blue-green algae, popular name for those microorganisms that are now more properly called cyanobacteria.

blue-eyed grass: see iris.

blue whale, a baleen whale, Balaenoptera musculus. Also called the sulphur-bottom whale and Sibbald's rorqual, it is the largest animal that has ever lived. Blue whales have been known to reach a length of 100 ft (30.5 m) and to weigh as much as 120 tons; average length is about 75 ft (23 m). The blue whale is slate blue in color and has a dorsal fin. It is toothless and has fringed baleen, or whalebone, plates in its mouth, which act as a food strainer. As water is expelled from the whale's mouth, plankton is trapped behind the strainer. The neck of the blue whale has 80 to 100 conspicuous furrows called ventral grooves, which alternately expand and contract as the animal takes in and expels water. The blue whale is cosmopolitan in distribution. In summer it inhabits polar seas, feeding in the water of melting icepacks; in winter it migrates to warmer latitudes, occasionally reaching the equator. Mating occurs at the end of winter, with a single calf born every second or third year, after a gestation period of 10 to 11 months. The calf is nursed for 6 months and reaches puberty in about 3 years. Blue whales may live 100 years or more. Because of extensive whaling, their numbers have been reduced from an estimated 400,000 to about 12,000, and they are listed as endangered. They are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Cetacea, family Balaenopteridae.

blue vitriol, the pentahydrate of cupric sulfate.

blue shift or blueshift, in astronomy, the systematic displacement of individual lines in the spectrum of a celestial object toward the blue, or shorter wavelength, end of the visible spectrum. The amount of displacement is a function of the object's relative velocity toward the observer. Most observed blue shifts are the result of the Doppler effect. The blue shift is the opposite of the red shift. Blue shifted celestial bodies are quite rare. Of the billions of known galaxies, only about 100, including the Andromeda galaxy, are blue shifted.

blue laws, legislation regulating public and private conduct, especially laws relating to Sabbath observance. The term was originally applied to the 17th-century laws of the theocratic New Haven colony, and appears to originate in A General History of Connecticut (London, 1781), by the Loyalist Anglican clergyman Samuel A. Peters, who had lived in Hebron, Conn. New Haven and other Puritan colonies of New England had rigid laws prohibiting Sabbath breaking, breaches in family discipline, drunkenness, and excesses in dress. Although such legislation had its origins in European Sabbatarian and sumptuary laws, the term "blue laws" is usually applied only to American legislation. With the dissolution of the Puritan theocracies after the American Revolution, blue laws declined; many of them lay forgotten in state statute books only to be revived much later. The growth of the prohibition movement in the 19th cent. and early 20th cent. brought with it other laws regulating private conduct. Many states forbade the sale of cigarettes, and laws prohibited secular amusements as well as all unnecessary work on Sunday; provision was made for strict local censorship of books, plays, films and other means of instruction and entertainment. Although much of this legislation has been softened if not repealed, there are still many areas and communities in the United States, especially those where religious fundamentalism is strong, that retain blue laws. The Supreme Court has upheld Sunday closing laws ruling that such laws do not interfere with the free exercise of religion and do not constitute the establishment of a state religion.

blue jay, common name for a familiar bird (Cyanocitta cristata) of central and E North America, allied to the crow, the raven, and the magpie, belonging to the family Corvidae. Almost a foot (30 cm) long, it is handsome and conspicuous. Its upper parts, including the crest, are grayish violet blue. The wings and tail are bright blue with black and white markings, the neck is collared with black, and the under parts are gray and white. Except during the nesting season it has a raucous cry with hawklike and other imitative sounds. Some winter in their northern range, but many travel south. They feed chiefly on large insects, seeds, and nuts (especially acorns and beechnuts); they also eat eggs and nestlings. When the female blue jay is incubating, she is fed by the male. Blue jays are classified in the phylum Chordata, subphylum Vertebrata, class Aves, order Passeriformes, family Corvidae.

blue crab, common name for a crustacean, Callinectes sapidus, found on the S Atlantic and Gulf coasts of North America. The blue crab is a member of the family of swimming crabs known as the Portunidae and is characterized by a broad, semitriangular carapace (shell) covering the thorax, by a narrow abdomen tucked under its body, and by five pairs of appendages called pereiopods, of which the first two bear large claws (chelae) and the last two are flattened paddles modified for swimming. It is the most common edible crab of the Atlantic coast, and several million pounds are fished commercially by trapping or trawling each year. It is sold both as the hard-shell variety and as the familiar delicacy known as the soft-shelled crab. In the hard-shell form, the crab is in an intermolt phase (between molts) and the exoskeleton is fully hardened (sclerotized). In its soft-shell stage, the crab is in the phase just after the molt but before the exoskeleton has hardened. Since, in nature, the crab retires to secluded areas at the time of the molt and is thus difficult to collect, commercial fishermen collect the crabs at the so-called peeler stage, which occurs two to three days before the molt. The crabs are then held in pens, on floats in the water, until just after the molt, when they are marketable. The ovaries of the female begin to develop only after mating has taken place. The female carries the young under her abdomen until they hatch as tiny larvae, which are only 1/25 in. (0.1 cm) long. The crabs molt many times and grow to 7 in. (17.8 cm) in about 200 days. Blue crabs are classified in the phylum Arthropoda, subphylum Crustacea, class Malacostraca, order Decapoda, family Portunidae.

blue baby, infant born with a congenital heart defect that causes a bluish coloration of the skin as a result of cyanosis (deoxygenated blood). The color is most noticeable around the lips and at the tips of the fingers and toes. The cyanotic condition occurs when a large portion of the venous blood bypasses the lungs. Normally, deoxygenated blood from the veins is pumped from the right side of the heart to the lungs, where it is oxygenated (see circulatory system). In some blue babies, the pulmonary artery is too narrow to allow sufficient blood to pass into the lungs for oxygenation. Surgical correction of the defect is usually required and is usually successful. An incompatibility of fetal and maternal blood types may also cause a bluish coloration in newborn infants, a condition that results when red blood cells in the infant's blood are destroyed by antibodies in the mother's blood (see Rh factor). Sophisticated knowledge of blood types has made this condition increasingly rare.

Russian Blue cat: see cat.

Prussian blue, pigment widely used for laundry bluing, in dyeing compounds, and in the manufacture of inks and paints. Several varieties are known, one of which consists of the chemical compound ferric ferrocyanide.

Kerry blue terrier, breed of large, sturdy terrier perfected in Ireland more than 100 years ago. It stands from 17 to 19 in. (43.2-48.3 cm) high at the shoulder and weighs from 30 to 40 lb (13.6-18.2 kg). Its dense coat is soft and wavy, never harsh, and may be any shade of blue-gray or gray-blue. A truly all-purpose working terrier, the Kerry blue was used to hunt small game, destroy vermin, retrieve on land and water, and herd sheep and cattle. Today it is a popular house pet and show competitor. See dog.

Blue Ridge, eastern range of the Appalachian Mts., extending south from S Pa. to N Ga.; highest mountains in the E United States. Mt. Mitchell, 6,684 ft (2,037 m) high, is the tallest peak. Beginning with a narrow ridge in the north, c.10 mi (16 km) wide, the range broadens toward the south, reaching a maximum width of 70 mi (113 km) in North Carolina. Receiving much rain, the region is heavily forested; wood is the area's chief resource. The Blue Ridge was a barrier to the pioneers' westward movement. Numerous gaps cross the ridge; the gap at Harpers Ferry, W.Va., was an important railroad traverse. Most of the people of the Blue Ridge live on small farms in sheltered valleys and retain traditional lifestyles and speech. Principal economic activities there include livestock raising, farming, tobacco growing, and lumber production. Commercial apple orchards are found in Virginia, Maryland, and Pennsylvania. The Blue Ridge is a major East Coast recreation area noted for its resorts and scenery. The Appalachian Trail winds atop the range. Skyline Drive, Va., following the crest of the Blue Ridge in Shenandoah National Park, has many roadside lookouts. The Blue Ridge Parkway (see National Parks and Monuments, table), designed especially for motor recreation, links the Shenandoah and Great Smoky Mts. national parks.

Blue Rider: see Blaue Reiter, der.

Blue Nile, Arab. Al Bahr al Azraq, river, c.1,000 mi (1,600 km) long, the chief headstream of the Nile, rising in Lake Tana, NW Ethiopia, at an altitude of c.6,000 ft (1,800 m). It flows generally S from the Lake Tana region, then W across Ethiopia, and finally NW into Sudan. At Khartoum the Blue Nile merges with the White Nile to form the Nile proper. The flow of the Blue Nile reaches maximum volume in the rainy season (from June to September), when it supplies about two thirds of the water of the Nile proper. The Blue Nile used to cause the annual Nile flood before the completion in 1970 of the Aswan High Dam (see under Aswan) in Egypt. In Ethiopia the Blue Nile, also known there as the Abbai, flows in a deep gorge and receives many tributaries. There are dams on the Blue Nile at Roseires and Sennar in Sudan; the latter is used to irrigate the Al Gezira region.

Blue Mountains, region of New South Wales, SE Australia. Located W of Sydney, this elevation is actually a plateau forming part of the Great Dividing Range.

Blue Mountains, uplifted, eroded part of the Columbia Plateau, c.6,500 ft (1,980 m) high, NE Oreg. and SE Wash. Lava flows cover much of the surface. The upper, wooded slopes are used for lumbering. Recreation and livestock grazing are the mountains' principal economic uses. Rock Creek Butte, 9,105 ft (2,775 m) high, is the highest point in the Blue Mts. The Blue Mountains were a major physical obstacle for those who once traveled the Oregon Trail.

Blue Island, city (1990 pop. 21,203), Cook co., NE Ill., a residential and industrial suburb of Chicago, on the Little Calumet River; inc. 1843. It has oil refineries, railroad yards and shops, canneries, and plants that manufacture steel products, plastics, fluorescent ballasts, electronic equipment, and chemicals.

Blue Cross plans: see health insurance.

or blue-green algae

Any of a large group of prokaryotic, mostly photosynthetic organisms. Though classified as bacteria, they resemble the eukaryotic algae in many ways, including some physical characteristics and ecological niches, and were at one time treated as algae. They contain certain pigments, which, with their chlorophyll, often give them a blue-green colour, though many species are actually green, brown, yellow, black, or red. They are common in soil and in both salt and fresh water, and they can grow over a wide range of temperatures, from Antarctic lakes under several metres of ice to Yellowstone National Park's hot springs in the U.S. Cyanobacteria are often among the first species to colonize bare rock and soil. Some are capable of nitrogen fixation; others contain pigments that enable them to produce free oxygen as a by-product of photosynthesis. Under proper conditions (including pollution by nitrogen wastes) they can reproduce explosively, forming dense concentrations called blooms, usually coloured an opaque green. Cyanobacteria played a large role in raising the level of free oxygen in the atmosphere of early Earth.

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Mottled, blue-gray baleen whale (Balaenoptera musculus), also called sulfur-bottom whale because of the yellowish diatoms on some individuals. The largest of all animals, the blue whale reaches a maximum length of about 100 ft (30 m) and a maximum weight of 150 tons (136,000 kg). It is found alone or in small groups in all oceans. In summer it feeds on krill in polar waters, and in winter it moves toward the equator to breed. It was once the most important of the commercially hunted baleen whales, and its populations were greatly reduced. Listed as an endangered species, it is now protected.

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U.S. statute regulating work, commerce, and amusements on Sundays. The name is said to derive from a list of Sabbath regulations published (on blue paper or in blue wrappers) in New Haven, Conn., in 1781. Throughout colonial New England such laws regulated morals and conduct. Most lapsed after the American Revolution, but some, such as prohibitions against the Sunday sale of alcoholic beverages, remain on the books in some areas.

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or blue ground

Dark, heavy, often fragmented igneous rock that may contain diamonds in the rock matrix. Kimberlite is a mica peridotite, an ultrabasic rock type with a complex and often highly altered mineral composition. It occurs in the Kimberley district of South Africa and the Kimberley and Lake Argyle regions of Australia, as well as near Ithaca, N.Y.

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Any member of a genus (Callinectes) of decapods, particularly C. sapidus and C. hastatus, common edible crabs of the western Atlantic coast prized as delicacies. Their usual habitats are muddy shores, bays, and estuaries. The blue crab shell, greenish on top and dingy white below, is about 3 in. (15–18 cm) long. The legs are bluish. The chelae, or pincers, are large and somewhat unequal in size, and the fifth pair of legs is flattened for swimming. Blue crabs are scavengers.

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Any member of the widely occurring lepidopteran family Lycaenidae. Adults, sometimes known as gossamer-winged butterflies, are small and delicate, with a wingspan of 0.75–1.5 in. (18–38 mm). Blues are rapid fliers, and most species have iridescent wings. Larvae are short, broad, and sluglike. Some species secrete honeydew, a sweet by-product of digestion that attracts ants, which stroke the larvae with their legs to stimulate honeydew secretion.

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or blue asbestos

Gray-blue to green, highly fibrous (asbestiform) form of the amphibole mineral riebeckite. It has higher tensile strength than chrysotile asbestos. The major commercial source is South Africa, where it occurs in Precambrian banded-iron formations; it is also found in Australia and Bolivia.

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or Blue Ridge Mountains

Section of the Appalachian Mountains, eastern U.S. The range extends southward from Carlisle, Pa., through parts of Maryland, Virginia, North Carolina, and South Carolina to Mt. Oglethorpe in Georgia. The highest peaks are in the Black Mountains of North Carolina; the average elevation is 2,000–4,000 ft (600–1,200 m). The scenic Blue Ridge Parkway, established in 1936 and administered by the National Park Service, runs 469 mi (755 km) along the crest.

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Mountain range, eastern Jamaica. It extends from north of Kingston eastward 30 mi (50 km) to the Caribbean Sea. Its highest point is Blue Mountain Peak, at 7,388 ft (2,252 m). It experiences heavy rain and widely divergent temperatures. Blue Mountain coffee is famous for its excellent quality.

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