White-plumed Anemone

Metridium farcimen is a large sea anemone, occasionally reaching a height of one metre (39 in) when fully extended. More usually it is 50 cm (20 in) or less in height but is very variable in shape. It can retract its tentacles and form a ball up to 25 cm (10 in) in diameter. The column is slender, smooth and studded with acontia. These are openings through which thread-like nematocysts from inside the body wall can protrude. There are no tubercles and the column is topped by a parapet. The oral disc is lobed and deeply convoluted at the edge and bears well over 100 fine, short, tapering tentacles. The colour is generally opaque white, but orange, salmon and brown specimens sometimes occur.