A to Z of Invasive Marine Species

S. muticum was first found attached in Bembridge, Isle of Wight, in 1971 where it most likely had arrived from France.

As it was so recently introduced, we have a full chronology of its spread and there have been plenty of studies on the seaweed so a lot is known.

It is not known how either of these species were introduced in the UK. The main hypotheses for this are the same as most other species on the list; ballast transport or introduced by imported oysters.

They are marine filter feeders with a sac-like body structure. In their respiration and feeding they take in water through an inhalant siphon and expel the filtered water through an exhalant siphon.

The dwarf crab is native to the east coast of the Americas where it has the distribution from New Brunswick, Canada to north-east Brazil. There is also a breeding fresh water population in the Brazos River basin, Texas.

It is most common off the coast of Essex and in the Thames estuary (River Medway). There are also isolated populations in both North Wales and Cornwall.

Cells are found either in isolation or in colony where they are organized in straight lines or in a zigzag pattern in the pelagic zone or sometimes attached to other marine species.

It still regarded as a potentially important commercial species but it is highly susceptible to a disease (Bonamiosis) caused by Bonamia sp.

This clam has many common names including steamers, softshells, longnecks. It is a species of edible saltwater clam, a marine bivalve mollusk in the family Myidae which originates in the mud flats of America.