Mytilida is an order of marine

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, biv ...

molluscs, commonly known as true mussels. There is one extant superfamily, the Mytiloidea, with a single extant family, the

Mytilidae Mytilidae are a family of small to large marine and brackish-water bivalve molluscs in the order Mytilida. One of the genera, '' Limnoperna'', even inhabits freshwater environments. The order has only this one family which contains some 52 ge ...

. Species in the order Mytilida are found worldwide, but they are more abundant in colder seas, where they often form uninterrupted beds on rocky shores in the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species ...

and the shallow subtidal. The subfamily Bathymodiolinae is found in

deep-sea The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 metres (656 feet) or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combin ...

habitats. Mytilids include the well-known edible sea mussels. A common feature of the shells of mussels is an asymmetrical shell which has a thick, adherent

periostracum The periostracum ( ) is a thin, organic coating (or "skin") that is the outermost layer of the shell of many shelled animals, including molluscs and brachiopods. Among molluscs, it is primarily seen in snails and clams, i.e. in gastropods a ...

. The animals attach themselves to a solid substrate using a

byssus A byssus () is a bundle of filaments secreted by many species of bivalve mollusc that function to attach the mollusc to a solid surface. Species from several families of clams have a byssus, including pen shells ( Pinnidae), true mussels (Mytili ...

2010 taxonomy

In 2010, a new proposed classification system for the Bivalvia was published by Bieler, Carter & Coan. This included the suborder Mytiloida.Bieler, R., Carter, J.G. & Coan, E.V. (2010) ''Classification of Bivalve families''. Pp. 113-133, in: Bouchet, P. & Rocroi, J.P. (2010), ''Nomenclator of Bivalve Families. Malacologia'' 52(2): 1-184 *Superfamily † Modiolopsoidea **Family † Colpomyidae **Family † Modiolopsidae **Family † Saffordiidae *Superfamily Mytiloidea **Family † Mysideiellidae **Family

References

Bivalve orders {{bivalve-stub