Nile Crocodile

Mamba, Garwe, Ngwenya, Olom

Kingdom
Phylum
Subphylum
Class
Order
Family
Subfamily
Genus
SPECIES
Crocodylus niloticus
Population size
250-500 Thou
Life Span
50-80 yrs
TOP SPEED
35 km/h
WEIGHT
225-500 kg
LENGTH
3.5-6 m

The Nile crocodile is one of the largest crocodilian species. This reptile is a highly adapted aquatic predator. Females of this species are noticeably smaller than males. The body is streamlined, the tail is long and sturdy, and the hind feet of the animal are webbed. The reptile has long and powerful jaws, which perfectly fit catching and holding the prey. Due to a special valve, found at the back of their throat, these crocodiles can move under water with open mouth, grab and hold prey without ingesting water. The animal has grey-olive body and yellowish belly. Young crocodiles are identified by greenish or dark olive-brown coloration and black colored cross-banding all over the body and tail. As the crocodile grows up, the banding on its body becomes fainter.

Distibution

The Nile crocodile is widely distributed across Sub-Saharan Africa. The reptile most frequently occurs in the central, eastern, and southern regions of Africa as well as Western Madagascar. Being aquatic animal, Nile crocodile is typically found in rivers, large freshwater lakes, freshwater swamps, mangrove swamps as well as coastal estuaries.

Nile Crocodile habitat map

Climate zones

Habits and Lifestyle

The Nile crocodiles are solitary animals. However, they can occasionally be seen feeding in small groups, consisting of several individuals. They usually use a special technique, enclosing an area of water in order to concentrate fish within it. Then, dominance hierarchies decide, in what order the members of the group will feed. These reptiles are mainly nocturnal. By day, the crocodiles typically sunbathe or cool off in the water if needed. Male crocodiles are highly territorial; they patrol and defend their territories, which often include a part of the shoreline, extending about 50 meters into the water. Nile crocodiles usually dive for a few minutes, before they come to the surface; however, when threatened, they are able to remain submerged for up to 30 minutes. Moreover, when completely inactive, these reptiles are capable of holding their breath for as long as 2 hours. They are exceptionally fast runners, and in general, these crocodiles have very quick reflexes, but, unfortunately, tire quickly.

Diet and Nutrition

Being a carnivore, Nile crocodile feeds upon a wide variety of animal species, including insects, amphibians, fish and land mammals such as giraffes or Cape buffaloes. Newly hatched crocodiles usually start with insects, eventually going over to larger prey.

Mating Habits

MATING BEHAVIOR
REPRODUCTION SEASON
November-December
INCUBATION PERIOD
80-90 days
INDEPENDENT AGE
2 years
FEMALE NAME
cow
MALE NAME
bull
BABY NAME
hatchling
BABY CARRYING
25-80 eggs

Nile crocodiles have polygynous mating system, where one male mates with a number of females. Male crocodiles usually attract receptive females, making a wide variety of noises through bellowing, slapping their snouts in the water or blowing water of out their noses. Meanwhile, larger males are typically more successful in finding mates. The nesting season in this species occurs in November-December. During this period, a female crocodile digs a nest, which is a hole in a river bank or sandy river bed. Then, 25 - 80 eggs are laid and incubated for 80 - 90 days. When the hatching time approaches, the female opens the nest, carrying her offspring to the water. After a while, the young join a crèche of juveniles, which is looked after by females. The hatchlings can remain in this crèche for the first 2 years of their lives. Nile crocodiles are sexually mature at 12 - 16 years old.

Population

Population threats

The primary threats to this species have to do with humans. Thus, the reptile attracts hunters for its skin, which is used in production of high-quality leather. On the other hand, being large and dangerous predators, the Nile crocodiles face aggression from humans, who destruct their nests and frequently kill the crocodiles. Attempting to remove caught fish from fishing nets, these animals occasionally damage the nets, which lead to conflict between the crocodiles and fishermen. In Greater St Lucia Wetland Park in South Africa, the animals are threatened by invasion of exotic plants that shade and supplant their nesting sites, cooling their eggs, which can potentially bring to an all-female population.

Population number

Classified as Least Concern (LC) on the IUCN Red List, this reptile is currently not endangered. The overall estimated population of the Nile crocodile varies from 250,000 to 500,000 individuals.

Fun Facts for Kids

  • Sex of the future offspring greatly depends on the temperature of incubation: when the temperature is less than 31 degrees Celsius, the hatchlings are likely to be females, while temperatures over 31 - 34 degrees Celsius usually yield males. As the hatching time comes, the young give out a “peeping” call; the female hears the call and unearths the eggs, helping the hatchlings come out.
  • These crocodiles, together with their eggs, have been found in Egyptian tombs.
  • The ectothermic metabolism of these animals is highly beneficial for them. A large individual, weighing over 900 kg (2000 lb.), is capable of going over long periods of time without eating.
  • When hatchlings are threatened, the mother picks them up, taking them into her gular (throat) pouch, where they find protection.
  • Usually, both parents help the hatchlings come out of the eggs; they roll the eggs between their tongue and palate, cracking the eggs shell to make the escape easier for their offspring.

References

1. Nile Crocodile Wikipedia article - https://en.wikipedia.org/wiki/Nile_crocodile
2. Nile Crocodile on The IUCN Red List site - http://www.iucnredlist.org/details/46590/0

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