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excretion

(Encyclopedia)excretion, process of eliminating from an organism waste products of metabolism and other materials that are of no use. It is an essential process in all forms of life. In one-celled organisms wastes ...

feather star

(Encyclopedia)feather star, common name of a class of echinoderms that, as juveniles, are attached to the sea bottom by a stalk with rootlike branches; the mouth side faces upward. In the adult stage they break awa...

Humboldt, river, United States

(Encyclopedia)Humboldt, river, c.300 mi (480 km) long, rising in several branches in the mountains of NE Nev. It meanders generally west to disappear in Humboldt Sink, W Nevada. Along with its tributaries, the Humb...

Hot Springs National Park

(Encyclopedia)Hot Springs National Park, 5,549 acres (2,247 hectares), W central Ark.; est. 1921; nearly surrounded by the city of Hot Springs. Visited by Spanish explorer Hernando De Soto in 1541, the springs, lon...

Han, rivers, China

(Encyclopedia)Han. 1 River of S China, 210 mi (338 km) long, rising in W Fujian prov. and flowing S through Guangdong prov. to the South China Sea at Shantou; navigable for about 100 mi (160 km) upstream. The dense...

fjord

(Encyclopedia)fjord or fiord fyôrd [key], steep-sided inlet of the sea characteristic of glaciated regions. Fjords probably resulted from the scouring by glaciers of valleys formed by any of several processes, inc...

Poyang

(Encyclopedia)Poyang or P'o-yang both: pô-yäng [key], shallow lake, c.1,000 sq mi (2,590 sq km), N Jiangxi prov., SE China; one of China's largest lakes. It serves as a natural overflow reservoir for the Chang (Y...

swim bladder

(Encyclopedia)swim bladder, large, thin-walled sac in some fishes that may function in several ways, e.g., as a buoyant float, a sound producer and receptor, and a respiratory organ. The swim bladder, or air bladde...

Tantalus

(Encyclopedia)Tantalus tănˈtələs [key], in Greek mythology, king of Sipylos, son of Zeus and father of Pelops and Niobe. He was admitted to the society of the gods, but his abominable behavior aroused their ang...

whirlpool

(Encyclopedia)whirlpool, revolving current in an ocean, river, or lake. It may be caused by the configuration of the shore, irregularities in the bottom of the body of water, the meeting of opposing currents or tid...