Hurrah, we come to the end of the module! We started by asking how animals in water communicate. Especially deep inside water, there is very little light. So, animals cannot see each other.

This means that animals can only use sound to communicate with one another. As we saw, animals like whales and dolphins have much better hearing than us.

Also, because sound waves travel faster in water than in air, communicating using sounds is very effective for animals living in water.