The Nile crocodile (Crocodylus niloticus)

The Nile crocodile (Crocodylus niloticus) is one of three living crocodilian species in Africa—alongside the slender-snouted crocodile (C. cataphractus) and the African dwarf crocodile (Osteolaemus tetraspis). With seven recognized subspecies of Nile crocodile, these ancient reptiles trace their lineage back well over 200 million years, making them true prehistoric survivors.

Like their distant cousins the birds, crocodilians belong to the archosaur lineage and share several surprising traits: a four-chambered heart (rather than the three-chambered heart of most reptiles) and even a gizzard to help grind tough food. They split from other reptiles during the Triassic, evolving in parallel with the ancestors of dinosaurs and, eventually, birds.

Modern crocodilians fall into three families: Alligatoridae—which includes American and Chinese alligators plus South American caimans (eight species); Crocodylidae, the “true” crocodiles (fourteen species, including the Nile); and Gavialidae, represented today by the Indian gharial (Gavialis gangeticus).

Equipped with a bone-crushing bite and 64–68 razor-sharp teeth, Nile crocodiles can grow up to 6.1 m long and weigh as much as 900 kg. Every two years or so they shed and replace their teeth—up to forty-five times over a century—ensuring their jaws stay lethal throughout their long lives.

Females reach breeding maturity at around 10–12 years old. Each nesting season, a mother excavates a sandy hollow on the riverbank, lays between 25 and 90 eggs, and covers them for incubation. The sand’s temperature then determines each hatchling’s sex (warmer nests yield more females, cooler nests produce more males).

Crocodiles are cold-blooded ectotherms: by basking in the sun, they can raise their body temperature to about 38 °C—essential for digesting the large meals they swallow. At night, their temperature can drop to around 15 °C, slowing digestion until the next day’s warmth.

Mostly piscivorous, Nile crocodiles lie in wait by the water’s edge, ambushing fish and sometimes larger animals drawn to drink. Their teeth firmly grip prey but cannot chew; instead, they stash carcasses under debris and let them soften for days, then perform a death roll—using powerful tail thrusts to tear off chunks before swallowing them whole.

A special throat septum seals off water from the airway while feeding, and a second, transparent eyelid lets them see underwater without sacrificing protection.

Additional important info available at:

Furstenburg, D. 2008. Krokkodil Crocodylus niloticus. Game&Hunt 14(1):6-12. https://www.researchgate.net/publication/316167631_Crocodile_Crocodylus_niloticus