Behaviour

Pseudoplanktonic sessile, filter feeder that lived attached to a floating tree trunk.

Seirocrinus subangularis is a primarily fixed animal, with the fan like crown supported by a tether like stem.

The arms are arranged in a parabolic fan that faces into the prevailing water current. Each of the arms have numerous rows of featherlike pinnules, which are covered in podia. The podia are shaped like small tenticles and bear long slender mucus secreting papillae.

During feeding, food becomes trapped in the mucus and is tossed into the food groove by a sudden whip-like action, which in-turn are transported along the food groove to the mouth at the centre of the fan.

Seirocrinus subangularis is attached to the sea floor by an attachment disk.

Migration

As Seirocrinus subangularis was attached to its wood raft structure through-out life (Seilacher et al 1968: Simms 1986) its movement and food supply was dependent on the current flow as the log is dragged through the water.

Seirocrinus subangularis is sessile so is limited to bending movements of the stalk and flexion and extension of the arms.

Associations

These crinoids only occur attached to floating logs. The logs also have cementing bivalves at the surface.