''Montacuta substriata'' is a species of small 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, bival ...

mollusc Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is esti ...

in the family

Lasaeidae Lasaeidae is a family of very small saltwater clams, marine bivalve molluscs in the order Galeommatida. These bivalves are sometimes called "kelly clams", because one of the genera in this family is ''Kellia''. Genera and species Genera and s ...

. It is found on the eastern side of the Atlantic Ocean where it is often associated with a

sea urchin Sea urchins () are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin live on the seabed of every ocean and inhabit every depth zone from the intertidal seashore down to . The spherical, hard shells (tests) of ...

, such as ''

Spatangus purpureus ''Spatangus purpureus'', commonly known as the purple heart urchin, is a species of sea urchin in the family Spatangidae. It is found in the eastern Atlantic Ocean and the Mediterranean Sea, where it lives immersed in the sediment. Description ' ...

''. This species was first described in 1808 by the English naturalist George Montagu who gave it the name ''Ligula substriata''. It was later transferred to the genus '' Montacuta'', making it ''Montacuta substriata''.

Description

''Montacuta substriata'' is a very small oval bivalve, commonly about long, but sometimes up to twice that length. It has a smooth, pale yellow shell and attaches itself to one of the smaller spines on the oral surface (underside) of a sediment-dwelling sea urchin, such as ''

'' or an ''

Echinocardium ''Echinocardium'' is a genus of sea urchins of the family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is ...

'' species. It usually attaches near the anus, where it is difficult to distinguish from a coarse grain of sand.

Distribution and habitat

''Montacuta substriata'' is native to the coasts of Western Europe, its range extending from Norway to the Mediterranean Sea. It occurs on the sandy and gravelly seabed in areas where the burrowing urchins live.

Ecology

''Montacuta substriata'' has a commensal arrangement with its

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

. Both are likely

detritivore Detritivores (also known as detrivores, detritophages, detritus feeders, or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrates, ...

s, feeding on fragments of seaweed. The clam benefits from the flow of water past it caused by the sea urchin's burrowing activities. The male ''Montacuta substriata'' liberates gametes into the water column and the eggs are incubated for a while by the female. Veliger larvae are then liberated into the sea where they are planktonic for several months before settling on the seabed and undergoing

metamorphosis Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...

. The juveniles are mobile and have need to find a host. In their search, they are affected by water currents and attracted by a chemical signal from a potential sea urchin host; they show negative

geotaxis Gravitaxis (or ''geotaxis'') is a form of taxis characterized by the directional movement of an organism in response to gravity. Gravitaxis is one of the many forms of taxis. It is characterized by the movement of an organism in response to gravita ...

References

{{Taxonbar, from=Q3788508 Lasaeidae Molluscs of the Atlantic Ocean Molluscs of the Mediterranean Sea Taxa named by George Montagu (naturalist) Bivalves described in 1808