A Sea-Anemone from Brackish Water

Abstract

DURING the past century, a series of brackish lagoons was established by storm action along the east coast of England at Shinglestreet, near Ipswich. There are eight lagoons of varying sizes, one of which is now dry, along the two miles immediately south of the River Ore. Although only the most northerly opens into the sea, all except the southernmost lagoon are tidal to some extent. In this last one a small white sea-anemone occurs abundantly in the fine bottom mud: more than a hundred specimens were obtained during one visit in November. The anemone appears to be Nematostella vectensis, an Edwardsid described by Stephenson¹ and so far recorded only from the Isle of Wight. Among other features, it is characterized by the presence of nematosomes—small round bodies packed with nematocysts—which circulate freely in the cœlenteron or rest near the insertion of mesenteries in the body wall. They are seen in the accompanying photographs and form an unusual feature of considerable interest. Their origin is unknown.