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An echinoderm of the class Echinoidea, which includes the sand dollars and sea urchins.


(ɪˈkaɪnɔɪd; ˈɛkə-)
(Animals) any of the echinoderms constituting the class Echinoidea, typically having a rigid ovoid body. The class includes the sea urchins and sand dollars
(Animals) of or belonging to this class


(ɪˈkaɪ nɔɪd, ˈɛk əˌnɔɪd)

1. any echinoderm of the class Echinoidea, comprising sea urchins and sand dollars, characterized by a rounded, armless body and a rigid endoskeleton with movable spines.
2. of, belonging to, or resembling the echinoids.
[1850–55; < New Latin Echinoidea; see echinus, -oidea]
References in periodicals archive ?
The rock-boring urchin (Echinometra lucunter) is a regular tropical echinoid characterized by the color of the test (or shell) and spikes ranging from dark tones to black.
Larval arm movements and the musculature that animates them may be characters that are plesiomorphic to larvae of crown group echinoid taxa (Wray, 1992) and appear to vary among their descendants.
Echinoid community structure and rates of herbivory and bioerosion on exposed and sheltered reefs.
Contradictory findings regarding behavioral cues, both among and within species and locales, make it difficult to develop a generalized model of echinoid aggregation and overgrazing.
setosum is a stenohaline echinoid that could not be able to survive and develop if the salinity range is less than28 or more than 37 ppt.
antillarum; whereas Prado, Carmichael, Watts, Cebria & Heck, (2012) experimentally determined the trophic enrichment factor for the green echinoid Lytechinus variegatus.
Taxonomic significance of spine morphology in the echinoid genera Diadema and Echinothrix.
Sea urchins belong to the class Echinoidea, one of four classes in the phylum Echinodermata, and here specialists describe echinoid species and represent them with images.
The northern limb of the syncline is accessible by vehicles along a dirt track around the western side of the jebel and has been a fruitful site for the collection of echinoid specimens by palaeontologists of the Natural History Museum, London.
An echinoid fossil in the wall of <BBurberry's on Bond Street
Biology of the Echinoid, Tripneustesgratilla Fed the Seagrass, Halophilastipulacea in the Gulf of Aqaba, Jordan.
The non-rudist bivalves mentioned above occur together with scattered moulds of gastropods (Ampullina and Tylostoma), abundant echinoid spines, several Diplopodia, and an isolated pycnodontid fish tooth (Coelodus).