Cover Image by Malcolm Macgregor (CC 3.0)
The Hippopotamus is considered the second heaviest land mammal (7000 lb/3200 kg), behind elephants (13,000 lb/6000 kg). There is debate if it is the second or third largest land mammal since the rhinoceros (5000 lb/2300 kg) can stand taller at 6 feet (1.8 m) compared to a hippo at 5 feet (1.5 m) but not weigh quite as much. The ancient Greeks called the Hippopotamus the ‘River Horse.’ The name Hippopotamus can be broken down to hippo, meaning horse in ancient Greek, and potamus, meaning river in ancient Greek. These semi-aquatic mammals originated in the rivers, streams and lakes of the African Continent.
There are two main species of Hippopotamus:
The range of the Common Hippo was the lower 2/3s of Africa and up the Nile River into Egypt. Due to human activity their range has drastically shrunk and the main populations still survive in East and Southern Africa. There is also a small population (~ 50 animals) that established themselves in Colombia in South America.
The Pygmy Hippo’s range is West Africa in the Liberia, Sierra Leone, and Cote d’Ivorire. Populations were found in Nigeria, but no sightings have been seen since 1945.
For many years, scientists thought Hippos were closely related to pigs due to similar teeth (molars). More recent DNA evidence suggests Hippos are actually more closely related to cetaceans (whales/dolphins). It is believed Hippos and Whales/Dolphins shared a common ancestor that lived nearly 55 million years ago. One offshoot of this species went to the water and the other remained on land.
The Common Hippo is currently listed by IUCN as Vulnerable with an estimated population of 115,000 to 130,000. These animals are killed by humans for their teeth (ivory). However, currently the populations appear to be stable.
The Pygmy Hippo is listed as Endangered with a population of around 2,000 animals. They are expected to continue to decline by 20% in the next 50 years.
Hippos are considered a vital species to the health of the African Continent’s fresh water rivers, streams, and lakes. They have been called the “Life Force of African Rivers,” due to their feces providing nutrients for many other species (ie. fish and insects).
These animals have many special adaptations to survive in Africa’s harsh environment:
- Can live up to 40 years in the wild (50 years housed under human care)
- Heavy set bones to support their weight, called ‘graviportal’
- Stay mostly in water during the day and forage at night
- Can run up to 19 mph (30 kph)
- Great swimmers, hold breath for about 5 minutes under water
- Acute underwater hearing
- Can vocalize both above and under water, and even do both simultaneously
- Eat roughly 1.5% of their body weight per day
- Reports of eating meat, more opportunistic feeding behavior, so still considered herbivores
- Clear paths for other animals down to waterways
- Sweat is red, often called “blood sweat”
- Female hippo’s milk is colored pink
Last Fact is Jon makes much better Hippo calls than Angie and here he is celebrating!
The Pygmy Hippo is the one species most under threat. However, climate change and now proposals to cull hippos for trophy hunts is only hurting these populations of Common Hippos. Considering how critical hippos are to healthy fresh water ecosystems in Africa, this species deserves much more attention than it is currently receiving.
To help our fresh water please consider these 45 ways to conserve water in the home and yard.