It has rows of hair on its anterior legs, which it uses to filter food from the water.

[2] It naturally occurs in Europe, but was introduced to harbours of Australia by travelling in the ballast water of ships.

C. insidiosum occurs on American and European coasts from southern Baltic to eastern Mediterranean of North and South, and around Japan, and may grow up to 5 mm long.

[4] Monocorophium sextonae is 5 mm long and builds tubes of mud on algae, from shallow water up to 50 m deep.

In the late 1970 it was introduced to Ireland, possibly by natural means from Devon.