They are called sand hoppers, beach hoppers and amphipods. Other species in this group live in freshwater, soil and under rotting logs. These tiny animals have rounded bodies flattened on the sides. They have many legs and large antennae. They get their name because they leap around when they are disturbed.
On a beach they are most commonly found under mats of rotting seaweed. When the seaweed is turned over, the sand hoppers try to escape by leaping in different directions. They also live in most other marine environments. Some are black and others can have bright colourful patterns. Most species eat decaying material.