Abderaz Formation is one of the Upper Cretaceous formations in the Kopet-Dagh sedimentary basin. A stratigraphic section from the mentioned formation is selected for detailed systematic description with regard to echinoids. Numerous well preserved representatives of the families Mircrasteridae wright, 1857 and Echinocorythidae Lambert, 1920 are described from the Ghaleh-Zoo stratigraphic sectio...

BACKGROUND Apart from its application in human diagnostics, magnetic resonance imaging (MRI) can also be used to study the internal anatomy of zoological specimens. As a non-invasive imaging technique, MRI has several advantages, such as rapid data acquisition, output of true three-dimensional imagery, and provision of digital data right from the onset of a study. Of particular importance for c...

Salmacis sphaeroides (Linnaeus, 1758) is one of the regular echinoids, occuring in the warm Indo-West Pacific, including Johor Straits, between Malaysia and Singapore. In order to investigate the developmental basis of morphological changes in embryos and larvae, we documented the ontogeny of S. sphaeroides in laboratory condition. Gametes were obtained from adult individuals by 0.5 M KCl injec...

Populations of sea urchins often fluctuate greatly in density. The density of sea urchins is usually inversely correlated with the abundance of macrolagae. It is argued that fluctuations in density are a predictable consequence of the unique morphology and physiology of sea urchins. An extraordinary ability to accomodate food Limitation through variations in growth rate means that surv~vorship ...