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ray (in zoology)

ray, extremely flat-bodied cartilaginous marine fish, related to the shark. The pectoral fins of most rays are developed into broad, flat, winglike appendages, attached all along the sides of the head; the animal swims by rippling movements of these wings. Most rays have slender whiplike tails. The eyes and spiracles are located on top of the head, the mouth and the gill slits on the underside. Many rays are bottom dwellers, lying like rugs on the seafloor; others inhabit the upper waters. Bottom-dwelling rays breathe by taking in water through the spiracles, rather than through the mouth as most fishes do, and passing it out through the gills. Rays feed on a variety of smaller animals; the heavy, rounded teeth of most species are adapted to crushing the shells of snails and clams.

Types of Rays

The rays, which form the order Batoidea, are divided into seven families. The largest are the mantas, also called devil rays and devilfish (family Mobulidae). These are top-swimming forms which may weigh up to 3,000 lb (1360 kg), with a width of up to 22 ft (7 m). Unlike most rays, mantas are filter-feeders; the manta uses a pair of horns at the front of the head to drive small prey into its mouth; there the prey is caught in a strainer and swallowed, the water passing out through the manta's gills. Electric rays, or torpedos (family Torpedinidae), have electric organs in their wings that generate electric current, used to immobilize prey and for defense. The current is strong enough to stun humans, and it is said that the ancient Greeks used these fish for shock therapy. Skates (family Rajidae), which are sometimes caught for food, are bottom dwellers; some species have electric organs in their tails. The stingrays, or whiprays (family Dasyatidae), have rows of spines along their tails, which are generally much longer than their bodies. The stingray inflicts wounds by lashing with its tail; the spines contain a poison that causes pain and can be fatal to humans. Most of the eagle rays and bat rays (family Mylobatidae) bear a single poison spine on the tail. The guitarfishes (family Rhinobatidae) are sharklike in form, having well-developed tails used for swimming and smaller pectoral fins than most rays; however, the fins are attached, as in all rays, above the gills, giving these fishes a broad-headed appearance. Sawfishes (family Pristidae) are similar in body form, but have long, flat snouts with a row of toothlike projections on either side. Some species reach a total length of 20 ft (6 m), with snouts 6 ft (1.8 m) long and 1 ft (30 cm) wide. They use these ponderous weapons to slash and impale small fishes and to probe in the mud for burrowing animals. Sawfishes, which are endangered globally, should not be confused with saw sharks, which are true sharks.

Reproduction and Distribution

Fertilization is internal in rays. Most bear live young, but the skates lay flattened, rectangular eggs, enclosed in leathery shells, with tendrils at the corners for anchorage. Empty egg cases of this type are found on beaches and are known as mermaids' purses. Most ray families have a more or less cosmopolitan distribution in tropical and subtropical marine waters; some include temperate or cold-water species. Some rays can live in brackish bays and estuaries, and the sawfish enters freshwater rivers and lakes.

Classification

Rays are classified in the phylum Chordata, subphylum Vertebrata, class Chondrichthyes, subclass Elasmobranchii, order Batoidea.

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ray

ray1 / / • n. 1. each of the lines in which light (and heat) may seem to stream from the sun or any luminous body, or pass through a small opening: a ray of sunlight came through the window. ∎  the straight line in which light or other electromagnetic radiation travels to a given point. ∎  (rays) a specified form of nonluminous radiation: water reflects and intensifies UV rays. ∎  Math. any of a set of straight lines passing through one point. ∎  (rays) inf., sunlight considered in the context of sunbathing: catch some rays on a secluded sandy beach. ∎ fig. an initial or slight indication of a positive or welcome quality in a time of difficulty or trouble: if only I could see some ray of hope. 2. a thing that is arranged radially, in particular: ∎  Bot. (in a composite flowerhead of the daisy family) an array of ray florets arranged radially around the central disc, forming the white part of the flowerhead of a daisy. ∎  (also fin ray) Zool. each of the long, slender bony protuberances supporting the fins of most bony fishes. ∎  Zool. each radial arm of a starfish. • v. [intr.] spread from or as if from a central point: delicate lines rayed out at each corner of her eyes. ∎  [tr.] poetic/lit. radiate (light): the sun rays forth its natural light into the air. PHRASES: ray of sunshine inf. a person or thing that brings happiness into the lives of others.DERIVATIVES: ray·less adj. ( chiefly Bot. ). ray2 • n. a broad, flat marine or freshwater fish (Rajidae and other families) with a cartilaginous skeleton, winglike pectoral fins, and a long slender tail. Many rays have venomous spines or electric organs.

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"ray." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 22 Aug. 2017 <http://www.encyclopedia.com>.

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ray

ray Any of several species of cartilaginous, mostly marine fish related to the skate, shark and chimaera. The ray is flattened dorso-ventrally; its body extends sideways into large, wing-like pectoral fins that are ‘flapped’ while swimming. The tail is narrow, and may be whip-like or bear poisonous spines. Electric (torpedo) rays stun their prey with electrical charges of up to 200 volts. Length: 1.5m (5ft).

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"ray." World Encyclopedia. . Encyclopedia.com. 22 Aug. 2017 <http://www.encyclopedia.com>.

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ray

ray A line of cells that extends radially across secondary phloem and secondary xylem. It is initiated in the vascular cambium and consists mainly of parenchyma cells, although in gymnosperms it may also include tracheids.

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"ray." A Dictionary of Plant Sciences. . Encyclopedia.com. 22 Aug. 2017 <http://www.encyclopedia.com>.

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ray

ray2 edible sea-fish allied to the shark. XIV. — (O)F. raie :- L. raia.

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"ray." The Concise Oxford Dictionary of English Etymology. . Encyclopedia.com. 22 Aug. 2017 <http://www.encyclopedia.com>.

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ray

ray Cartilaginous fish, Raja spp.

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"ray." A Dictionary of Food and Nutrition. . Encyclopedia.com. 22 Aug. 2017 <http://www.encyclopedia.com>.

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ray

ray See RAJIFORMES.

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ray

rayaffray, agley, aka, allay, Angers, A-OK, appellation contrôlée, array, assay, astray, au fait, auto-da-fé, away, aweigh, aye, bay, belay, betray, bey, Bombay, Bordet, boulevardier, bouquet, brae, bray, café au lait, Carné, cassoulet, Cathay, chassé, chevet, chez, chiné, clay, convey, Cray, crème brûlée, crudités, cuvée, cy-pres, day, decay, deejay, dégagé, distinguée, downplay, dray, Dufay, Dushanbe, eh, embay, engagé, essay, everyday, faraway, fay, fey, flay, fray, Frey, fromage frais, gainsay, gay, Gaye, Genet, gilet, glissé, gray, grey, halfway, hay, heigh, hey, hooray, Hubei, Hué, hurray, inveigh, jay, jeunesse dorée, José, Kay, Kaye, Klee, Kray, Lae, lay, lei, Littré, Lough Neagh, lwei, Mae, maguey, Malay, Mallarmé, Mandalay, Marseilles, may, midday, midway, mislay, misplay, Monterrey, Na-Dene, nay, né, née, neigh, Ney, noway, obey, O'Dea, okay, olé, outlay, outplay, outstay, outweigh, oyez, part-way, pay, Pei, per se, pince-nez, play, portray, pray, prey, purvey, qua, Quai d'Orsay, Rae, rangé, ray, re, reflet, relevé, roman-à-clef, Santa Fé, say, sei, Shar Pei, shay, slay, sleigh, sley, spae, spay, Spey, splay, spray, stay, straightaway, straightway, strathspey, stray, Sui, survey, sway, Taipei, Tay, they, today, tokay, Torbay, Tournai, trait, tray, trey, two-way, ukiyo-e, underlay, way, waylay, Wei, weigh, wey, Whangarei, whey, yea

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