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Phylum Echinodermata > Class Echinodea > sea urchins > Genera Salmacis
White salmacis urchin
Salmacis sphaeroides
Family Temnopleuridae
updated Apr 2020

Where seen? This almost-cuddly white sea urchin is seasonally common on our Northern shores among seagrasses. At some times, many of these sea urchins are seen, and then none seen for some time. On Cyrene Reef, gatherings of many of these sea urchins are sometimes seen.

Features:
Body diameter 5-8cm, white. Spines short (1-1.5cm) and sharp, about the same length. Spines on the underside have spade-like tips. Some have white spines with green or maroon bands. It has long tube feet and is often seen carrying all kinds of things from shells to seaweeds. It can quickly gather these things to cover itself. This behaviour may help camouflage it or shield it from sunlight.

Changi, May 08

Sometimes gathered in large numbers.
Cyrene Reef, Apr 07

Carrying stuff.
Beting Bronok, May 06

White spines with maroon bands.
Changi, May 08

White spines with green and maroon bands.
Cyrene Reef, Apr 08

Flattened spines on underside.
Changi, May 06
What does it eat? It eats seaweeds.

What eats them? Examination of tests (skeleton of a dead sea urchin) suggest that large snails might prey on them.

Home on an urchin:
Some animals live on this prickly animal. This includes Parasitic snails, the Zebra crab and sometimes, the Urchin-mouth worm is found curled around the mouth.

Hole with 'burn' mark suggests the urchin was attacked by a Helmet snail.
Changi, May 08

Worm-like thing seen on the underside.
Changi, Oct 10

Parasitic snails seen on the urchin
Cyrene, May 17
Photo shared on Singapore Biodiversity Records.



Zebra crab (Zebrida adamsii) seen on the urchin.
Changi, Jun 17
Photo shared on Singpaore Biodiversity Records.

White salmacis urchin (Salmacis sphaeroides)

White salmacis urchins on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores


Sembawang Beach, Sep 20
Photo shared by Marcus Ng on facebook.

Beting Bronok, Jun 10
Photo shared by Loh Kok Sheng on flickr.

Chek Jawa, Apr 08
Photo shared by Tan Sijie on his blog.


Seringat-Kias, Aug 12
Photo shared by Loh Kok Sheng on flickr.

Cyrene Reef, Aug 11
Photo shared byJames Koh on his blog.

Pulau Tekukor, May 10
Photo shared by Neo Mei Lin on her blog.


Beting Bemban Besar, Mar 17
Photo shared by Juria Toramae on facebook.


Acknowlegment
Grateful thanks to Dr Frederic Ducarme for identifying these sea urchins.

Links

References

  • Neo Mei Lin. Zebra crab (Zebrida adamsii) on a sea-urchin (Salmacis sphaeroides) at Changi Beach. 28 July 2017. Singapore Biodiversity Records 2017: 96 ISSN 2345-7597. National University of Singapore.
  • Ying Lynette Shu Min. 29 Sep 2017. Parasitic snails, Vitreobalcis sp., on white sea urchins (Salmacis sphaeroides) at Cyrene Reef. Singapore Biodiversity Records 2017: 123-124.
  • Schoppe, S., 2000. Echinoderms of the Philippines. Times Edition, Singapore. 144 pp.
  • Miskelly, Ashely. 2002. Sea Urchins of Australia and the Indo-Pacific. Capricornia Publications. 180pp.
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