Mantas or devil rays are amongst the most fascinating inhabitants of the world’s oceans. So it is surprising that they are also amongst the least known of all the fishes that inhabit the seas. Some species attain a gigantic size, and were once the subject of superstitious fear simply because of their devilish appearance. Only recently mantas have gained the favour of diving tourists, who enjoy their gentle attitude and the sight of their majestic swimming and demeanour. And yet, knowledge of their family tree was messed up into an almost inextricable confusion, and nobody was sure of how many species existed, because, through research spanning over two centuries, ichthyologists the world over had described devil rays with hundreds of different names.
Part of my doctoral work at the Scripps Institution of Oceanography included tidying up this mess. For years I traveled around the world looking up old specimens in the most diverse museum collections, from Harvard to Chennai, from Paris to Cape Town, and from London to San Francisco. In the end, the mountain of names which had been given to species was boiled down to a handful, because too often the same species had been described over and over again, by different people and with different names, without worrying too much whether that species had been described already by someone else.
As it turned out, this painstaking work eventually carried conservation significance because devil rays have become seriously threatened despite they low market value. This is in large part by virtue of the most stupid of reasons: the purported medical properties of the devil rays’ branchial filter plates, which quite recently became fashionable in the Chinese “traditional” medicine.
To limit the damage, devil ray species in October 2016 were listed by CITES, the Convention on International Trade in Endangered Species, and exporting their gill plates to China is no longer an easy business. The practical advantage of a being able to count on a detailed taxonomic knowledge of the various species, in this effort, is obvious.