Mussel

Mussel is the <a href="/facts/Common_name/3KNNezEU">common name</a> used for members of several families of <a href="/facts/Bivalve/IQDxHVc8">bivalve</a> <a href="/facts/Mollusc/1elgknsQ">molluscs</a>, from saltwater and <a href="/facts/Freshwater_bivalve/8AR6JaGt">freshwater</a> habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.
The word "mussel" is frequently used to mean the bivalves of the marine family <a href="/facts/Mytilidae/VegW6cCg">Mytilidae</a>, most of which live on exposed shores in the intertidal zone, attached by means of their strong <a href="/facts/Byssus/7heAVVFr">byssal threads</a> ("beard") to a firm substrate. A few species (in the genus <a href="/facts/Bathymodiolus/JaKAlV4b">Bathymodiolus</a>) have colonised <a href="/facts/Hydrothermal_vent/0xPqNUkY">hydrothermal vents</a> associated with deep ocean ridges.
In most marine mussels the shell is longer than it is wide, being wedge-shaped or asymmetrical. The external colour of the shell is often dark blue, blackish, or brown, while the interior is silvery and somewhat <a href="/facts/Nacre/a5ek6xm4">nacreous</a>.
The common name "mussel" is also used for many freshwater bivalves, including the <a href="/facts/Freshwater_pearl_mussel/3GFoxjDa">freshwater pearl mussels</a>. Freshwater mussel species inhabit lakes, ponds, rivers, creeks, canals, and they are classified in a different <a href="/facts/Subclass_(biology)/a7MrgFu3">subclass</a> of bivalves, despite some very superficial similarities in appearance.
Freshwater <a href="/facts/Zebra_mussels/4wTbAMSV">zebra mussels</a> and their relatives in the family <a href="/facts/Dreissenidae/z13Uf01E">Dreissenidae</a> are not related to previously mentioned groups, even though they resemble many Mytilus species in shape, and live attached to rocks and other hard surfaces in a similar manner, using a byssus. They are classified with the <a href="/facts/Heterodonta/aq3PP5T3">Heterodonta</a>, the taxonomic group which includes most of the bivalves commonly referred to as "clams".

Mussel open-in-new

Mussel