Nov 122009
photo provided courtesy of prilfish on Flickr Creative CommonsHometropical and some temperate seas
Nichelarge filter feeder
Lengthbetween 13 and 23 feet
Weightup to 3,500 pounds
Statusvulnerable to extinction
Threatsdepletion of plankton stocks

Silhouetted against the depths of the blue sea, the manta ray seems to live up to its other name, “devil fish.” Two flap-like lobes project from this massive shark relative’s head, giving the appearance of the horned evil one. The slow flapping of its massive “wings” even suggest something cloaked and sinister. However, as the manta ray and thousands of other organisms in the ocean demonstrate, appearances can be utterly deceiving.

Although it shares family relations with more formidable stingrays and killer sharks, the manta ray is harmless to humans. Like the massive whale shark and the large baleen whales, this largest of all rays feeds almost exclusively on the tiniest of creatures in the oceans. This lifestyle has paid big dividends for the manta, allowing it to grow to truly awesome size. A full-grown adult weighs up to 3,500 pounds and its “wingspan” can reach 20 feet across. These modified pectoral fins flap up and down, allowing the manta ray to cruise gracefully through the water like a huge undersea butterfly.

Unlike other rays, the manta ray’s mouth is located at the front of its body rather than the bottom. This allows it to funnel anything small enough into its gaping mouth as it swims constantly through the oceans. Whale sharks share a similar adaptation. While other sharks have mouths under their noses, whale shark mouths are located at the ends of their mouths for the same feeding purpose. After the manta sweeps water into its mouth with its lobes, it filters plankton out of the water with special comb-like rakers inside its gills. Sea water passes out through the animal’s gills, allowing it to feed constantly while swimming.

Unlike the other large filter feeders of the ocean, the manta ray is still vulnerable to large predators like sharks and killer whales. Using its powerful fins, it can accelerate in bursts of speed and even leap out of the water to shake assailants. Mantas are generally solitary animals, but will occasionally come together, especially in rich feeding shoals of plankton and schools of small fish. Females give birth to one or two live young every year, with each infant an impressive 4 feet across.

While manta rays are faring comparably better than many of their shark cousins, it is unclear if they will continue to cheat extinction in the coming years. In particular, ocean acidification exacerbated by climate change could have a drastic impact on the manta’s primary food stocks. Built of brittle calcium skeletons, microscopic plankton will literally dissolve if too much carbon is absorbed the the oceans. Before an uncertain future, only time will tell how the graceful and gentle manta ray will cope with a rapidly changing world.

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