Demand for body parts — driven by the alternative medicine and traditional Chinese medicine industries — have severely threatened giant manta rays, whose populations have declined globally by about one-third in recent years.

The problem has become so concerning to marine biologists and conservationists that the Australian government recently enacted a law protecting the giant ray as a migratory species and making it a crime to capture, kill, or move the animals from Australian waters.

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While overfishing the world's oceans has been a concern for years, the decline in manta rays has little to do with demand for their meat. According to an article in the Sydney Morning Herald,

An investigation last year found the main driver of the manta ray's decline is rapidly increasing demand from Chinese and other markets for gill rakers — thin filaments that rays use to filter food from water — to be dried and boiled as medicines. The group's report found gill rakers were fetching on average $251 a kilogram in Guangzhou in southern China, where 99 percent of the world's product is sold. Targeted fishing of rays occurs predominantly in India, Sri Lanka, Indonesia, Peru and China. The report says local traders are spruiking gill rakers as a way to boost the immune system, while others claim it can treat ailments like chickenpox and even cancer.

The threat is made worse by several factors, including the giant manta ray's slow reproductive cycle and by China's strong economy (more people are now able to afford these pricey body parts).

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And it's not just manta rays; many other animals face similar threats around the world. In Africa, several species of rhinos have been driven to near-extinction because of demand for their horns, which are ground up and used in traditional Chinese medicine, claimed to do anything from act as an aphrodisiac to cure cancer. Tigers have also been slaughtered by the thousands, their bones and claws used in dubious alternative medical treatments.

The real tragedy is that these animals are being killed for myths and lies. If manta ray gill rakers, white rhino horns, tiger bones, bear claws and other body parts could actually cure cancer and other diseases, scientists would be studying them to isolate the active ingredients — without further endangering wild animals.

But they don't work; these animals, and many others, are being driven toward extinction not because of some special, magical properties of their bodies, but because of human ignorance and superstition.

Image: Giant manta ray. Credit: Getty Images