Phylum Echinodermata > Class Stelleroida > Subclass Asteroidea
Cushion star
Culcita novaeguineae

Family Oreasteridae
updated Jan 14

Where seen? This almost globular sea star is sometimes seen, especially on the larger reefs on our Southern shores. Usually among live hard corals. Out of water, it may 'deflate' and appear more star-shaped. It is more often encountered by divers in deeper waters, but are sometimes also found on reef flats. Usually seen alone or widely spaced apart. According to Gosliner, this is considered the most widespread and common species of cushion star.

Features:
Diameter with arms 12-20cm. Arms very short, body almost globular. According to Lane, the thick calcified body walls and rounded shape makes it more difficult for fish and other predators to bite it. The upperside has a texture of circular shapes and little bumps. When submerged tiny transparent finger-like structures (papulae) might be seen on the upperside. The underside is flat with five grooves and short tube feet with sucker-shaped tips. They come in a wide range of colours and patterns. Juveniles are flatter, more star-shaped with short arms edged with large marginal plates. These are usually well hidden under stones and are rarely seen.

Young cushion stars are sometimes mistaken for other large sea stars. Here's more on how to tell apart large sea stars seen on our shores.

What does it eat? It is reported that they eat live corals similar to the feeding habits of the dreaded Crown-of-thorns sea star (Acanthaster planci). According to Chow, it has been found to eat some species of hard corals. But according to Lane, those in Singapore evert their stomachs over immobile animals or even on sediments to eat the organic particles found there. According to Gosliner, Culcita species gains at least part of their nutrition from eating coral polyps as well as seaweeds. While Schoppe says they eat coral polyps and other immobile invertebrates.

Cushion friends: According to Schoppe and to Gosliner, the commensal shrimp Periclimenes soror is often seen on the underside as well as upperside of the sea star. But this has not been observed for those stars seen at low tide on the intertidal.

Terumbu Bemban, Jul 11
Tube feet on upper surface
Upper surface.

Underside.


Juvenile cushion star

Cyrene Reef, Mar 09
Shared by Loh Kok Sheng on his blog.

Juvenile cushion star

Pulau Senang, Jun 10

Shared by Loh Kok Sheng on his flickr.

Juvenile cushion star

Cyrene Reef, Jun 08
Photo shared by Chim Chee Kong on his flickr.

Cushion stars on Singapore shores

Photos for free download from wildsingapore flickr

more photos of cushion stars of Singapore shores

Links

References

www.flickr.com
FREE photos of sea stars. Make your own badge here.
 
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