Creature of the week
Sand dollar, or Sea biscuit or Snapper biscuit
Arachnoides zelandiae
Up to 100 mm
Sand dollar
Arachnoides zelandiae
up to100mm
Description:
Shape is circular and flattened, - lower surface flat while the
upper surface is a very shallow cone.
It belongs to the starfish (Echinoderm = spiny skin)
family. The under-surface and rim have thousands of tiny mobile
tube feet while the mouth is centrally placed beneath.
Habitat:
Mid to low tide on the sandy beach where it can dig in quite
rapidly just below the surface sand.
Here it can leave very “alien” signs when stationary, and wide rail-road tracks when on the move.
Diet:
It feeds on fine organic particles which, as the animal moves through the surface sand, fall between
the rows of tube feet and are carried by moving hairs (cilia) to the mouth.
Photos David Gray
@ MERC