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brittlestar

(Encyclopedia)brittlestar, common name for echinoderms belonging to the class Ophiuroidea. The name is derived from their habit of breaking off arms as a means of defense. New arms are easily regenerated. They are ...

dream

(Encyclopedia)dream, mental activity associated with the rapid-eye-movement (REM) period of sleep. It is commonly made up of a number of visual images, scenes or thoughts expressed in terms of seeing rather than in...

ectoderm

(Encyclopedia)ectoderm, layer of cells that covers the surface of an animal embryo after the process of gastrulation has occurred. This outer layer, together with the endoderm, or inner layer, is present in all ear...

connective tissue

(Encyclopedia)connective tissue, supportive tissue widely distributed in the body, characterized by large amounts of intercellular substance and relatively few cells. The intercellular material, or matrix, is produ...

photochemistry

(Encyclopedia)photochemistry, study of chemical processes that are accompanied by or catalyzed by the emission or absorption of visible light or ultraviolet radiation. A molecule in its ground (unexcited) state can...

Bradbury, Ray

(Encyclopedia)Bradbury, Ray (Raymond Douglas Bradbury) brădˈbĕrˌē, –bərē [key], 1920–2012, American writer, b. Waukegan, Ill. A popular and prolific writer of science fiction who did much to bring the ge...

badger

(Encyclopedia)badger, name for several related members of the weasel family. Most badgers are large, nocturnal, burrowing animals, with broad, heavy bodies, long snouts, large, sharp claws, and long, grizzled fur. ...

sun grebe

(Encyclopedia)sun grebe, common name for a tropical, mainly aquatic bird of the family Heliornithidae. Sun grebes, also called finfoots, are remarkable for their colorful, puffy-toed, webbed feet, which may serve a...

Sacks, Oliver Wolf

(Encyclopedia)Sacks, Oliver Wolf, 1933–2015, British neurologist and author, b. London, educated at Queen's College, Oxford. In 1960 he moved to the United States, where he continued his medical training. He bega...

Shevchenko, Taras Hryhorovych

(Encyclopedia)Shevchenko, Taras, 1814–1861, Ukrainian poet, writer, and artist, b. Ukraine, studied at the St. Petersburg Academy of Art. The premier Ukrainian poet...