Amphipods are small, shrimp-like invertebrates, and members of the sub-phylum Crustacea that includes crabs, lobsters and barnacles.

What is the difference between sea fleas and sea lice?

Sea fleas have been in the news recently. Common names often vary from area to area and what are known as “sea fleas” in Australia are called “sand hoppers” in the UK (e.g. the sand hopper Talitrus saltator see more at )

Sea fleas/sand hoppers are amphipod crustaceans. There are many species, mostly marine but also some that live in freshwater and some that are terrestrial. See our YouTube video for an introduction to amphipods.

We use the term “sea lice” for parasitic copepods, best known for being parasites of salmon (and a problem for salmon farms). However, in other countries sea lice is used for isopods, which we in the UK call “sea slaters”. Isopods are probably the group best known for biting swimmers and there was some suggestion in one of the media reports that they may have also been implicated in the Australian attack.

More about amphipods

Amphipods are common worldwide. They are detritivores (feed on detritus such as seaweed and sometimes dead animals) and serve a useful function by breaking down dead seaweed and the carcasses of animals. The ones in our YouTube video are a species called Gammarus marinus and were found under rocks on the upper shore around Plymouth. They are completely harmless.

Are amphipods dangerous?

It is very unlikely that amphipods will harm you. The type thought to be responsible for the 'attack' in Australia is a lysianassid amphipod. Media reports from the Melbourne incident suggest the victim may have been unfortunate enough to have encountered a feeding swarm and was standing still for a long time in cold water.

An amphipod of the suborder hyperiidae. Image: Dave Conway.

The isopod sea slater Ligia oceanica on rocks on the upper shore at night. Image: Jack Sewell.

Aug 10, 2017 By guba