A vocabulary of landscape — a landscape of words
1367 entries
sand dollar
A sand dollar is a flattened sea urchin that lives buried in sand, feeding on fine particles moved along its underside by thousands of tiny tube feet and spines. Living animals are covered in a velvet of short purple or brown spines and move slowly under the surface. The white disc found on a beach is the bare skeleton, marked with a five-petalled flower pattern that is a set of respiratory pores.
Etymology
The English name is for the shape and color of the bleached test, which does look like a large pale coin. The same object is a sea biscuit, a sand cake, and a pansy shell in other English-speaking places, and in several European languages it is a sea cake or a cake urchin, so the comparison to baked goods is nearly universal.
Notes
Sand dollar larvae do something almost nothing else does. Faced with chemical evidence of a predatory fish, a larva clones itself, splitting into two smaller individuals, on the argument that a smaller larva is harder for a fish to detect. The five-part symmetry of the adult, shared with all urchins and starfish, is built out of a larva that is bilaterally symmetrical like a fish.