The Echinoid Directory

Diadema savignyi (Michelin, 1845)

• Common name: English - Long-spined (sea) urchin, Black longspine urchin, Blue eye urchin, Banded diadem urchin, Savigny's (sea) urchin, Italian - Riccio diadema a bande, German - Diadem-Seeigel, French - Oursin diadème
• Systematics: Diadematidae, Diadematoida
• Distribution: Indo-Pacific
• Diet: Algae
• Feeding type: -
• Habitat: Warm shallow waters, tropical reefs, on coral or rock, coarse sand
• Depth range: Littoral - 70 m
• Maximum test size: 100 mm
• Behaviour: -

• Model

• Aboral, lateral and oral views

• MRI image slices

• Diadema setosum (from Agassiz 1872)
  

• http://www.nhm.ac.uk/research-curation/projects/echinoid-directory/taxa/taxon.jsp?id=1032

• Specimen ID: - freshly fixed specimen
• Expedition: -
• Collected in: 2006, Red Sea, Indian Ocean
• Collected by: -
• Identified by: A. Ziegler
• Specimen test size: 1.9 cm
• Scanning location: Würzburg 17.6T
• Scanning solution: Aqua dest. + Magnevist
  
• MRI dataset resolution: (40 µm)³
  

• Agassiz, A. 1872. Revision of the Echini. Illustrated Catalogue of the Museum of Comparative Zoology 7.

1. Recent analyses (Holland & Ghiselin 2008) have unequivocally demonstrated that this species does not possess - as indicated in the 3D models presented here - a siphon tube. Instead, this species is characterized by a so-called siphonal groove, i.e. a groove within the stomach rather than a separate tube. The structure indicated here as a siphon is in fact a haemal structure adjoining the stomach, the so-called inner marginal sinus.

• Holland, N.D. & Ghiselin, M.T. 2008. Siphons and siphonal grooves in the
  digestive systems of the Echinoidea (Echinodermata). Zoomorphology 127:
  259-264.