Sand Dollars (species: Arachnoides placenta) in taxonomy (Gaia Guide)
Animalia > Echinodermata > Echinozoa > Echinoidea > Euechinoidea > Irregularia > Neognathostomata > Clypeasteroida > Clypeasterina > Clypeasteridae > Arachnoidinae > Arachnoides > Arachnoides placenta (gallery)
Arachnoides placenta
Sand Dollars


©Lyle Vail: Arachnoides placenta exposed at low tide at Watson's Bay beach - sand has been washed off

©Lyle: Tracks of two Arachnoides placenta at low tide, Watson's Bay beach.

©Lyle: Arachnoides placenta in its track with sand removed

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Kingdom Animalia
Phylum Echinodermata
Class Echinoidea
Order Clypeasteroida
Family Clypeasteridae
Genus Arachnoides
Species Arachnoides placenta
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Distinguishing features

Arachnoides placenta is a small sand dollar that grow to about 50 mm in diameter. It is flat underneath and only slightly raised on the upper side. The edge between the surfaces is very fine. It is usually covered with a thin layer of sand, leaving a track as it moves at low tide.

Size

  • Size data has not been obtained.

Depth range

  • Depth range data is not yet available.

Synonyms

Distribution


©Atlas of Living Australia: Australian distribution

Local abundance

  • Lizard Island: At Lizard Island, Arachnoides placenta has so far only been found in the low intertidal zone at Watson's Bay beach where it is relatively common.

Web resources

References

  • Clark, A.M. and F.W.E. Rowe (1971). Monograph of shallow-water Indo-west Pacific echinoderms British Museum (Natural History), London.