Talitrus saltator, a species of sand hopper, is a common amphipod crustacean of sandy coasts around Europe. The animal's typical "hopping" movement gives it its common name, and is produced by a flexion of the abdomen. In order to do this, it must stand on its legs and suddenly extend its abdomen from under its body. It can thus leap several inches into the air, although without any control over its direction. A great deal of scientific research has been carried out on the animal, to determine the environmental cues which it uses to control its behavior.

Talitridae is a family of amphipods. Terrestrial species are often referred to as landhoppers and beach dwellers are called sandhoppers or sand fleas. The name sand flea is misleading, though, because these talitrid amphipods are not siphonapterans, do not bite people, and are not limited to sandy beaches.