The hippopotamus looks like a lazy river cow — and is actually one of Africa's most formidable animals, with jaws that open 150 degrees and a surprising turn of speed.
Here's the truth about the 'river horse.'
The name hippopotamus comes from Greek for 'river horse,' but hippos' closest living relatives are actually whales and dolphins.
Hippos are the third-largest land mammals after elephants and rhinos; big males can weigh 3,000-4,000 pounds (1,400-1,800 kg) or more.
Despite living in water, hippos can't truly swim or float — they walk and bounce along the bottom of rivers and lakes.
Hippos can hold their breath for around five minutes, and sleeping hippos surface to breathe automatically without waking.
Hippos secrete a reddish, oily fluid nicknamed 'blood sweat' that acts as sunscreen and antibiotic — they don't actually sweat.
A hippo's jaws can open about 150 degrees, with lower canine tusks that grow over a foot long.
Hippos are widely considered among Africa's most dangerous large animals, killing an estimated several hundred people per year.
On land, a hippo can outrun a human over short distances, reaching roughly 19-25 mph (30-40 km/h).
Hippos spend up to 16 hours a day in water and emerge at night to graze, eating around 80 pounds (35 kg) of grass.
For their size, hippos eat modestly — their sluggish daytime lifestyle keeps energy needs surprisingly low.
Hippos mark territory by spinning their tails while defecating, spraying dung in all directions.
Calves are born underwater or on land and can nurse underwater by folding their ears and closing their nostrils.
The common hippo's smaller cousin, the pygmy hippo, survives only in West African forests and is endangered.
Hippo pods churn nutrients through African rivers; their dung supports fish and aquatic ecosystems downstream.
A famous escaped population of Pablo Escobar's hippos now breeds in Colombia's rivers, one of the world's oddest invasive-species stories.
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