Hippos can spend up to 16 hours a day submerged in river and lakes to keep themselves cool. They can hold their breath underwater for up to 5 minutes, but they are usually big enough to walk or stand on the lake floor. Their eyes and nostrils are located high on their head that lets them see and breathe while mostly submerged. They travel at night in single file and eat up to 80lbs of grass. They secrete an oily red substance that can look like blood but it is a skin moisturizer and sunblock that helps protect against germs. They are prime prey for crocodiles, hyenas and lions. Their name in Greek means “river horse”.