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echinoids
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| Phylum Echinodermata > Class Echinodea > Order Clypeasteroida |
| Cake
sand dollar Arachnoides placenta Family Clypeasteridae updated Aug 10 Where seen? This rather featureless disk-shaped animal is commonly seen on some of our Northern shores, on sand bars and sandy areas near seagrasses. Often found in groups of large numbers of individuals, half buried in the sand. Sometimes also seen on the Southern shores. Features: Body diameter 2-8cm. Seen in various sizes, some may be tiny (about the size of a 10cent coin). It has no slots in the body. While the star-shaped petalloid is not very obvious in living specimens, they are clearly seen in the test of a dead sand dollar. The colours of a living sand dollar may range from deep reddish-purple, to brownish-purple or beige. Sometimes, many sand dollars are observed flipped over with their undersides broken. From the prints around the sand dollars, it seems they were flipped and pecked by birds. Strangely, some sand dollars are flipped but unpecked. Perhaps only egg-bearing females are pecked? Kok Sheng also shared a video clip of hermit crabs arguing over a sand dollar. |
 Changi, May 08  Upperside. |
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 Underside. |
 Mouth on the underside. |
 Tanah Merah, Mar 10  With a hole. Recovering from a wound? |
 Chek Jawa, Mar 10  It seems birds have flipped over some and pecked out the underside. |
 Chek Jawa, Mar 10  Some are flipped but not harmed. Only egg-bearing females are pecked? |
 Is this Grey bonnet snail eating a sand dollar? Cyrene Reef, May 11 Photo shared by Marcus Ng on flickr. |
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Cake sand dollars on Singapore shores
 Changi, Jun 06 |
 Upperside of test. |
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 Underside of test |
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 Living sand dollars buried just beneath the sand Chek Jawa, Dec 01 |
 They are sometimes found in huge numbers. Chek Jawa, Jan 09 |
 Sometimes, sand dollars are tiny! Tanah Merah, Apr 05 |
 Lazarus Island, Jun 09 |
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video clips and more photos of cake sand dollars on Singapore shores
northern shores part 1 | part 2 | part 3
southern shores part 1 | part 2 | part 3
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