Wild Harris

Sea Pens

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There are 3 species of sea pen in Harris sealochs.

Each sea pen is a colony of polyps (anemone- like animals) arranged like a feather on a flexible support which is rooted in the mud. The polyps catch passing food with their tentacles in much the same way as anemones and corals do. The common sea pen looks a bit like a bottle brush, and occurs in large numbers on areas of flat fine sand or mud. The animals are spaced about a foot apart, somewhat resembling a small forest of white trees. The phosphorescent sea pen is larger, and looks like a big feather. It glows in the dark if disturbed, which is how it gets its name. A third, taller sea pen lives in deep dark water such as the sea bed of Loch Seaforth. All these sea pens are easily damaged or destroyed by fishing gear, and once knocked over they are unable to right themselves. Pollution from salmon farms is also detrimental to their health; sea pens cannot survive under or close to sea cages.

common sea pen.jpgCommon Sea Pen    (Photo: Sue Scott)

Looking a bit like a bottle brush, the common seapen's polyps show up as white spots on the ends of the branches.

sea pens common.jpgCommon Sea Pen Colony    (Photo: Sue Scott)

A typical 'forest' of sea pens on a the ends of the branches. muddy sea floor

phosphor sea pen.jpgPhosphor Sea Pen    (Photo: Sue Scott)

This feather-like animal is a phosphorescent sea pen. When disturbed it will light up!

deep seapen.jpgDeep Sea Pens    (Photo: Sue Scott)

This sea pen is only found in deep water, where it grows to a height of a metre or more.

by Paul Tyler

Link to Shore Animals

Link to Soft Seabed Animals