Mussels

Mussels

Mussels are found everywhere, attached to any solid substrate. Mussels are to the sea what grass is to suburbia. Mussels lack the muscular foot of clams or the large hinge muscle of scallops. Instead, they have a "beard" of tough fibers near the hinge with which they attach themselves.

The Blue Mussel Mytilus edulis, to 4" is the edible mussel. The similar Horse Mussel Modiolus modiolus grows to 6", and is considered inedible. Both types are found from the intertidal zone down to the depths. See entry on barnacles.

Blue Mussel
Blue Mussel

The other common type of mussel in our area is the Ribbed Mussel Modiolus demisus, to 4". The Ribbed Mussel is roughly the same shape as the Blue Mussel, but has a ribbed shell instead of smooth. It is usually found in brackish water, in bays, estuaries, and marinas, and is inedible. Freshwater Zebra Mussels are more closely related to clams.


Hermit Crab

Hermit crabs live inside empty snail shells in shallow water along beaches and in estuaries, small specimens on mudflats and large ones offshore. Some hermit crabs are entirely terrestrial, needing the water only to lay eggs. In the South Pacific, there are types that actually climb trees and very large ones that don't bother with a shell as adults.

The size of the crab determines what kind of shell, and upgrades are required as the crab grows. The Flat-Clawed Hermit Crab Pagurus arcuatus (right) is the largest in our area, and will often use Moon Snails and Whelks, but you will only find the big ones in deeper water. Small ones use Periwinkles and Oyster Drills.