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Phylum Echinodermata > Class Stelleroida > Subclass Asteroidea
Cryptic sea star
Cryptasterina sp.

Family Asterinidae
updated Mar 2020
Where seen? This little sea star hides under stones near the mid-water mark. At low tide it clamps tight to the surface almost like a limpet. It is found on natural rocky shores of our Southern shores.

Features: Diameter with arms (3-4cm). 5 arms that are so short that the animal appears almost pentagonal. Clamping tight to the surface, the body is sometimes in a hump in the centre. Upperside with tiny holes through which short stubby
transparent finger-like structures (papulae) emerge when it is submerged. Colours plain or mottled beige, brown or grey that camouflages it perfectly with the rocks it clings to. Underside pale without any markings. Tube feet short, tipped with suckers.

According to Lane, the species are very difficult to tell apart even under the microscope and molecular methods are needed to distinguish the species.

According to Marsh and Fromont, in Australia, Cryptasterina hystera is found in mangrove habitats under small intertidal rocks on mud and sandy mud. While Cryptasterina pentagona is found on or under rocks in the high intertidal.

What does it eat? It grazes on algae, detritus, small animals and the biofilm found on the surface of the stone.

Status and threats: This sea star is listed as 'Vulnerable' in the Red List of threatened animals of Singapore.

Pulau Semakau, May 08

Stubby papulae stick out on the upper surface

Several found under a stone.
Pulau Semakau, May 08

Underside

Cryptic sea stars on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores


Berlayar Creek, Oct 15
Shared by Jonathan Tan on facebook.

Berlayar Creek, Oct 15
Shared by Jonathan Tan on facebook.

Berlayar Creek, Oct 17
Shared by Loh Kok Sheng on facebook.


Berlayar Creek, Feb 20
Shared by Loh Kok Sheng on facebook.
 


Lazarus, Jul 11
Shared by Loh Kok Sheng on his blog.

Lazarus, Jul 11
Shared by Loh Kok Sheng on his blog.

Lazarus, Jul 11
Shared by Loh Kok Sheng on his blog.


Pulau Semakau South, Feb 16
Shared by Loh Kok Sheng on facebook.
 

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.
  • Davison, G.W. H. and P. K. L. Ng and Ho Hua Chew, 2008. The Singapore Red Data Book: Threatened plants and animals of Singapore. Nature Society (Singapore). 285 pp.
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