The name ‘hippopotamus’ comes from the Greek term for ‘river horse’. These huge mammals spend up to 16 hours per day submerged in rivers and lakes to keep cool and calfs can suckle underwater by closing their ears and nostrils. Hippos can hold their breath for up to five minutes and are very graceful in the water.
When on land they graze and can travel ten kilometres (six miles) in one night and consume 35 kilograms (80 pounds) of grass. When on the shoreline they secrete an oily red substance that acts as a sunblock. They are the third largest living land mammals and can grow to four metres (13 feet) long and 1.5 metres (5 feet) tall. They can weigh over 3,000 kilograms and have a lifespan of around 50 years.