment. Due to their large range these are not a major threat to the species as a whole and their population remains stable leading to them being listed as least concern.
Hunting in the early 20th century did almost drive the species to extinction. They were used for leather and meat.
Their scientific name translates as ‘pebble worm of the nile.’
The nile crocodile is the second largest crocodile on Earth after the Saltwater Crocodile (Crocodylus porosus).
Gianfranco Gori / CC BY-SA (https://creativecommons.org/licenses/by-sa/4.0)
Photo by Derek Ramsey (Ram-Man) / CC BY-SA (https://creativecommons.org/licenses/by-sa/2.5)
Sarah McCans / CC BY (https://creativecommons.org/licenses/by/2.0)
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