Rays

雪儿 · 发表于: 2011-7-8 11:25:22

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Spotted Eagle Rays

Photograph by Paul Sutherland, National Geographic

A school of spotted eagle rays glides gracefully through the island-speckled waters of the Maldives. The rays are often seen gathering in groups near the surface, “flying” through the water by flapping their pectoral fins and sometimes even leaping porpoise-like into the air. The ray’s dorsal side, invisible in this image, is covered with a signature pattern of vivid spots.

雪儿 · 发表于: 2011-7-8 11:25:36

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Manta Ray

Photograph by Michel Braunstein, My Shot

Each year lunar tides and Indian Ocean monsoon currents combine to drive plankton and tropical krill into confined bays around the islands of the Maldives. These protein-packed waters invite large concentrations of manta rays to an all-you-can-eat buffet. Despite their large size, with wingspans stretching up to 12 feet (3.6 meters), as many as 200 mantas may pack a football field-sized bay during these feeding frenzies.

雪儿 · 发表于: 2011-7-8 11:25:49

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Stingray

Photograph by Michel Braunstein, My Shot

Stingrays often rest on the seafloor, sometimes partially buried in the sand and color-camouflaged from predators like sharks. The ray also deters would-be attackers with a sharp, venomous tail barb. The barb can deliver a lethal blow even to humans, but incidents are extremely rare. Stingrays are fairly docile and typically strike only when provoked.

雪儿 · 发表于: 2011-7-8 11:26:00

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Manta Ray and Wrasse

Photograph by David Doubilet, National Geographic

Manta rays regularly visit “cleaning stations” where small wrasse fish clean them of parasites.

It was recently discovered that mantas, found throughout the world’s tropical and semitropical waters, are actually at least two distinct species—the smaller mantas familiar to divers and their larger, more reclusive relatives, which migrate long distances in the open sea. Unlike stingrays, manta rays do not have venomous tail barbs.

雪儿 · 发表于: 2011-7-8 11:26:10

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Stingrays

Photograph by David Doubilet, National Geographic

Two stingrays cruise through crystal-clear waters near Grand Cayman. Like their close relatives the sharks, the 200-odd species of stingrays are boneless fish that boast skeletons made of tough tissue called cartilage. Some stingrays are bottom feeders and dine on crabs, clams, shrimp, and worms. Other species, like the devil rays, feed on plankton strained from ocean waters.

雪儿 · 发表于: 2011-7-8 11:26:27

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Cownose Ray

Photograph by Mike Theiss, National Geographic

A cownose ray shows off its good side in an exhibit tank at Orlando’s SeaWorld park. The species takes its name from the shape of its rostrum, where the pectoral fins split into two lobes separated by a center crease—creating a feature rather like a bovine nose. Though ocean waters are their primary habitat, these rays adapt well to captivity and, in the wild, can deal with the shifting salinities of estuary and wetland waters.

雪儿 · 发表于: 2011-7-8 11:27:43

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Stingray Mouth

Photograph by Jason Edwards, National Geographic

The stingray’s mouth is found on the belly side of its flat body, an ideal location for these bottom-loving animals to devour clams, mussels, oysters, worms, and other seafloor fare. The ray’s eyes are located topside, but are believed to be less important for finding food than electrical sensory organs surrounding the mouth. These organs, called ampullae of Lorenzini, pick up the electrical charges naturally emitted by prey.

雪儿 · 发表于: 2011-7-8 11:28:40

Electric Ray

Photograph by David Fleetham/Visuals Unlimited, Inc./Getty Images

Electric rays can unleash a powerful electric current to stun their prey or shock would-be predators into choosing another victim. Some large species, like the Atlantic torpedo, can generate an incredible 220-volt blast. The kidney-shaped organs that produce electricity can be seen on either side of the ray’s head. Divers are advised to give these rays a wide berth—some species can be confrontational.

雪儿 · 发表于: 2011-7-8 11:29:46

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Pacific Cownose Rays

Photograph by Paul Souders/WorldFoto/Getty Images

Like their bovine namesakes, Pacific cownose rays gather in a herd. This species prefers to stay near reefs or sandy shallows where they dig crustaceans and mollusks out of the substrate.

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