Scaly brittle star
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Scaly brittle star ( Amphipholis squamata ) |
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| Amphipholis squamata | ||||||||||||
| ( Delle Chiaje , 1828) |
The Scaly brittle star ( Amphipholis squamata ) is a brittle star in the genus Amphipholis in the family Amphiuridae. This brittle star is a complex of cryptospecies . The species is capable of bioluminescence in the arms through specialized cells (photocytes) .
features
The scaly brittle star is a small gray to bluish white brittle star. The color is variable, however, there are also beige, orange, dark brown, black and dotted variations. The central disc reaches a diameter of about 5 mm, the 5 arms are about 4 times as long as the diameter of the central disc. The disc is covered with rather small scales on both sides, from which the primary plates can hardly be distinguished. The radial shields are small, about 1/3 of the disk radius, the two radial shields of one arm touch. Its bursal fissures are long and wide. The mouth shields are diamond-shaped , at the top of the jaw there are a pair of infradental papillae and two oral papillae on each side of the jaw. There are 3 to 4 pairs of short conical spines on each arm segment. The dorsal arm plates in the arm part towards the center of the body (proximal) are wider than long, rounded triangular, the ventral triangular and cut off at the top. There is a tentacle scale each on the belly and side arm plates.
distribution
The scaly brittle star is a widespread cosmopolitan of temperate and warm temperate waters, it is not found in the polar region . He takes care of brood, there is no free-swimming larval stage. Despite this direct evolution, usually associated with poor geographical distribution and habitat occupation, it is believed to be the most widespread species of all coastal ophiurids . Reasons for this could be the presumed multitude of cryptic taxa and the passive distribution by drifting macroalgae that inhabit the species. Other sources see migration along the coasts as the reason for the global spread.
Habitat and way of life
The scaly brittle star can be found from the intertidal zone to depths of around 250 m to 1200 m, depending on the literature. It lives under stones and the shells of marine animals, but also on sandy soil, rocky soil and on living organisms such as sponges , bog animals , corals , molluscs , poly-bristles and seaweed . Scaly brittle stars are simultaneous hermaphrodites , i.e. they form seeds and egg cells at the same time. They are capable of self-fertilization . However, mating with conspecifics is probably common, with the sperm being released into the bursa, an inverted pocket that is both a respiratory organ and serves to export the sex products of an approached partner. One egg is developed per bursa and pass through several larval stages before the developed young animals with a disc diameter of about 1 mm are released. Brood care is carried out, there is no free-swimming larval stage. After about 8 months and a disc diameter of 1.8 mm, the young are in turn able to reproduce and remain fertile until the end of their lifespan of about 18 months. Scaly brittle stars are omnivores . They filter edible particles and plankton from the current , besides they are detrivorous, i.e. they feed on detritus . In order to escape enemies, they can throw off their arms ( autotomy ), lighting of the thrown off arms (bioluminescence) can support the escape.
Research history and taxonomy
The Scaly brittle star was in 1828 by Delle Chiaje in Memorie su la storia e notomia degli animali senza vertebre del Regno di Napoli Vol. III as Asteria squamata first described . It is likely, however, that the species was already described by Leach in 1815 as Ophiura elegans . Due to the widespread use, more names were added, as of August 2020 WoRMS is naming 26 synonymous names. Before 1900, no unanimity could be reached regarding the species addition , but important naturalists of the 19th century such as Müller and Troschel (1842), Sars (1861) and Lyman (1882) used the species addition squamata . Clark noted in 1987 that, according to Thomas (1966), the species is the " most frequently mentioned amphiurid brittle star in the scientific literature " and that it is particularly important to stabilize the species addition. Due to the inadequacy of the information Leach provided and the lack of type material, as well as the fact that Amphipholis squamata is widely used, Clark recommended that the International Commission on Zoological Nomenclature should suppress A. elegans (Leach, 1815), despite its naming priority.
Individual evidence
- ↑ Amphipholis squamata at World Register of Marine Species (WoRMS)
- ↑ a b c d e f Alitto et al. : Shallow-water brittle stars (Echinodermata: Ophiuroidea) from Araçá Bay (Southeastern Brazil), with spatial distribution considerations. In: Zootaxa 4405, No. 1, 2018, pp. 43–45. ( Online )
- ↑ a b c d e M. J. de Kluijver, SS Ingalsuo: Macrobenthos of the North Sea - Echinodermat. Amphipholis squamata at Marine Species Identification Portal
- ↑ a b Timothy O'Hara, Mary Byrne: Australian echinoderms: Biology, Ecology and Evolution. CSIRO, 2017, ISBN 978-1486307623 , p. 342.
- ↑ a b c d G. Attaran-Fariman, A. Beygmoradi: The first report of Amphipholis squamata (Delle Chiaje, 1829) (Echinodermata: Ophiuroidea) from Chabahar Bay –northern Oman Sea. In: Iranian Journal of Fisheries Sciences 15 (3), 2016, pp. 1254–1261. ( Online )
- ↑ R. Sponer, M-S. Roy: Phylogeographic analysis of the brooding brittle star Amphipholis squamata (Echinodermata) along the coast of New Zealand reveals high cryptic genetic variation and cryptic dispersal potential. In: Evolution 56 (10), 2002, pp 1954-1967. ( Online )
- ^ A b Scoresby Shepherd, Graham Edgar: Ecology of Australian Temperate Reefs: The Unique South. CSIRO, 2014, ISBN 978-1486300099 , p. 241.
- ↑ Stefano Delle Chiaje: Memorie su la storia e notomia degli animali senza vertebre del Regno di Napoli. Vol. III, p. 74. ( Online )
- ^ AM Clark: Asterias squamata Delle Chiaje, 1828 (currently Amphipholis squamata; Echinodermata, Ophiuroidea): proposed conservation of the specific name. In: The Bulletin of zoological nomenclature Vol. 44, 1987, pp. 246-247. ( Online )
