''Stolonica socialis'' is a

species In biology, a species is the basic unit of 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 the appropriate s ...

tunicate A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ca ...

or sea squirt in the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Styelidae Styelidae is a family of ascidian tunicates.Lambert, G.; Gittenberger, A.; Sanamyan, K. (2015)Styelidae Sluiter, 1895.In: Shenkar, N.; Gittenberger, A.; Lambert, G.; Rius, M.; Moreira Da Rocha, R.; Swalla, B.J.; Turon, X. (2015) Ascidiacea World ...

, commonly known as orange sea grapes. It is native to the northeastern Atlantic Ocean, where it lives on the rocky seabed in shallow water.Sanamyan, K. (2015)
''Stolonica socialis'' Hartmeyer, 1903.
In: Shenkar, N.; Gittenberger, A.; Lambert, G.; Rius, M.; Moreira Da Rocha, R.; Swalla, B.J.; Turon, X. (2015) Ascidiacea World Database. Accessed through: World Register of Marine Species on 2015-12-23

Description

''Stolonica socialis'' is a colonial tunicate forming small clusters of

zooid A zooid or zoöid is a single animal that is part of a colonial animal. This lifestyle has been adopted by animals from separate unrelated taxa. Zooids are multicellular; their structure is similar to that of other solitary animals. The zooi ...

s, joined at the base by a mat of

stolon In biology, stolons (from Latin '' stolō'', genitive ''stolōnis'' – "branch"), also known as runners, are horizontal connections between organisms. They may be part of the organism, or of its skeleton; typically, animal stolons are external s ...

s. Each zooid is up to high, rectangular or ovoid. Both of the small

siphon A siphon (from grc, σίφων, síphōn, "pipe, tube", also spelled nonetymologically syphon) is any of a wide variety of devices that involve the flow of liquids through tubes. In a narrower sense, the word refers particularly to a tube in a ...

s on each zooid are situated near the apex. The outer surface of each zooids is smooth and sand does not adhere to it, although sand does adhere to the mat of stolons. Although most colonies are orange, some are yellow and others pale brown. The colonies spread across the rocks and can form large sheets. In winter, orange-red buds develop on the stolons. Similar species with which it could be confused include '' Dendrodoa grossularia'' and ''

Distomus variolosus ''Distomus variolosus'' is a species of tunicate or sea squirt in the family Styelidae. It is native to the northeastern Atlantic Ocean where it lives on the seabed,Gittenberger, A.; Sanamyan, K. (2015)''Distomus variolosus'' Gaertner, 1774.In: S ...

'', but both of these are red.

Distribution

''Stolonica socialis'' is found in the northeastern Atlantic Ocean, the

Irish Sea The Irish Sea or , gv, Y Keayn Yernagh, sco, Erse Sie, gd, Muir Èireann , Ulster-Scots: ''Airish Sea'', cy, Môr Iwerddon . is an extensive body of water that separates the islands of Ireland and Great Britain. It is linked to the Ce ...

and the

English Channel The English Channel, "The Sleeve"; nrf, la Maunche, "The Sleeve" (Cotentinais) or ( Jèrriais), (Guernésiais), "The Channel"; br, Mor Breizh, "Sea of Brittany"; cy, Môr Udd, "Lord's Sea"; kw, Mor Bretannek, "British Sea"; nl, Het Kana ...

. Its range includes the coasts of northwestern Ireland and southeastern Ireland, Wales, southwestern England and northwestern France. It grows on rocks, including those swept by strong currents, at depths from or more. It favours shaded rocks, boulders and overhangs, and can form large populations. At exceptionally low tides, it may be found under overhanging rocks on the foreshore.

Biology

Like other tunicates, ''Stolonica socialis'' is a

filter feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

, water being sucked into the hollow body of each zooid via an inhalent siphon, large particles being rejected by tentacles at the siphon entrance. Edible particles are sieved out of the water stream, and the water is then pumped out through the exhalent siphon. The colony grows by the stolons extending across the rock surface and budding new zooids at intervals, with large patches of zooids often being formed. In winter these buds may remain dormant as small spherical outgrowths, and with the arrival of warmer weather in the spring, growth can restart and the spherules can develop into zooids. In adverse conditions, sexual reproduction takes place, with eggs and sperm being liberated into the

water column A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...

. The tissues of this tunicate contain stolonoxides, secondary metabolites that have been found to have

cytotoxic Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are an immune cell or some types of venom, e.g. from the puff adder (''Bitis arietans'') or brown recluse spider (''Loxosceles reclusa''). Cell physiology Treating cells ...

effects; this may be the reason that the tunics remain largely clear of epibionts whereas many other tunicates are heavily colonised by other organisms.

References

{{Taxonbar, from=Q4918555 Stolidobranchia Fauna of the Atlantic Ocean Animals described in 1903