Dolphins can 'stay awake for 15 days', says US study

Dolphins can stay awake for 15 days or more - by sleeping with one half of their brain at a time, scientists have learned.

Researchers in America tested two bottlenose dolphins' responses to echoes as they swam around a pen.

 

The mammals kept going for five days non-stop in three separate tests, and one even managed 15 days in another trial.

 

Experts think the ability is an important survival skill for dolphins. It means they can surface to breathe when they need to and keep watch for shark attacks.

 

Dolphins use sound waves to find their way, hunt prey, detect predators and organise groups.

 

 

Match the words below to their definitions

 

echoes / mammals / predators / responses / surface / survival

 

1. reactions to something
2. when sound reflects off something and you hear it again
3. animals that produce milk to feed their babies
4. when someone or something continues to live or exist, especially after a difficult or dangerous situation
5. rise to the top of a body of water
6. animals that kill and eats other animals

 True or false?

 

1. There are two halves to a dolphin brain.

2. Dolphins can’t remain awake for long periods of time.

3. Dolphins always stay awake for 15 days.

4. Dolphins hunt other animals.

5. The researchers studied dolphins in the wild.

6. Sound waves help dolphins navigate.

7. Experts don’t know why dolphins stay awake so long.

8. Sharks sometimes attack dolphins.

 

 What's the missing word?

 

 1. Researchers in America____________________two bottlenose dolphins' responses.

 2. One even_______________15 days in another trial.

 3. Experts think the_________________is an important survival skill.

 4. It means they can surface to________________when they need to.

 

 

 

 

KEY

 

responses: reactions to something

echoes: when sound reflects off something and you hear it again

mammals: animals that produce milk to feed their babies

survival: when someone or something continues to live or exist, especially after a difficult or dangerous situation

surface: rise to the top of a body of water

predators: animals that kill and eats other animals

 

 True or false?

 

1. True

2. False

3. False

4. True

5. False

6. Truee

7. False

8. True

 

 What's the missing word?

 

1. tested

2. managed

3. ability

4. breathe