The Freyellidae are a

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

of deep-sea-dwelling

starfish Starfish or sea stars are Star polygon, star-shaped echinoderms belonging to the class (biology), class Asteroidea (). Common usage frequently finds these names being also applied to brittle star, ophiuroids, which are correctly referred to ...

. It is one of two families in the

order Order, ORDER or Orders may refer to: * A socio-political or established or existing order, e.g. World order, Ancien Regime, Pax Britannica * Categorization, the process in which ideas and objects are recognized, differentiated, and understood ...

Brisingida The Brisingids are deep-sea-dwelling starfish in the order Brisingida. Description These starfish have between 6 and 16 long, attenuated arms which they use for suspension feeding. Other characteristics include a single series of marginals, a ...

. The majority of

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

in this family are found in Antarctic waters and near

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. Other species have been found near

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

and the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

Taxonomy

The starfish '' Brisinga endecacnemos'' was discovered in deep water off Norway in 1856, followed by another

abyssal The abyssal zone or abyssopelagic zone is a layer of the pelagic zone of the ocean. The word ''abyss'' comes from the Greek word (), meaning "bottomless". At depths of , this zone remains in perpetual darkness. It covers 83% of the total area o ...

species, ''Brisinga coronata'', now '' Hymenodiscus coronata''. A new order,

, was erected to accommodate these, consisting of a single family,

Brisingidae The Brisingidae are a family of starfish found only in the deep sea. They inhabit both the Atlantic and Pacific Oceans at abyssal depths, and also occur in the Southern Ocean and around Antarctica at slightly shallower depths. The family was n ...

. Since then dozens of new species have been described from deep water

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

s and in 1986, the American zoologist

Maureen Downey Maureen Elizabeth Downey (May 1, 1921 – May 14, 2000) was an American zoologist who worked for three decades at the Smithsonian National Museum of Natural History. Known as "The Starfish Lady," she was an authority on sea stars and other echinod ...

split the family on morphological and behavioural grounds, creating the new family Freyellidae.

Characteristics

Members of this family have a small,

Ophiurida The Ophiurida are an order of echinoderms within the class Ophiuroidea. It includes the vast majority of living brittle stars. Characteristics Ophiurida have bursae for respiration and excretion, and dorsal and ventral arm shields are present an ...

-like disc, clearly demarcated from the arms, which number more than five. The disc is approximately circular with a rim of fused plates which gives rigidity. The

madreporite The madreporite is a light colored calcareous opening used to filter water into the water vascular system of echinoderms. It acts like a pressure-equalizing valve. It is visible as a small red or yellow button-like structure, looking like a sma ...

is near the margin of the disc. The arms are long and tapering with the ratio of the arm length to the disc radius being greater than 6/1. There is an acute angle between the arms . After a narrow cylindrical portion, the part of the arms closest to the disc accommodates the

gonad A gonad, sex gland, or reproductive gland is a Heterocrine gland, mixed gland and sex organ that produces the gametes and sex hormones of an organism. Female reproductive cells are egg cells, and male reproductive cells are sperm. The male gon ...

al tissues and widens out somewhat. Beyond this area, the arms taper to a long point. In all these aspects members of this family resemble members of

, the other family in the order

. They differ from Brisingidae in having the interradial arcs curved, having smaller madreporites, having bare interadial plates on the disc, having the aboral (upper) surface of the arms continuous with the disc, and having the plates on the

proximal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

parts of the arms abutting rather than overlapping each other.

Biology

Members of Freyellidae are usually found on soft substrates at depths between . This is a greater depth than Brisingidae, which occurs between , usually on hard surfaces. Because of the way their plates abut on the proximal ends of their arms, Freyellids have not been observed to raise their arms vertically above their discs, as do Brisingidae, and some are probably not

suspension feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a spec ...

s. Some do however raise the

distal Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position provi ...

portions of their arms, the parts beyond the gonadal regions.

Genera and species

The World Asteroida Database lists the following genera and species: *Family Freyellidae ** Genus '' Astrocles'' Fisher, 1917 — three species *** '' Astrocles actinodetus'' *** '' Astrocles djakonovi'' *** '' Astrocles japonicus'' ** Genus '' Belgicella'' Ludwig, 1903 —

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

*** '' Belgicella racovitzana'' ** Genus '' Colpaster'' Sladen, 1889 — two species *** '' Colpaster edwardsii'' *** '' Colpaster scutigerula'' ** Genus '' Freyastera'' Downey, 1986 — six species *** '' Freyastera benthophila'' *** '' Freyastera digitata'' *** '' Freyastera mexicana'' *** '' Freyastera mortenseni'' *** '' Freyastera sexradiata'' *** '' Freyastera tuberculata'' ** Genus ''

Freyella ''Freyella'' is a genus of deep-sea-dwelling starfish in the order Brisingida. Species There are currently 29 recognized species A species () is often defined as the largest group of organisms in which any two individuals of the appropriat ...

'' Perrier, 1885 (synonym: ''Freyellidea'', Fisher, 1917) — 29 species *** '' Freyella attenuata'' Sladen, 1889 *** '' Freyella breviispina'' (H.L. Clark, 1920) *** '' Freyella dimorpha'' Sladen, 1889 *** '' Freyella drygalskii'' (Döderlein, 1928) *** '' Freyella echinata'' Sladen, 1889 *** ''

Freyella elegans ''Freyella elegans'' is a species of deep-water starfish in the Family (biology), family Freyellidae in the Order (biology), order Brisingida, living at abyssal depths in the northwestern Atlantic Ocean. Taxonomy All ''Freyella'' species occur i ...

'' (Verrill, 1884) *** '' Freyella felleyra'' McKnight, 2006 *** '' Freyella flabellispina'' Korovchinsky & Galkin, 1984 *** '' Freyella formosa'' Korovchinsky, 1976 *** ''

Freyella fragilissima ''Freyella'' is a genus of deep-sea-dwelling starfish in the Order (biology), order Brisingida. Species There are currently 29 recognized species in this genus: - *''Freyella attenuata'' Sladen, 1889 *''Freyella breviispina'' (H.L. Clark, 1920) ...

'' Sladen, 1889 *** '' Freyella giardi'' Koehler, 1907 *** '' Freyella heroina'' Sladen, 1889 *** '' Freyella hexactis'' Baranova, 1957 *** '' Freyella indica'' Koehler, 1909 *** '' Freyella insignis'' Ludwig, 1905 *** '' Freyella kurilokamchatica'' Korovchinsky, 1976 *** '' Freyella loricata'' Korovchinsky & Galkin, 1984 *** '' Freyella macropedicellaria'' Korovchinsky & Galkin, 1984 *** '' Freyella microplax'' (Fisher, 1917) *** '' Freyella microspina'' Verrill, 1894 *** '' Freyella mutabila'' Korovchinsky, 1976 *** '' Freyella octoradiata'' (H.L. Clark, 1920) *** '' Freyella oligobrachia'' (H.L. Clark, 1920) *** '' Freyella pacifica'' Ludwig, 1905 *** '' Freyella pennata'' Sladen, 1889 *** '' Freyella propinqua'' Ludwig, 1905 *** '' Freyella recta'' Koehler, 1907 *** '' Freyella remex'' Sladen, 1889 *** '' Freyella vitjazi'' Korovchinsky & Galkin, 1984 ** Genus '' Freyellaster'' Fisher 1918 — five species *** '' Freyellaster fecundus'' *** '' Freyellaster intermedius'' *** '' Freyellaster polycnema'' *** '' Freyellaster scalaris'' *** '' Freyellaster spatulifer''

References

Other sources

* Clark, A.M. and Mah, C. (2001). An index of names of recent Asteroidea, part 4. Forcipulatida and Brisingida, in: Jangoux, M.; Lawrence, J.M. (Ed.) (2001). Echinoderm Studies, 6: pp. 229–347 * Mah, C.; Hansson, H. (2013). Freyella Perrier, 1885. In: Mah, C.L. (2013) World Asteroidea database. Accessed through
''Freyella'' Perrier, 1885
at the World Register of Marine Species on 2013-11-25 {{Taxonbar, from=Q3461434 Brisingida Echinoderm families