Phosphorescent Sea Pen

• GeneralA feather-shaped colony rooted in the mud, which gives off flashes of light.
• It can withdraw entirely into the sediment when disturbed, vanishing from the seabed in seconds.
• Its beds form soft-bottom habitats that are protected in Europe and highly vulnerable to bottom trawling.
• It is not one animal but a colony: an elongated primary polyp from which side branches bearing the feeding polyps grow, hence its quill-pen shape.
• It is intensely bioluminescent, as its name indicates. Touched, it gives off waves of blue-green light that travel up the colony, passing from polyp to polyp.
• It can withdraw completely into the mud if disturbed, and emerge again afterwards.
• Its sea pen fields form a soft-bottom habitat protected under European legislation, and one that bottom trawling destroys easily.

Skeleton type

Invertebrate - internal calcareous axis and sclerites (octocoral)

Habitat and environment

Muddy bottoms from 20 to 400 m

Sources consulted: Linneo (1758) · Marine Life Information Network · Joint Nature Conservation Committee · Anatomia de Anthozoa · NCBI PMC12113132 (octocorales y Pennatulacea)