sea anemone \3-,ne-m9-,ne\ Any of more than 1,000 cnidarian spe¬ cies in the order Actiniaria, found from the tidal zone of all oceans to depths of more than 30,000 ft (10,000 m) and occasionally in brackish water. Species vary from less than 1 in. (3 cm) to about 5 ft (1.5 m) in diameter. The mouth, at the upper end of the cylindrical body, is surrounded by petal-like, usually colourful tentacles that bear stinging nematocysts for paralyzing prey such as fishes. Some species eat only microorganisms. Most species remain permanently attached to a hard surface such as a rock or the back of a crab.
sea bass Any of about 400 species (family Serranidae) of carnivorous fishes, most of which inhabit shallow regions of warm and tropical seas. Sea bass have a slender body, small scales, large mouth, and straight- edged or rounded tail. The spiny frontal section and the soft-rayed rear section of the dorsal fin are usually joined but may be separated by a notch. Species range from about 1 in. (3 cm) to 6 ft (1.8 m) long and may weigh 500 lbs (225 kg). About 12 species in the family Moronidae (some¬ times considered a subfamily of Serranidae) inhabit temperate waters. See also BASS.
sea coot See scoter
sea cow or Steller's sea cow Extinct aquatic mammal ( Hydroda- malis gigas) that lived around islands in the Bering Sea. It was discov¬ ered in 1741 and described by a member of Vitus Bering’s expedition. At least 24 ft (7.5 m) long, it had no teeth, a small head, and a broad, hori¬ zontal, forked tail fluke; its dark brown skin was sometimes streaked or spotted with white. It browsed on seaweed. Russian sealers hunted it for food and fur; by 1768 the entire population, estimated at about 5,000, had been exterminated. The term also refers to dugongs and manatees.
sea cucumber Any of 1,100 species of echinoderms constituting the class Holothurioidea, found in all oceans, mostly in shallow water. The soft, cylindrical body is 0.75 in. (2 cm) to 6.5 ft (2 m) long and 0.4-8 in.
(1-20 cm) thick. It is usually dull, dark, and often warty. The internal skeleton consists merely of numerous tiny bits in the skin. Most species have five rows of tube feet extending from mouth to anus. The 10 or more retractile tentacles surrounding the mouth are used for taking food (mud containing nutrients or small aquatic animals) or burrowing. Locomotion is sluglike. See also shellfish.
sea eagle Any of various large fish-eating eagles (especially in the genus Haliaeetus ), of which the best known is the bald eagle. Sea eagles live along rivers, big lakes, and tidewater worldwide except in South America. Some reach over 3 ft (1 m) long. All have an exceptionally large, high-arched beak and bare lower legs. The toes’ undersurfaces are rough¬ ened for grasping slippery prey. They eat mostly carrion but sometimes kill, snatching fish from the water surface and often robbing their chief competitor, the osprey. Asian species include the gray-headed, or greater, fishing eagle and the lesser fishing eagle.
sea fan Any of about 500 coral species (genus Gorgonia) especially abundant in shallow waters along the Atlantic coasts of Florida, Bermuda, and the West Indies. Polyps grow colonially in a flat, fanlike pattern.
Each polyp has some multiple of six tentacles, which it spreads out to form a plankton-catching net. An internal skeleton supports all branches of the colony. The living tissues (often red, yellow, or orange) entirely cover the skeleton. The fan¬ shaped colonies usually grow across the current, increasing their ability to ensnare prey. All species grow to about 2 ft (60 cm) high.
sea horse Any of about 24 species (family Syngnathidae) of fishes that usually live along warm seashores, clinging to plants with their forward- curled, prehensile tail. Species range from 1.5 to 12 in. (4-30 cm) long.
Sea horses have bony rings instead of scales, and their eyes can move independently. They swim upright, propelling themselves horizontally with their fins and vertically with their swim bladder. They catch small organisms by sucking them quickly into their small mouths. The female deposits her eggs into a brood pouch beneath the male’s tail, and the male expels the newly hatched young.
sea ice Ice formed from frozen sea¬ water in polar regions. Most sea ice occurs as pack ice, which drifts across the ocean surface; other types of sea ice include fast ice, which is attached to coasts and sometimes the seafloor or between grounded ice¬ bergs, and marine ice, which forms at the bottom of ice shelves in Ant¬ arctica. The sea ice of the Northern Hemisphere covers about 3 million sq mi (8 million sq km) in September and about 6 million sq mi (15 mil¬ lion sq km) in March. Sea ice in the Southern Hemisphere ranges from about 1.5 million sq mi (4 million sq km) in February to about 8 million sq mi (20 million sq km) in September.
sea lavender Any of about 300 species of chiefly perennial herbaceous plants that make up the genus Limonium of the family Plumbaginaceae, especially L. vulgare. Bearing small flowers in dense spikes, L. vulgare grows in large tracts that sometimes turn acres lilac-coloured in late sum¬ mer. The flower spikes of this and other sea lavenders are often used in dry-flower arrangements for their lasting qualities and permanent colours.
sea leopard See leopard seal
sea level Position of the air-sea boundary, to which all terrestrial eleva¬ tions and submarine depths are referred. The sea level at any location changes constantly with changes in tides, atmospheric pressure, and wind
Scythian gold belt buckle with turquoise inlay, from Siberia; in the Hermitage,
St. Petersburg
NOVOSTI PRESS AGENCY
Sea anemone, Tealia
M. WOODBRIDGE WILLIAMS
Sea fan
DOUGLAS FAULKNER
Sea horse (Hippocampus erectus).
DES BARTLETT-BRUCE COLEMAN LTD.
© 2006 Encyclopaedia Britannica, Inc.
1710 I sea lion ► seal
conditions. Longer-term changes are influenced by changes in the Earth’s climates. Consequently, the level is better defined as mean sea level, the height of the sea surface averaged over all stages of the tide over a long period of time.
sea lion Any of five species (family Otariidae) of eared seals found along coasts on both sides of the Pacific, from Alaska to Australia. Sea lions have short, coarse hair that lacks a distinct undercoat. The males of all but the California sea lion have a mane. Sea lions feed principally on fish, squid, and octopus. They breed in large herds; males establish a harem of 3-20 females. The California sea lion ( Zalophus califomianus ) is the trained seal of circuses and zoos. Males of the various species range from 8 to 11 ft (2.5-3.3 m) long and weigh 600-2,200 lbs (270-1,000 kg).
sea otter or great sea otter Rare, completely marine otter ( Enhy- dm lutris) of the northern Pacific, usually found in kelp beds. Floating on its back, it opens mollusks by smashing them on a stone balanced on its chest. The large hind feet are broad and flipperlike. It is 40-65 in. (100- 160 cm) long and weighs 35-90 lbs (16-40 kg). The thick lustrous coat is reddish to dark brown. By 1910 it had been hunted almost to extinc¬ tion for its fur; now fully protected, it is gradually increasing in numbers.
sea parrot See puffin
Sea People Any of the groups of aggressive seafarers who invaded eastern Anatolia, Syria, Palestine, Cyprus, and Egypt toward the end of the Bronze Age. They were especially active in the 13th century bc. Though the extent and origin of the upheavals remain uncertain, Sea Peoples are believed responsible for the destruction of old powers such as the Hittite empire. The Egyptians waged two wars against them (1236-23 bc and c. 1198-66). The only major tribe to settle permanently in Palestine were the Peleset (i.e., Philistines).
sea power Means by which a nation extends its military power onto the seas. Measured in terms of a nation’s capacity to use the seas in defi¬ ance of rivals, it consists of combat vessels and weapons, auxiliary craft, commercial shipping, bases, and trained personnel. It includes aircraft based on carriers or used in support of shipping. Its main purpose is to protect friendly shipping from enemy attack and to destroy or hinder the enemy’s shipping. It may also be used to enforce a blockade. Finally, naval forces have been used to bombard land targets from the sea. The aircraft carrier added a new dimension to this capability, as did the missile-firing nuclear submarine. The classic exposition of the role of sea power as the basis of national greatness is Alfred Thayer Mahan’s The Influence of Sea Power upon History (1890).