Blue Mussel, Mytilus edulis

The Blue Mussel, Mytilus edulis, is an edible marine bivalve mollusk of medium size belonging to the family Mytilidae. Blue mussels are subject to commercial use along with intense aquaculture.

These mussels are boreo-temperate invertebrates that reside in intertidal areas attached to rocks and other hard substrates by strong thread like structures called byssal threads that are secreted by byssal glands located in the foot of the mussel.

The shell shape is triangular and elongate with rounded edges. It is smooth with a sculpturing of fine concentric growth lines but no radiating ribs. The shells of this species are purple, blue, or sometimes brown in color, sometimes with radial stripes. The outer surface is covered by the periostracum which as eroded, exposes the color prismatic calcitic layer. Blue mussels are semi-sessile, having the ability to detach and reattach to a surface allowing the mollusk to reposition itself relative to the position of the water.

These mussels have separate sexes. Once the sperm and eggs are fully developed, they are released into the water column for fertilization. Although there are about 10,000 sperm per egg, large proportions of eggs deposited by blue mussel are never fertilized.

Image Caption: Blue Mussel. Credit: Rainer Zenz/Wikipedia (CC BY-SA 3.0)