Dwarf Crocodile

Classification and Evolution

The Dwarf Crocodile is a small species of crocodile natively found in the rainforests of West Africa. The Dwarf Crocodile is the smallest species of crocodile in the world and is also one of the most distinctive with a short, broad snout and tough scales that cover their entire black body (most crocodiles do not have such armored scales on their underside). These characteristics have led to the Dwarf Crocodile being known by a number of different names including the Broad-Snouted Crocodile, the Bony Crocodile and the Black Crocodile.

Although Dwarf Crocodiles are commonly found in parts of their natural range, their numbers in others have declined mainly due to habitat loss and hunting.

Anatomy and Appearance

The Dwarf Crocodile rarely grows to more than 1.6 meters in length with the largest known individuals reaching a maximum length of 1.9 meters. The body of the Dwarf Crocodile is black with a yellowish underside and is protected by tough, armored scales, which are bony plates that not just protect it from injury but also prevent the animal from getting burnt by the hot sun.

The Dwarf Crocodile has a number of adaptations that aid it when in the water including their vertically flattened, muscular tail that is used to propel their bodies when swimming and webbing between their toes which helps them to negotiate the slippery banks. Their eyes and nostrils are located on the top of their heads to enable the Dwarf Crocodile to both see and breathe whilst the rest of its body is submerged, allowing it to both watch for prey and predators almost completely hidden.

Types of Dwarf Crocodiles

There are two recognized species of Dwarf Crocodile which are the West African Dwarf Crocodile and the Congo Dwarf Crocodile which differ slightly in not just their location, but also in their appearance and behavior.

• West African Dwarf Crocodile – Osteolaemus tetraspis – These reptiles grow to be just under 6 feet long and are the smallest croc in the world.
• Congo Dwarf Crocodile – Osteolaemus osborni – Also known as “Osborn’s dwarf crocodile”, this subspecies is named after an American paleontologist Henry Fairfield Osborn.

Distribution and Habitat

The Dwarf Crocodile is found throughout a number of different countries in West Africa including Angola, Cameroon, Congo, Gambia, Ghana, Guinea, Liberia, Nigeria, Senegal, and Sierra Leone although the populations vary drastically in number between the regions. Dwarf Crocodiles tend to be found in slow-moving rivers in areas of dense rainforest along with swamps, permanent pools of water and seasonal floodplains.

Despite being specially adapted to life in the water, Dwarf Crocodiles also spend a lot of time on land where they dig burrows in the river bank to rest during the day. However, they are severely threatened by the loss of their habitats throughout much of their natural range primarily in the form of deforestation for logging, clearing land for agriculture, and making way for growing human settlements.

Behavior and Lifestyle

Using the dark of night, Dwarf Crocodiles are nocturnal and hunt both in the water and on the banks in the dark looking for prey and usually solitary. During the day they rest in burrows which are dug into the ground of the river bank. These are accessed through small entrances and tunnels which can be several meters long. If they cannot find a good place, Dwarf Crocodile will hide amongst submerged tree roots that hang into the water.

The Dwarf Crocodile is a cold-blooded animal meaning that it has to sunbathe to warm its body up, give it the energy to hunt, and enter the water to cool it down. When in the water, Dwarf Crocodiles sink their bodies down below the surface so that only their eyes and nostrils are exposed so they are able to hide from potential predators and ambush unsuspecting prey.

Reproduction and Life Cycles

Dwarf Crocodiles tend to breed at the beginning of the wet season (May – June) when a male will mate with several females that share his territory. The female then builds a nest by dragging rotting vegetation together to create a mound where she lays up to 20 white, leathery eggs. As the vegetation decomposes it releases heat which helps to keep the eggs warm whilst incubating.

Female Dwarf Crocodiles will fiercely guard their eggs from predators until they hatch three months later, when the young call to her and she digs the them out of the mound to help them escape (they are even known to gently roll eggs that haven’t yet hatched around in their mouths to crack the shell). The mother then gently picks her young up in her mouth and carries them down to the water ensuring that they get there safely. Although Dwarf Crocodiles are usually independent of their mother very quickly, some are known to stay close to her for at least a few weeks for safety.

Diet and Prey

It may come as no surprise, but these diminutive crocs are carnivorous animals, and they usually look for fish, birds, crustaceans, frogs, and toads to make up the bulk of their diet along with the occasional small mammal. Dwarf Crocodiles snap their strong jaws shut to catch their prey, secured by a powerful bite from their cone-shaped, razor-sharp teeth.

Unlike a number of other animal species, Dwarf Crocodiles continuously regrow and replace their old teeth which are pushed out by the new ones that develop below. They are however, unable to chew food and so must rely on tearing their prey into pieces that can then be swallowed whole. In areas where seasonal flooding occurs they are known to change their diet depending on the rains, eating more fish that are readily available with the floods and feeding more on crustaceans during the dry season.

Predators and Threats

Despite being a powerful predator itself, the small size of the Dwarf Crocodile means that it is an easier target than its much larger relatives, with other crocodiles being the biggest threat to adults. The young and eggs, however, are preyed upon by a number of different animals including birds, mammals, and other reptiles despite the fierce guarding of them by their mother.

The biggest threat though to Dwarf Crocodiles throughout much of their natural range today is people, primarily in the form of habitat destruction for timber and use of the land for agriculture including creating large plantations of oil palms. Dwarf Crocodiles are also hunted by local people in certain areas for food, with their tough skins then being used in the making of certain local products.

History and Evolution

Like other members of the crocodile family, the Dwarf Crocodile is an ancient species that is thought to have changed very little in the last 65 million years. Their semi-aquatic nature means that they have a number of distinctive features that help them to live and feed in the water including a transparent third eyelid that can be closed to protect their eyes when under the water. They have flaps of skin that can be closed to cover the windpipe and ensure that water doesn’t enter their lungs (which means that water doesn’t go into their windpipe when they open their mouth to catch prey), along with similar flaps that cover their nostrils and ears. People once thought that Dwarf Crocodiles were cannibals because the mother carries the young in a throat pouch in her mouth, to get them to the water safely.

Relationship with Humans

Unlike a number of their larger relatives, the tough, armored skin of the Dwarf Crocodile has meant that they are not hunted so frequently as other crocodile species, but they are often hunted for their meat by local people in certain areas. Dwarf Crocodiles are also affected heavily by growing levels of human activity throughout much of their natural range as they lose their habitats to forest clearance for the timber industry and to make way for agricultural plantations like palm oil. Along with the growing size of local settlements, the clearance of rainforest to produce grazing for livestock has also meant the loss of large chunks of their once vast natural range and can cause conflict between these reptiles and farmers that fear for their animals.

Conservation Status and Life Today

Today, the Dwarf Crocodile is listed by the IUCN as being an animal that is Vulnerable in its natural environment with an estimated 25,000 – 100,000 individuals thought to be left in the wild. However, population data is often hard to collect and although they are heavily exploited in certain areas, the Dwarf Crocodile still has quite a wide distribution throughout a number of countries in West Africa. The Dwarf Crocodile is still known to be locally abundant in some areas including parts of Cameroon, however, there have been severe population declines in others primarily due to the drastic loss of vast regions of their natural habitats.