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Pygmy hippopotamus

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The pygmy hippopotamus, scientifically known as Choeropsis liberiensis, is a unique mammal. It is a member of the family Hippopotamidae. This family includes only two living species. One is the massive common hippopotamus. The other is this much smaller, reclusive forest dweller.

ZooPygmyHippo
ZooPygmyHippo

Pygmy hippos are native to the forests and swamps of West Africa. They live primarily in Liberia. Small populations also exist in Sierra Leone, Guinea, and Ivory Coast. Because they are nocturnal, they are active mostly at night. This makes them very difficult for scientists to study in the wild.

To survive in dense forests, the pygmy hippo has several physical adaptations.

Pygmy Hippopotamus Skull
Pygmy Hippopotamus Skull

Their bodies are built for a terrestrial life, but they remain semiaquatic. This means they rely on water to keep their skin moist and cool. Their skin is greenish-black or brown, fading to creamy gray below. A thin epidermis covers a thick dermis. To protect themselves, they secrete hipposudoric acid. This substance provides a pinkish tinge to their bodies. It acts as both a sunscreen and an antiseptic.

Without water, their skin would quickly dry out and crack.

The pygmy hippo's body shape helps it navigate thick vegetation.

Pigmy Hippo 037
Pigmy Hippo 037

Unlike the common hippo, whose spine is parallel to the ground, the pygmy hippo has a sloping back. This allows it to move through dense plants more easily. Their bones are more gracile, meaning they are proportionally thinner. They also have longer legs and a longer neck than their larger relatives. Their feet are narrower with more spread-out toes. This helps them walk on the forest floor. Their skull also has less pronounced orbits and nostrils. This is an adaptation for spending less time in deep water.

Understanding the history of this species involves complex scientific debate.

Hexaprotodon liberiensis Lagos Zoo Portugal (3)
Hexaprotodon liberiensis Lagos Zoo Portugal (3)

Samuel G. Morton first classified them as Hippopotamus minor. He later decided they deserved their own genus, Choeropsis. In 1977, Shirley C. Coryndon suggested they were related to the extinct genus Hexaprotodon. This idea was widely accepted for many years. However, in 2005, Boisserie conducted a study of the phylogeny of Hippopotamidae. This is the study of evolutionary relationships. Boisserie found they were not part of Hexaprotodon. He returned them to the genus Choeropsis. The American Society of Mammalogists supported this move in 2021.

The evolutionary history of hippopotamids is a fascinating subject.

Anthracotherium magnum
Anthracotherium magnum

For a long time, scientists thought hippos were related to pigs. Later research at the end of the 20th century changed this view. We now know hippos are most closely related to cetaceans, such as whales and dolphins. They shared a common semi-aquatic ancestor. This ancestor likely split into two branches about six million years after the initial split from other animals. One branch led to whales, and the other led to anthracotheres. These were a large family of four-legged beasts. The oldest known hippopotamid is Kenyapotamus, which lived in Africa.

Pygmy hippopotamus pair
Pygmy hippopotamus pair

A specific group once lived in Nigeria, known as the Nigerian subspecies.

Pygmy Hippopotamus with the young
Pygmy Hippopotamus with the young

This subspecies was called Choeropsis liberiensis heslopi. It lived in the Niger River Delta. A British colonial officer named Ian Heslop collected specimens there in the early 1940s. He estimated that only about 30 individuals remained in the region. He sent four skulls to the British Museum of Natural History in London. In 1969, researchers identified these skulls as a separate subspecies. However, no reliable reports of these hippos exist today. Most scientists believe the Nigerian subspecies is now extinct.

The pygmy hippo faces significant threats in the modern world.

Pygmy hippos, Singapore Zoo
Pygmy hippos, Singapore Zoo

In 2015, the IUCN estimated fewer than 2,500 pygmy hippos remain in the wild. Habitat loss is a primary threat. Forests are often logged or turned into farmland. They are also vulnerable to poaching and hunting for bushmeat. War and natural predators also impact their survival. Because of these dangers, their survival in captivity is often more certain. They breed well in zoos, which provides much of our research data.

Zwergflusspferd - Pygmy Hippopotamus - Hexaprotodon liberiensis
Zwergflusspferd - Pygmy Hippopotamus - Hexaprotodon liberiensis

Protecting their forest homes is vital for their future.

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🖼️ Images & Media (12)
File:Hexaprotodon liberiensis Lagos Zoo Portugal (3).jpg
Hexaprotodon liberiensis Lagos Zoo...
File:Pygmy Hippopotamus Skull.jpg
Pygmy Hippopotamus Skull.jpg
File:Anthracotherium magnum.jpg
Anthracotherium magnum.jpg
File:ZooPygmyHippo.jpg
ZooPygmyHippo.jpg
File:Zwergflusspferd - Pygmy Hippopotamus - Hexaprotodon liberiensis.jpg
Zwergflusspferd - Pygmy Hippopotamus -...
Pygmyhippopotamus-uenozoo2008.ogv
File:Pygmy hippos, Singapore Zoo.JPG
Pygmy hippos, Singapore Zoo.JPG
File:Pigmy Hippo 037.jpg
Pigmy Hippo 037.jpg
File:Pygmy Hippopotamus with the young.jpg
Pygmy Hippopotamus with the young.jpg
File:Pygmy-Hippopotamus-Lisbon-zoo.jpg
Pygmy-Hippopotamus-Lisbon-zoo.jpg
File:Pygmy hippopotamus pair.jpg
Pygmy hippopotamus pair.jpg
File:Pygmy hippopotamus hungry.jpg
Pygmy hippopotamus hungry.jpg
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