Dendrasteridae, Lambert, 1900

Ziegler, Alexander, Lenihan, Jennifer, Zachos, Louis G., Faber, Cornelius & Mooi, Rich, 2016, Comparative morphology and phylogenetic significance of Gregory’s diverticulum in sand dollars (Echinoidea: Clypeasteroida), Organisms Diversity & Evolution (New York, N. Y.) 16 (1), pp. 141-166 : 158

Dendrasteridae

Two species of Dendraster were incorporated into the present study. Gregory’ s diverticulum is present in Dendraster excentricus ( Fig. 4p–t ) and Dendraster laeois . A relatively comprehensive X-ray imaging series is available for D. excentricus , spanning specimens from 3 to 50 mm test length. In this species, Gregory’ s diverticulum was found to be present in its fully distended form up to a test length of 50 mm, while remnants of the organ were still visible up to a test length of 80 mm. In 45 out of 52 specimens of D. excentricus (87 %), sediment was found inside the diverticulum.

Figures

Fig. 4 Absence of Gregory’s diverticulum in Marginoproctus (a–e) as well as presence and shape of the organ in the Scutellidae (f–o) and Dendrasteridae (p–t). The figure shows selected X-ray images and a photograph of a dissected specimen. a–e Marginoproctus djakonooi (3, 3, 5, 6, 9 mm test length); f–j Scaphechinus griseus (2, 6, 9.5, 35, 36 mm);