University of Miami Rosenstiel School of Marine and Atmospheric Science
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Manta Information

Manta rays belong to the Mobulidae family.  They are elasmobranchs, cartilaginous fish, related to sharks and skates.  Their common name “manta” is also their genus name.  There are two species of manta ray, the giant manta ray (Manta birostris) and the smaller reef manta ray (Manta alfredi).  Both rays have a diamond-shaped mantabody, long pectoral fins that are very wing-like and a short whip-like tail.  They have vertically placed gill slits, laterally placed eyes, wide terminal mouths, and come in less tropical colors like chevron and black.  Usually the top of their body is dark, while individuals may be identified by the color patterns underneath them.  When measuring by wing-span, they can grow up to 23 feet.  In addition to the giant manta ray usually being the larger of the two ray species, they also have a caudal thorn and a rough skin appearance.

They are primarily filter feeders who eat mostly zooplankton, as well as euphausiids, copepods, mysids, decapod larvae and shrimp.  There have been cases where small and moderately sized fish have been noted in their diet.  Rays are found worldwide in tropical, subtropical, and temperate waters.  There are often found either offshore in the pelagic ocean or near productive coastlines.  They can dive up to 200 to 450 meters.  They are a migratory species who visit certain regions seasonally based on seasonal upwelling, tidal changes, seawater temperature, zooplankton movement, and mating behavior.  The main predators of the manta ray are sharks, large carnivorous whales, and man.  Their biggest threats by far are from commercial and artisanal fishing and harvesting of their gill rakers for international trade.  Sometimes mantas are specifically targeted, other times they are an unfortunate product of bycatch.  Under the Endangered Species Act, Manta rays are considered threatened.  Many of the areas these rays live in prohibit harvesting, but enforcement may be difficult and targeted fishing still occurs.

Manta rays are a slow growing species that can live to be about 40 to 50 years old.  Population decline is a serious issue because of all the elasmobranchs, manta rays have the lowest fecundity.  Gestation takes a whole year, and giant manta rays only give birth to one pup every two to three years.  It can be difficult to both track and protect manta populations because their small populations are spread sparsely worldwide.  Dispersed populations consist of anywhere between 100 and 1,500 individual rays.  These docile creatures are no threat to humans.  In some areas, manta rays are actually a boost to dive tourism.  Many enjoy watching them glide through the water, and surface tourists may be lucky enough to see them breach the water.  Divers are warned against touching manta rays in the event they accidentally remove some of the ray’s protective mucous layer, causing skin lesions.