Quaternary sediments along the southernmost portion of the Brazilian coast are rich in fossil remains of various terrestrial and marine organisms. This paper presents a description of fossil irregular clypeasteroid echinoids found in this area, with observations on their taphonomy. The identified taxa are Encope emarginata (Leske) and Mellita quinquiesperforata (Leske), although the latter is v...

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...

two new species of an arbacioid echinoid, genus goniopygus, are reported for the first time from aptiansediments of baghin area, kerman, iran. the main features of the species lie in apical disc and peristomediameter. in goniopygus triangularis sp. nov., the periperoct is triangular in shape with three small, sunkentubercles, located alternatively adjacent to the periperoct, while goniopygus an...

Introduction: Echinoids (sea urchins) provide shelter for a variety of facultative or obligatory ectosymbionts. Objective: To evaluate the hypothesis that decapods and fishes prefer to associate with echinoid individuals species have longer spines. Methods: We visually studied frequency decapod crustaceans associated echinoids in shallow water (< 4 m) deeper (5-20 at Los Cabos, Baja Californ...

X-ray diffraction studies confirm that, with few exceptions, each skeletal element of echtinoderms is a single crystal of magnesium-rich calcite and that a relation exists between the shape of the element and the crystallographic a- and c-axes. The exceptions incluide the teeth of echinoids, and the calcareous ring as well as the anal teeth of holothurians. The tubercles of an echinoid plate be...

The acrosomal protein bindin attaches sperm to eggs during sea urchin fertilization. Complementary to ongoing functional biochemical studies, I take a comparative approach to explore the molecular evolution of bindin in a group of closely related free-spawning echinoid species. Two alleles of the mature bindin gene were sequenced for each of six species in the sea urchin family Strongylocentrot...