When significant mortality of the bathyal spatangoid echinoid Paleopneustes cristatus occurred under laboratory conditions, we investigated the cause and course of the disease by culturing and identifying internal pathogens, then experimentally infecting healthy urchins with isolates of the suspected disease organism. The pathogen was determined to be the gram-negative halophilic bacterium Vibr...

Two species of sea urchins (Colobocentrotus atratus and Echinometra mathaei) commonly co-occur on wave-swept intertidal shores in the Indo West Pacific. E. mathaei is a typical spiny urchin and is confined to cavities in the rock. In contrast, C. atratus has an unusual morphology, in which the spines are much reduced, and is found on substrata fully exposed to wave-induced velocities and accele...

for study of systematic and palaeoecology of mid-cretaceous oysters, the basab section, with 380 m thickness, west of kuhbanan, northwest of kerman, was measured and sampled. the section comprises a high diverse fauna (macro and microfossils), such as echinoids, bivalves, oysters, brachiopods, gastropods, corals, ammonites, foraminifers and ostracods. the fossils indicate late aptian- early cen...

The feeding larvae of many echinoids develop long postoral arms relative to body length when food is sparse but relatively short abundant, a response thought adaptively adjust capability. However, in an important recent study, Dendraster excentricus exhibited this food-conditioned plasticity only reared at high density typical laboratory cultures; lower more representative larval densities natu...