Dwarf crocodiles are best known for their small stature, with few growing larger than a medium-sized dog, but they are also known for their dark coloration. In adults, the head and tail and the top and sides of the body are predominantly charcoal-colored, and the underside is light yellow. As in other crocodile species, the outer layer of the hide is covered with thick scales made of keratin. The hide of juvenile crocodiles is also dark but with yellow bands on the top and sides of the body. Dwarf crocodiles are sexually dimorphic in that males tend to be heavier than females.
Dwarf crocodiles reproduce during the rainy season, which typically lasts from June to October. During the early part of this period, males will make low-pitched drumlike vocalizations to attract mates, and individual males may fight with one another for females. After mating, a female dwarf crocodile builds a mound-shaped nest several meters away from the water’s edge. She deposits 10–20 fertilized eggs in the mound, which she guards while incubating the eggs for roughly three months, until they hatch. The mound is made up of fallen leaves and other vegetational debris, whose decomposition serves as a heat source that aids incubation. The calls of newly hatched young prompt the mother to excavate the mound to free them before transporting them to the water. Young dwarf crocodiles will remain in their mother’s care (and possibly their father’s) before they disperse. Individuals of both sexes become sexually mature between ages 5 and 6. Some sources report that dwarf crocodiles may live as long as 50–100 years in the wild (see alsolife span).
Since 1996 the IUCN has considered the dwarf crocodile to be a vulnerable species. Although it occurs widely throughout West Africa—numbering from 25,000 to 100,000 individuals, according to estimates—many local populations and habitats have been reduced by human activity. Dwarf crocodiles are hunted for their hides and meat in some regions and killed as pests in others. Moreover, a substantial amount of their habitat throughout the region has been lost to logging, oil palm cultivation, and expansion of grazing land. Several individuals live in zoos and on ranches throughout the world.