Echolocation :)

Dolphins have their own special way of hunting for food. It’s called ‘Echolocation’. As it is so dark under water, dolphins can not use sight as one of their senses. This is where echolocation comes in handy. Echolocation is when a dolphin makes a sound, and then the sound reflects off an object. It gets sent back to the dolphin. Dolphins can detect how far away this object is.

Dolphins aren't the only mammals that use echolocation. Bats for instance, use echolocation as it is essential for them. Bats are nocturnal, which means they sleep through the day and come out at night to hunt for food. No animal can see in complete darkness.  Bats send out small signals to find their food.