''Cnemidocarpa finmarkiensis'' 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 solitary

ascidian Ascidiacea, commonly known as the ascidians, tunicates (in part), and sea squirts (in part), is a polyphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer "tunic ...

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 ...

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 ...

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 ...

. Common names include broad base sea squirt, orange sea squirt, red sea squirt, shiny orange sea squirt, shiny red tunicate and Finmark's tunicate. It is native to shallow waters in the northern and northeastern Pacific Ocean.

Description

This is a solitary tunicate, which has no stalk, but adheres to the

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (locomotion), the surface over which an organism lo ...

with a broad base and often appears hemispherical. The two siphons are far apart and conspicuous when expanded, but much smaller when contracted, resembling small crosses. The length of this tunicate is seldom larger than , but can exceptionally reach , with a width of . The

tunic A tunic is a garment for the body, usually simple in style, reaching from the shoulders to a length somewhere between the hips and the knees. The name derives from the Latin ''tunica'', the basic garment worn by both men and women in Ancient Rom ...

is thin, but strong, being smooth and shiny. It is often pearly or opaque in appearance, bright red or pinkish-red, but small individuals are often white. The tunic has a 12.4% organic content, more than half of which is

cellulose Cellulose is an organic compound with the formula , a polysaccharide consisting of a linear chain of several hundred to many thousands of β(1→4) linked D-glucose units. Cellulose is an important structural component of the primary cell wall ...

(tunicin), the rest being protein.

Distribution

This tunicate is a coldwater species and occurs in the northern and northeastern Pacific Ocean. It is circum-boreal in the Arctic and its range in the

Pacific Northwest The Pacific Northwest (sometimes Cascadia, or simply abbreviated as PNW) is a geographic region in western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though ...

extends from

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S ...

Point Conception Point Conception ( Chumash: ''Humqaq'') is a headland along the Gaviota Coast in southwestern Santa Barbara County, California. It is the point where the Santa Barbara Channel meets the Pacific Ocean, and as the corner between the mostly north- ...

in California. Its depth range extends from the low subtidal to at least , but it occurs down to about in Japan.

Ecology

Like other tunicates, ''Cnemidocarpa finmarkiensis'' is a

suspension 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 is drawn into the body through the buccal siphon by the action of cilia lining the gill slits, the food particles are extracted and the water is expelled through the atrial siphon. It is a

hermaphrodite In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many taxonomic groups of animals (mostly invertebrates) do not have ...

, with breeding taking place in summer, fertilisation being external. A symbiotic

copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat. Some species are planktonic (inhabiting sea waters), some are benthic (living on the ocean floor), a number of species have p ...

often lives inside the atrium and various invertebrates shelter around the tunicate's base. A

predator Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

of this tunicate is the rainbow star (''

Orthasterias koehleri ''Orthasterias'' is a genus of sea stars in the family Asteriidae. ''Orthasterias koehleri'', the rainbow star or red-banded sea star, is the only species in the genus. It is found in the North Pacific Ocean. Description The rainbow star is a ...

'').

References

{{Taxonbar, from=Q4912058 Stolidobranchia Fauna of the Arctic Ocean Fauna of the Pacific Ocean Animals described in 1893