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

Family Oreasteridae
updated Jul 2020
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 among and under rocks and stones and often overlooked.

It appears that if they are overturned, they can right themselves by inflating the body so the upperside is very round. The action of waves then turns the sea star the right side up. See the video of this below by Yuejie Zheng.

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.

Terumbu Bemban, Jul 11

Tube feet on upper surface

Upper surface.

Underside

Underside.
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. According to Marsh and Fromont, it eats corals such as Acropora, Pocillopora and Porites. It also eats echinoids (sand dollars, sea urchin, heart urchins) as well as biofilm growing on the sea bottom.

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. According to Marsh and Fromont, pearlfish (Carapidae) have been seen sheltering inside the sea star. But this has not been observed for those stars seen at low tide on the intertidal.

Cushion babies: According to Marsh and Fromont, the sexes are separate and up 7 million small eggs can be spawned in one event. When fertilised, they develop into planktonic larvae that swim near the surface for about 18 days before settling to the bottom to metamorphose into a juvenile sea star. It can take 2 years from metamorphosis to the adult 'cushion' form.

Cushion stars on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores

How an upside down cushion star rights itself!


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.



Cyrene Reef, May 08

Photo shared by Loh Kok Sheng on his blog.

Cyrene Reef, Sep 22
Photo shared by Kelvin Yong on facebook.

Terumbu Semakau, May 10
Photo shared by Loh Kok Sheng on his blog.


Terumbu Hantu, Apr 12
Photo shared by Jose Hong on facebook.

Terumbu Hantu, Apr 12
Photo shared by Sam Yeo on facebook.

Terumbu Semakau, Jun 12
Photo shared by James Koh on his blog.


Pulau Semakau, Jul 08
Photo shared by Loh Kok Sheng on his blog.

Pulau Semakau, May 08
Photo shared by Lin Juanhui on her flickr .


Pulau Semakau South, Jan 20
Photo shared by Jianlin Liu on facebook.

Pulau Semakau East, Jul 16
Photo shared by Richard Kuah on facebook.

Terumbu Semakau, Jun 10
Photo shared by Loh Kok Sheng on his blog.


Beting Bemban Besar, Apr 10
Photo shared by James Koh on his blog.

Beting Bemban Besar, Aug 18
Photo shared by Jianlin Liu on facebook.
 


Terumbu Bemban, Apr 11

Photo shared by Loh Kok Sheng on his blog.

Terumbu Bemban, Apr 11

Photo shared by Loh Kok Sheng on his blog.



Terumbu Pempang Tengah, Jun 15

Photo shared by Jianlin Liu on facebook.

Terumbu Pempang Tengah, May 21

Photo shared by Loh Kok Sheng on facebook.

Terumbu Pempang Tengah, May 23

Photo shared by Liz Lim on facebook.


Pulau Senang, Jun 10

Photo shared by Loh Kok Sheng on his flickr.

Pulau Biola, May 10

Photo shared by Marcus Ng on flickr.

Pulau Berkas, Feb 22
Photo shared by Loh Kok Sheng on facebook.

Links

References

  • Loisette M. Marsh and Jane Fromont. Field Guide to Shallow Water Seastars of Australia. 2020. Western Australian Museum. 543pp.
  • Lane, David J.W. and Didier Vandenspiegel. 2003. A Guide to Sea Stars and Other Echinoderms of Singapore. Singapore Science Centre. 187pp.
  • Didier VandenSpiegel et al. 1998. The Asteroid fauna (Echinodermata) of Singapore with a distribution table and illustrated identification to the species. The Raffles Bulletin of Zoology 1998 46(2): 431-470.
  • Chou, L. M., 1998. A Guide to the Coral Reef Life of Singapore. Singapore Science Centre. 128 pages.
  • Coleman, Neville. 2007. Sea stars: Echinoderms of Asia/Indo-Pacific. Neville Coleman's Underwater Geographic Pty Ltd, Australia.136pp.
  • Schoppe, Sabine, 2000. Echinoderms of the Philippines: A guide to common shallow water sea stars, brittle stars, sea urchins, sea cucumbers and feather stars. Times Edition, Singapore. 144 pp.
  • Gosliner, Terrence M., David W. Behrens and Gary C. Williams. 1996. Coral Reef Animals of the Indo-Pacific: Animal life from Africa to Hawai'I exclusive of the vertebrates Sea Challengers. 314pp.
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