''Mycale adhaerens'', the purple scallop sponge, is a

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

of marine

demosponge Demosponges (Demospongiae) are the most diverse class in the phylum Porifera. They include 76.2% of all species of sponges with nearly 8,800 species worldwide (World Porifera Database). They are sponges with a soft body that covers a hard ...

in 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 to maintain the well-being of its members and of society. Idea ...

Mycalidae Mycalidae is a Family (biology), family of marine demosponges. Genera According to the World Register of Marine Species, there are only two Genus, genera in this family. Previously there were about 26, but most of these have been reallocated as ...

. ''Mycale'' is a large genus and this species is placed in the subgenus ''Aegogropila'' making its full name, ''Mycale'' (''Aegogropila'') ''adhaerens''. It grows

symbiotically Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or para ...

on the valves of

scallop Scallop () is a common name that encompasses various species of marine bivalve mollusks in the taxonomic family Pectinidae, the scallops. However, the common name "scallop" is also sometimes applied to species in other closely related familie ...

shells and is native to the west coast of North America.

Description

''Mycale adhaerens'' forms a thin encrusting layer on the valves of living scallop shells such as ''

Chlamys hastata ''Chlamys hastata'', the spear scallop, spiny scallop or swimming scallop, is a species of bivalve mollusc in the family Pectinidae found on the west coast of North America from the Gulf of Alaska to San Diego, California. A limited number of th ...

'' and ''

Chlamys rubida ''Chlamys rubida''Also known as the Pacific pink scallop, pink scallop, scooter scallop (for its tendency to "scoot" along the sea floor, and the singing scallop (for the noise it sometimes makes while swimming is a species of bivalve mollusc in ...

''. It ranges in colour from yellowish-brown through purple to pink. The only other species of sponge growing on the Pacific Coast with which it might be confused is ''

Myxilla incrustans ''Myxilla incrustans'' is a species of demosponge. It is an encrusting species and is usually yellow. Description ''M. incrustans'' is an encrusting sponge occurring in patches up to across and high. It is usually some shade of yellow but can ...

''; that species is usually some shade of brown, has a finer, less fibrous structure and has larger

oscula ''Oscula'' is a genus of shield bugs belonging to the family Plataspidae Plataspidae (Emendation (taxonomy), emended by some later authors as "Plataspididae", in violation of International Code of Zoological Nomenclature, ICZN Code Article 29.5 ...

Ecology

The relationship between the sponge and the scallop on which it lives is mutualistic, each receiving benefits. The scallop is often preyed on by the starfish '' Evasterias troscheli'' but when the starfish touches the sponge it tends to move away, either being repelled by some secretion from the sponge or by the

spicules Spicules are any of various small needle-like anatomical structures occurring in organisms Spicule may also refer to: * Spicule (sponge), small skeletal elements of sea sponges * Spicule (nematode), reproductive structures found in male nematodes ...

present in the sponge's tissue. If the starfish does try to force the scallop's valves apart, the

tube feet Tube feet (technically podia) are small active tubular projections on the oral face of an echinoderm, whether the arms of a starfish, or the undersides of sea urchins, sand dollars and sea cucumbers; they are more discreet though present on bri ...

seem unable to obtain a purchase on the sponge. Quite apart from this, the scallop will often try to escape from the starfish by swimming away, and will also try to evade the

nudibranch Nudibranchs () are a group of soft-bodied marine gastropod molluscs which shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have been given colourful nicknames to mat ...

s ''

Doris odhneri ''Doris odhneri'' is a species of sea slug, a dorid nudibranch, a shell-less marine gastropod mollusk in the family Dorididae.Behrens D. W. (2004). "Pacific Coast Nudibranchs, Supplement 2. New species to the Pacific Coast and new information on ...

'' and ''

Peltodoris nobilis ''Peltodoris nobilis'', commonly called the sea lemon, false sea lemon, or the noble dorid, is a species of colorful sea slug, a dorid nudibranch, a shell-less marine gastropod mollusk in the family Discodorididae.Gofas, S.; Rosenberg, G. (201 ...

'' which feed on the sponge. The presence of the sponge also seems to deter the octopuses ''

Enteroctopus dofleini The giant Pacific octopus (''Enteroctopus dofleini''), also known as the North Pacific giant octopus, is a large marine cephalopod belonging to the genus ''Enteroctopus''. Its spatial distribution includes the coastal North Pacific, along Mexico ...

'' and '' Octopus rubescens'' from feeding on the scallop. The sponge may also benefit from the scallop's movements, both by being transported into areas of clean water and by avoiding the accumulation of sediment. A number of bioactive metabolites have been isolated from the sponge, some with cytotoxic activity. In Hong Kong, ''

Pseudoalteromonas spongiae ''Pseudoalteromonas spongiae'' is a marine bacterium isolated from the sponge ''Mycale adhaerens ''Mycale adhaerens'', the purple scallop sponge, is a species of marine demosponge in the family Mycalidae. ''Mycale'' is a large genus and this s ...

'', a marine

bacterium Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were a ...

, has been isolated from the surface of the sponge. The significance of this association is unknown.

References

{{Taxonbar, from=Q2508148 Poecilosclerida Animals described in 1893 Taxa named by Lawrence Lambe