species: Diadema savignyi in Lizard Island area: all known taxa (Lizard Island Field Guide)
Diadema savignyi

©Anne Hoggett: A small Diadema savignyi (test diameter about 7 cm) at Lizard Island at night

©Anne Hoggett: Diadema savignyi at Big Vicki's Reef, Lizard Island, at night.
Kingdom Animalia
Phylum Echinodermata
Class Echinoidea
Order Diadematoida
Family Diadematidae
Genus Diadema
Species Diadema savignyi



Distinguishing features

Test is circular up to 8 cm diameter and depressed. Primary spines are very long (to 30 cm), thin, and hollow. Secondary spines are shorter and thinner and are not easily seen in living animals.

Spines are generally black but in some specimens they are white or banded black and white. Tissue covering the test is black and the anal cone is black, without an orange ring. Irridescent blue lines run down the interambulacra, often with a white spot where the lines bifurcate.


  • Up to 8 cm (test diameter)
  • Up to 30 cm (spine length)

Depth range

  • Depth range data is not yet available.


Similar taxa


©Atlas of Living Australia: Australian distribution

Daytime exposure tendencies

  • typically hidden during the day
  • )

Web resources


References that assist with identification

  • Miskelly, A. (2002). Sea Urchins of Australia and the Indo-Pacific 180 pp. Capricornia Publications, Sydney, Australia.

Other references

  • Young, M.A.L. and D.R. Bellwood (2011). Diel patterns in sea urchin activity and predation on sea urchins on the Great Barrier Reef. Coral Reefs, 30: 729-736. LIRS catalog number 1483.