Tube-dwelling Anemone

This Cerianthid sea anemone is a nocturnal species which immediately curls up and retreats when dive lights hit it.
Cerianthids look very similar to sea anemones, but belong to an entirely different subclass of anthozoans. Tube anemones live and can withdraw into tubes, which are made of a fibrous material, which is made from secreted mucus and threads of nematocyst-like organelles, known as ptychocysts.

Cerianthids have a crown of tentacles that consists of two whorls of distinctly different sized tentacles. The outer whorl consists of large tentacles that extend outwards. These tentacles taper to points and are mostly used in food capture and defence. The smaller innner tentacles are held more erect than the larger lateral tentacles and are used for food manipulation and ingestion.