Understanding Hippos

Hippos, although they breathe air, are more relaxed underwater and can hold their breath for up to six minutes. They have nails instead of hooves and prefer to keep their feet on the bottom as they can't swim well. Underwater, they are virtually weightless and move using a space-walk-like motion. On land, hippos can move quickly over short distances. They communicate underwater using sounds similar to dolphins, which is not surprising as they share a common ancestor with dolphins and whales.

What is a unique feature of hippos that allows them to stay underwater for extended periods?

• They can absorb oxygen through their skin.

• They have special air sacs.

• They can hold their breath for up to six minutes.

• They have gills like fish.

Why do hippos prefer walking on the riverbed instead of swimming?

• They are afraid of water.

• They can swim faster than they can walk.

• They are virtually weightless underwater.

• They have webbed feet.

How do hippos manage to hear and communicate underwater?

• They use their eyes to communicate.

• They have special valves that close their ears.

• They produce sounds through closed airways.

• They use sign language.

What is surprising about hippos' movement on land?

• They are very slow and sluggish.

• They are excellent distance runners.

• They can fly short distances.

• They can move quickly over short distances.

What recent discovery has been made about hippos' evolutionary history?

• They are a type of prehistoric fish.

• They share a common ancestor with dolphins and whales.

• They are closely related to elephants.

• They evolved from large land mammals.

What sound do hippos make that is similar to another marine animal?

• They click like dolphins.

• They whistle like whales.

• They roar like lions.

• They chirp like birds.