Herbivores or meat-eating predators?

A startling revelation about Hippos

by Annette J Beveridge

Unpredictable and aggressive, hippos are known to be one of the most dangerous animals in the world but new research has revealed a dangerous new edge to these animals.

Hippos are responsible for about 500 human deaths each year and as they are highly territorial, they will also come into conflict with other animals. The canine teeth which grow up to 20 inches in length is used for fighting off predators and used against other hippos.

Research confirms that these herbivores will also predate upon other animals too.

These are huge animals growing to more than 10 feet in length and up to five feet at the shoulder. Hippos weigh between 3,000 and 10,000 pounds. The females are smaller and weigh about 3,000 pounds on average.

These animals may appear docile but mood can turn in an instant. Jaws open to 180 degrees and clamp down with a force that far exceeds that of a human. A hippo is able to hold its breath under water for up to five minutes and this makes it difficult to detect its presence. On land, despite its weight, hippos can run up to 20 miles an hour.

Meat-eating predators

In a paper published in the journal Mammal, researchers argue that meat-eating may not be as unusual as first thought. Hippos have fed upon impalas, elephants, zebras, wildebeest and even, other hippos.

In fact, hippos in captivity have killed and eaten flamingos, wallabies, and pygmy hippos but this behaviour is not always seen because they are most active at night.

During its evolutionary process, a herbivore like a hippo is adapted for a plant-based diet. Microbes within the gut ferment and digest the plant material. Hippos are exposed to outbreaks of anthrax when they inhale bacterial spores on plants, but will also consume them while feeding on any contaminated carcass. At times, cannibalism outbreaks can make the problem worse.

Hippos are a keystone species. The behaviour and activities while foraging has an important impact on both land and aquatic ecosystems. The tendency to feed on carcasses - including on the carcasses of other hippos has a significant implication for ecology.

The scavenging behaviour of these animals may explain why the species mortality from anthrax is higher than those of anthrax-susceptible populations of ungulates (mammals with hooves).