Acrocnida brachiata

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Acrocnida brachiata
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Echinodermata
Class: Ophiuroidea
Order: Ophiurida
Family: Amphiuridae
Genus: Acrocnida
Species:
A. brachiata
Binomial name
Acrocnida brachiata
(Montagu, 1804) [1]
Synonyms [1]
  • Acrocnida neapolitana (M. Sars, 1857)
  • Amphiocnida brachiata (Montagu, 1804)
  • Amphiura brachiata (Montagu, 1804)
  • Amphiura neapolitana M. Sars, 1857)
  • Asterias brachiata Montagu, 1804)
  • Ophiocentrus brachiatus (Montagu, 1804)
  • Ophiocoma brachiata (Montagu, 1804)
  • Ophiura brachiata (Montagu, 1804)

Acrocnida brachiata, the sand burrowing brittlestar, is a species of brittle star in the family Amphiuridae. [2] It occurs on the seabed in the northeastern Atlantic Ocean and the North Sea, living semi-buried in the sand with only its arm tips projecting.

Contents

Description

Acrocnida brachiata has a flat disc up to 12 mm (0.5 in) in diameter and five slender, clearly-demarcated, articulated arms up to 180 mm (7 in) in length. It is greyish-brown in colour. It can be distinguished from other similar species by the transverse furrows in the plates at the bases of the arms, the ventral scales bearing small tubercles and by the presence of an outer mouth papilla which is quite distinct from the paired papillae inside the mouth. The arms, which like other brittle stars flex sideways rather than up and down, have a pair of tentacle scales on each joint as well as numerous spines. [2]

Distribution and habitat

Acrocnida brachiata occurs in the northeastern Atlantic Ocean and North Sea. It is common round the coasts of the British Isles where its depth range is from the lower shore down to about 40 m (130 ft). It is a benthic species, living on sandy bottoms and burying itself in the sediment, with only the tips of its arms projecting. [2] It often occurs in association with the burrowing sea urchin Echinocardium cordatum , [2] commonly known as the sea potato. [3]

Taxonomy

There is a marked difference in morphology between populations in the intertidal zone and those thought to be the same species living in the subtidal zone. Study of these differences led to the describing of a new species Acrocnida spatulispina by Sabine Stöhr and Delphine Muths in 2009, for the deeper water individuals. The brittle stars in the genus Acrocnida show morphological affinities with Amphiura chiajei , but less with Amphiura filiformis . [4]

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<i>Amphiura chiajei</i> Species of brittle star

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Acrocnida is a genus of brittle stars in the family Amphiuridae. The genus contains three members: Acrocnida brachiata, Acrocnida semisquamata, and Acrocnida spatulispina. There has also been observed hybridization between both Acrocnida brachiata and Acrocnida spatulispina. It is a fairly common genus, usually found along the coasts of Northwestern Europe, but with some species like semisquamata appearing around West Africa. Members of this genus primarily prefer intertidal and sub-tidal habitats, and they are they are less likely to be found in intertidal areas by comparison. This genus was not officially classified until 1926, by T. Gislén. One study found that due to the increased calcification that Acrocnida brachiata causes could be a potential source of Carbon Dioxide for not only the warm, shallow environments they live in, but also for the atmosphere.

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References

  1. 1 2 Stöhr, Sabine (2018). "Acrocnida brachiata (Montagu, 1804)". WoRMS. World Register of Marine Species . Retrieved 15 July 2018.
  2. 1 2 3 4 "Sand burrowing brittlestar (Acrocnida brachiata)". The Marine Life Information Network. MarLIN. Retrieved 15 July 2018.
  3. "Sea potato (Echinocardium cordatum)". The Marine Life Information Network. MarLIN. Retrieved 21 July 2018.
  4. Stöhr, Sabine; Muths, Delphine (2009). "Morphological diagnosis of the two genetic lineages of Acrocnida brachiata (Echinodermata: Ophiuroidea), with description of a new species". Journal of the Marine Biological Association of the United Kingdom. 90 (4): 831–843. doi:10.1017/S0025315409990749.