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Today on Animal Fact Files we’re discussing butterfly rays. These shark relatives get their common name because they have much wider pectoral fins than the length of their body. These "wing-like" fins are similar to the wings of butterflies. There are about a dozen classified butterfly ray species and they live in tropical and warm temperate waters around the world. They're mostly coastal fishes, living no deeper than 300 feet (100 m) below the waves, however, some take up residence in brackish water river mouths, so they tolerate a wide range of salinity. These are benthic animals, spending their time at the bottom of the water column, often preferring sandy or muddy bottom areas.

Butterfly rays are often colored to match their surroundings, so they come in shades of brown and grey, sometimes sporting spots. With their flat body pressed against the sand, or dug slightly under, they all but disappear. This helps hide them from predators and prey alike. Although butterfly rays can be very large, some reaching up to 6 foot (1.8 m) wingspans and 130 pounds (60 kg) in weight, they're generally considered harmless. They have a short tail and not every species possesses a stinger with which to defend themselves. In most cases, if a human is stung by a butterfly ray, it's not lethal. This is why they employ camouflage to avoid detection.

Large fish, such as sharks, especially great hammerheads who are ray specialists, eat butterfly rays. They're also believed to be taken by marine mammals. In turn, these fish eat smaller fish as well as crustaceans and molluscs dug up from the bottom. Unlike many other ray species, butterfly rays have over 100 sharp teeth in their mouth for grasping and holding prey. This is in contrast to the crushing teeth in other ray species. Butterfly rays also have to contend with gill parasites as a potential threat. These fish can take in water either through their gill slits on their underside or the holes behind their eyes; these are called spiracles.

Female butterfly rays may be even larger than males and sometimes show off a more rounded, blunt snout compared to a male. It's not unusual for the leading edge of their pectoral fins to turn slightly inward, giving them a concave appearance. Often in smaller species or individuals, the skin is smooth, but it can be rougher in larger specimens. Sometimes these rays are targeted by various fishing industries for their flesh. They may be used as food for human consumption or they may be butchered and used as bait for crabbing.

It's likely that butterfly rays live at least a decade if they can avoid these threats and potentially even longer. Members of this group of animals tend to have relatively long lifespans. These fish mate with a male and female embracing one another. The female retains the fertilized eggs inside her while they develop and eventually hatch. The babies are then nourished with uterine proteins until they're born live. A female butterfly ray has two uteruses and the babies are typically split evenly between them. The average litter has four to twelve pups. They're born fully developed and ready to take on the world from birth. In fact, newborn butterfly rays can reach up to a foot (30 cm) in wingspan and over two pounds (900 g) in weight!

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