Animals Wildlife Are Hippos Dangerous? While they may appear harmless, hippos can be aggressive when provoked. Learn all about their behavioral patterns. By Jaymi Heimbuch Jaymi Heimbuch Twitter Writer California Polytechnic State University, San Luis Obispo Jaymi Heimbuch is a writer and photographer specializing in wildlife conservation, technology, and food. She is the author of "The Ethiopian Wolf: Hope at the Edge of Extinction." Learn about our editorial process Updated September 21, 2022 Share Twitter Pinterest Email An angry hippopotamus speaks up in Botswana. John Carnemolla/Shutterstock Animals Wildlife Pets Animal Rights Endangered Species The common hippopotamus (Hippopotamus amphibius), whose name comes from the Greek word for "water horse," is the third largest land animal after elephants and white rhinos. Despite its large size and innocent, sometimes sluggish appearance, it is fast and furious, both in the water and on land. In fact, it is considered one of the deadliest animals in Africa. The common hippo shouldn't be confused with the pygmy hippo, its much smaller relative. The pygmy hippo measures only five feet in length and three feet in height, compared to the common hippo's 16.5-foot maximum length and five-foot height. Common hippos weigh anywhere from 1.4 to five tons, while pygmies max out around 600 pounds. Behavior Hippos live in groups called schools or bloats (also named pods or sieges) and jostle for a position in the social ladder. They like to spend most of their time submerged in water, up to 16 hours per day, as this keeps their skin cool and moist. They do not have true sweat glands, but rather secrete a substance called "blood sweat" from their skin that creates a protective layer of mucous and prevents sunburn. It may also prevent infections from setting in to wounds while hippos lounge in filthy water. While the species is mostly sedentary, male hippos make efforts to assert their dominance after age seven. The roars and big yawns they make are actually aggressive displays, showing off their sizable and sharp teeth. They are able to open their mouths to an impressive 150 degrees and will often do this to size each other up, an act known as "gaping." Sometimes the sounds they make are incredibly loud, measuring up to 115 decibels, which is about what you'd hear if you were 15 feet away from speakers at a rock concert. Not only will hippos fight each other—particularly when their areas are crowded and they have to compete for resources—but they will also charge anything that is perceived as a threat. This includes cattle grazing nearby or people either on land or even when in boats traveling along a river. Hippos can run a surprising 19 miles per hour (30 kilometers per hour) for short distances, so it isn't easy to outrun one even on land. In the water, it can move at a speed of five miles per hour (eight kilometers per hour). Hippos are said to kill about 500 people each year. It is best to stay out of their territory; but if you do find yourself there, alert them to your presence by tapping on the boat, similar to how you would talk loudly in grizzly bear territory. Threats Despite the fact that hippos are so deadly to human, humans are the ones causing hippos to fast disappear as a species. The common hippo population in the Democratic Republic of Congo has declined by 95% since the beginning of the 21st century. This species is, unfortunately, very valuable to hunters for its meat, tusks, and hide. Following the 1989 ban on elephant ivory, demand went up for hippo ivory; apparently it is softer and easier to carve, which lends to its appeal. While hunting hippopotamuses is illegal, it is still a chief reason for the species' population decline. The IUCN Red List categorizes hippos as vulnerable. Because the species has lost vast portions of its habitat to human settlements and deforestation, many hippos are now confined primarily to protected areas. Once upon a time, they were native to 30 African countries and ranged all the way from the Nile Delta to the Cape of Good Hope. They're now extinct in the wild in Egypt, Eritrea, Mauritania, Algeria, and Liberia. Frequently Asked Questions How many people die from hippo attacks per year? It's unclear exactly how many people are attacked and killed by hippos per year, but most estimates put the number at 500. Almost all deaths related to hippo attacks occur in Africa. Who is at risk of a hippo attack? The vast majority of humans will never encounter a wild hippo in their lifetimes, which makes these animals relatively nonthreatening to people. Those who are at risk of a hippo attack, however, are people who fish in their territory in Africa. As demand for fish grows throughout hippos' range, an increasing number of attacks are reported. Can you outrun a hippo? Hippos can run 30 mph or more—faster even than the world's fastest human, Usain Bolt. That said, humans have no chance of outrunning a hippo. How can you prevent a hippo attack? The best way to avoid being attacked by a hippo is to keep your distance, avoid their territory, and make yourself known to them if they're near. If you're in a boat, tap on the boat just as you would talk out loud if you were in grizzly country. Do hippos eat people? Hippos are herbivores. They don't eat people or meat of any kind. They only attack humans as a means of self-defense.