| 词条 | Euretaster insignis |
| 释义 |
| name = Euretaster insignis | image = Euretaster insignis.jpg | regnum = Animalia | phylum = Echinodermata | subphylum = Eleutherozoa | classis = Asteroidea | ordo = Velatida | familia = Pterasteridae | genus = Euretaster | species = E. insignis | binomial = Euretaster insignis | binomial_authority = Sladen, 1882[1] | synonyms = *Retaster insignis Sladen, 1882 | synonyms_ref = [1] }} Euretaster insignis, commonly known as the striking sea star,[3] is a species of starfish in the family Pterasteridae found in the central west Pacific Ocean. It is one of only three species in the order Velatida to be found in shallow water in the tropics. The young are brooded in a cavity underneath a "supradorsal" membrane. Taxonomy and evolutionThis starfish was first described in 1882 by the marine biologist W. P. Sladen as Retaster insignis, but has since been moved by W. K. Fisher to the newly created genus Euretaster.[2] The order Velatida are presumed to be the earliest lineage of living sea stars to diverge from the ancestral line, their closest living relatives being the abyssal sea daisies in the order Peripodida. The three members of the genus Euretaster are the only tropical, shallow-water species in the order Velatida, the remaining members living at abyssal depths. It might be presumed that the order has its origin in deep water, however there are numerous shallow water fossils of velatidans dating from the Cretaceous period and it seems that these ancient forms have largely been driven out of shallow water habitats by competition from recent, more-advanced taxa.[3] DescriptionThis small starfish is star-shaped and has five stubby arms. The aboral (upper surface) has an inflated appearance due to it being covered by a "supradorsal" membrane; this is supported by bundles of spinelets borne on the flat plates that are arranged in a mosaic pattern on the cuticle below. This membrane encloses a supradorsal cavity filled with sea water, which is connected to the water column by a central osculum (aperture), which opens and closes periodically.[6] The membrane has a reticulated pattern of ridges and small conical protrusions. It is patterned in some combination of red, white and brown.[3] Distribution and habitatEuretaster insignis is native to the tropical western central Pacific Ocean from the intertidal zone down to about {{convert|132|m|ft|-1|abbr=on}}. It is found on coral reefs, rocky coasts,[4] sand and muddy rubble.[5]EcologyThe sexes are separate in Euretaster insignis. Instead of being planktonic, the developing embryos are brooded in the supradorsal cavity, and even receive nourishment from the mother in the form of a mucosal secretion from the cuticle; they receive this because their presence irritates the lining of the cavity causing it to secrete the fluid in a process that has been described as "cannibalistic ectoparasitism".[3] The larvae are brooded until they are about {{convert|1|cm|in|1|abbr=on}} in diameter at which time they are liberated as juvenile starfish into the sea.[3] References1. ^1 {{cite WoRMS |author=Mah, Christopher |year=2018 |title=Retaster insignis Sladen, 1882 |id=292741 |accessdate=13 March 2019 |db=Asteroidea}} 2. ^{{cite WoRMS |author=Mah, Christopher |year=2018 |title=Euretaster Fisher, 1940 |id=206389 |accessdate=14 March 2019 |db=Asteroidea}} 3. ^1 2 3 {{cite web |url=https://reefbuilders.com/2015/05/18/rarely-striking-sea-star/ |title=The rarely seen Striking Sea Star |author=Rowlett, Joe |date=18 May 2015 |publisher=Reef Builders |accessdate=13 March 2019}} 4. ^1 {{cite web |url=https://www.sealifebase.ca/summary/Euretaster-insignis.html |title=Euretaster insignis (Sladen, 1882) |publisher=FishBase |accessdate=13 March 2019}} 5. ^1 {{cite book|author1=O'Hara, Timothy|author2=Byrne, Maria|title=Australian Echinoderms: Biology, Ecology and Evolution |url=https://books.google.com/books?id=EtkqDwAAQBAJ&pg=PA278 |year=2017 |publisher=Csiro Publishing |isbn=978-1-4863-0763-0 |page=278}} 2 : Pterasteridae|Animals described in 1882 |
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