The Euryalida are an order of
brittle star
Brittle stars, serpent stars, or ophiuroids (; ; referring to the serpent-like arms of the brittle star) are echinoderms in the class Ophiuroidea, closely related to starfish. They crawl across the sea floor using their flexible arms for locomot ...
s,
which includes large species with either branching arms (called "basket stars") or long and curling arms (called "snake stars").
Characteristics
Many of the species in this order have characteristic repeatedly branched arms (a shape known as "basket stars", which includes most
Gorgonocephalidae and two species in the family
Euryalidae), while the other species have very long and curling arms, and go rather by the name of "snake stars" (mostly abyssal species). Many of them live in
deep sea
The deep sea is broadly defined as the ocean depth where light begins to fade, at an approximate depth of 200 metres (656 feet) or the point of transition from continental shelves to continental slopes. Conditions within the deep sea are a combin ...
habitats or cold waters, though some basket stars can be seen at night in shallow tropical reefs. Most young basket stars live on specific type of coral. In the wild they may live up to 35 years. They weigh up to Like other
echinoderm
An echinoderm () is any member of the phylum Echinodermata (). The adults are recognisable by their (usually five-point) radial symmetry, and include starfish, brittle stars, sea urchins, sand dollars, and sea cucumbers, as well as the s ...
s, basket stars lack blood and achieve gas exchange via their water vascular system.
The basket stars are the largest ophiuroids with ''
Gorgonocephalus stimpsoni'' measuring up to 70 cm in arm length with a disk diameter of 14 cm.
Systematics and phylogeny
The fossil record of this group is rather poor and only dates back to
Carboniferous.
Basket stars are divided into the following families:
* family
Asteronychidae
Asteronychidae is a family of echinoderms belonging to the order Euryalida.
Genera:
* ''Asteronyx'' Müller & Troschel, 1842
* ''Astrodia'' Verrill, 1899
* ''Astronebris'' Downey, 1967
* ''Lillithaster'' Thuy, Numberger-Thuy & Jagt, 2018
* ''Ophi ...
Ljungman, 1867 -- 4 genera (11 species)
* family
Euryalidae Gray, 1840, emended Okanishi et al., 2011 -- 11 genera (89 species)
* family
Gorgonocephalidae Ljungman, 1867 -- 34 genera (96 species)
** sub-family
Astrocloninae Okanishi & Fujita, 2018
** sub-family
Astrothamninae Okanishi & Fujita, 2013
** sub-family
Astrotominae Matsumoto, 1915
** sub-family
Gorgonocephalinae Döderlein, 1911
Image:Astrodia tenuispina (MIIC-01651).jpg, '' Astrodia tenuispina'' (Asteronychidae
Asteronychidae is a family of echinoderms belonging to the order Euryalida.
Genera:
* ''Asteronyx'' Müller & Troschel, 1842
* ''Astrodia'' Verrill, 1899
* ''Astronebris'' Downey, 1967
* ''Lillithaster'' Thuy, Numberger-Thuy & Jagt, 2018
* ''Ophi ...
)
Image:Astroceras aurantiacum.jpg, '' Astroceras aurantiacum'' ( Euryalidae)
Image:Basket star on sea fan at Fan Reef DSC08990.JPG, ''Astrocladus euryale
Astrocladus euryale, the basket star, or gorgon's head is a brittlestar of the family Gorgonocephalidae found in the coastal waters of South Africa from the west coast of the Cape Peninsula to about Algoa Bay.
Description
The 10 arms branch repe ...
'' ( Gorgonocephalidae)
Image:Squamophis lifouensis.jpg, '' Squamophis lifouensis'' ( Euryalidae, ex- Astrocharidae)
Gallery
File:Basket Star in the Atlantic Ocean at 28m near Maori Bay.jpg, A basket star, located in an area known as "Star Wall", near Maori Bay, New Zealand at a depth of approximately 28 m.
File:Close-up of basket star arm fragment in the Red Sea.JPG, Close-up of '' Astroboa nuda'' basket star arm
File:BasketStar NOAA.jpg, Basket star taken from the Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe ...
Image:Asteroschematidae Hawaii 01.jpg, An abyssal snake star curled around a cold-water coral.
Image:Euryale aspera (MIIC-01520).jpg, Beware of the genus ''Euryale
In Greek mythology, Euryale ( ; grc, Εὐρυάλη, lit=far-roaming") was the name of the following characters:
* Euryale (Gorgon), Euryale, one of the Gorgons.
* Euryale, daughter of Minos, possible mother of the great hunter Orion (mythology) ...
'', the only "basket star" not belonging to the Gorgonocephalidae (family Euryalidae).
References
External links
*
Ophiuroidea
Phrynophiurida
{{Ophiuroidea-stub