Trophodiscus almus
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| Trophodiscus almus | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Echinodermata |
| Class: | Asteroidea |
| Order: | Paxillosida |
| Family: | Astropectinidae |
| Genus: | Trophodiscus |
| Species: | T. almus |
| Binomial name | |
| Trophodiscus almus Fisher, 1917 [1] | |
Trophodiscus almus is a species of starfish in the family Astropectinidae. It is found in fairly deep waters in the Sea of Okhotsk, the Sea of Japan and around the Japanese island of Hokkaido. It is very unusual among starfish in that it broods its young on its upper surface. Its common name in Japanese is "Komochi-momiji".[2]
Trophodiscus almus is a five-armed pentagonal starfish growing to a diameter of about 33 mm (1.3 in). It has a wide disc and short, bluntly pointed arms. The aboral (upper) surface is slightly convex and is covered in paxillae, umbrella-shaped structures with spiny margins. The paxillae are larger near the inter-arm areas and smaller at the centre of the disc and near the arm-tips. The madreporite is about halfway from the centre of the disc to the margin, the anus is small, and there are respiratory structures known as papulae between and concealed by the paxillae. A notable feature are the 13 to 20 large calcareous plates, wider than they are long, that extend around the margins of each arm. There seem to be two different colour forms of this starfish. Some individuals have a bright red or orange-red aboral surface and a paler, reddish-brown oral (under) surface. Other individuals have a yellowish-green aboral surface and yellowish-brown oral surface. In both cases, the superomarginal plates are paler and contrast with the other parts.[3]