The water leguaan is Africa's most widespread goanna. It lives anywhere there that fresh water meets the land, from the Nile delta down to the Cape of Good Hope. It is grey to grey-black in color, with white or light yellow markings and underside. Its form is streamlined, with a long highly keeled tail for swimming. Its head and jaws are robust, although not as powerful and boxy as Africa's other leguaans. Like the other leguaans, however, its teeth are adapted for crushing rather than ripping. It dens in burrows, hollow trees, or among tree roots. This species is quite security conscious. Alert and wary, it is difficult to approach and defends itself ferociously if cornered. Once it bites it holds on, often for up to an hour. In the Europe and the Americas, this species is known as the Nile monitor.
Water leguaans are opportunistic foragers, happily eating anything they can catch and overpower. Their semi-aquatic lifestyle means they eat a lot of shellfish and fish, but they also take waterfowl, rodents, snakes and lizards, small turtles, birds eggs and hatchlings, insects, worms, and carrion. They are pests around human garbage, often getting into or knocking over garbage cans in search of food. The water leguaan is well known for its love of crocodile eggs. Crocodiles are among the most protective mothers in nature, guarding their nests with patience and ferocity, yet the wiley water leguaan can often slip past these much larger and more powerful guardians to feast.
Water leguaans do well around humans, tolerating their houses and farms, raiding their garbage and poultry, and avoiding these bipedal apes whenever they see us. They feature prominantly in myth and legend throughout their range, and are often credited with warning of the presence of crocodiles (hence the name Monitor, for Warning). The skin of the water leguaan is nearly useless for leather, so they are spared systematic persecution, but the hatchlings are caught in huge numbers for the international pet trade. Unfortunately, the water leguaan makes one of the worst pet monitors alive (only the Komodo dragon is less suitable). They are paranoid around humans, almost never coming to trust us and more than willing to defend themselves with tail blows, claws, bites, and projectile defication when they feel threatened. In addition, the cute, attractively marked and inexpensive hatchlings grow into enormously powerful monsters requiring an immense and extra sturdy cage, baking tropical heat, large amounts of food, and the large adults are capable of killing and eating the family cat. The vast majority of the hatchlings sold as pets end up dying of neglect. This has little impact on the species as a whole, however, since water leguaans are both fecund and fast growing and can rapidly replace these losses.
Typical adult water leguaans are Medium or Large sized. Occasionally, one will grow to Huge sizes.