Echinoidea

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Echinoidea

[‚ek·ə′noid·e·ə]
(invertebrate zoology)
The sea urchins, a class of Echinozoa having a compact body enclosed in a hard shell, or test, formed by regularly arranged plates which bear movable spines.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
Nevertheless, because sand dollars (like most marine invertebrates) have external fertilization and no parental care, opportunities for non-genetic paternal contributions to embryonic and larval development are limited to substances or organelles in the sperm itself (such as the centriole) and paternal imprinting {via, e.g., methylation patterns; see, e.g., McBirney et al., 2017), of which there have been no reports to date in echinoids (sand dollars and urchins).
Those bioclastic packstones contain echinoid debris, small lituolids, and angular, silt-sized quartz (Fig.
World patterns of developmental mode in echinoid echinoderms.
After showing that these current theories are not sufficient to explain the high proportion of brooding in antarctic echinoids, we propose an alternative hypothesis based on the dispersal abilities of species and discuss the consequences of such a strategy on the long-term evolution of the clade.
crinoids echinoids gastropods brachiopods and bryozoans) indicate the middle shelf normal subtidal setting while the micrite matrix suggests low energy conditions (Wright 1992; FlA1/4gel2004).
They contain abundant lithoclasts and reworked bioclasts of very shallow water faunas (bivalve fragments, orbitoidids, echinoids).
In addition, levels of herbivory have declined on Jamaican reefs in recent decades due first to chronic overfishing (Munro 1983) and secondly to a sustained reduction in abundance of the major grazing echinoid, Diadema antillarum, caused by mass mortality from disease (Hughes et al.
By observation of the development and feeding performance of these larvae, I show that many of the important features of embryos and larvae that are characteristic of feeding larval development of echinoids are found in B.
Following previous descriptions and knowing that echinoids (sea urchins) are gonochoric, we argue that existence of ovotestis in Loxechinus albus corresponds to an isolated phenomenon that perhaps depicts a sequential hermaphroditism detected on this occasion first as male, then female.