Another video is circling in my feed, and so another inspiration for a This Week in Zoology was born. Like the last one, this one is also beautiful to watch. Also like the last one, it seems to be sparking a question: what are those silly rays doing?
Those are manta rays, seemingly doing a series of belly flops. And no, that’s not because they lose all grace and coordination in the air, they are actually belly flopping on purpose.
First things first, manta rays are massive. Given the lack of any other object in the video that one could use for scale this is not immediately obvious in the video. So, here’s a picture of a manta ray swimming alongside a person
Rays are, essentially, flat sharks. Both are in the class Chondrichthyes, which means that they do not have bones, but rather their skeletons are made of cartilage. Manta rays are not aggressive, they do not have stings, but are simply content to slowly swim around, filter feeding in the water, and occasionally jumping out and doing a belly flop, a behavior known as “flying”.
So, why do they do this?
Because floating along in the ocean can get dirty. Dead skin, parasites, and other nasty business will tend to accumulate on your body. Therefore, the rays will jump into the air as high as they can and then smack into the surface of the water, to dislodge all the unwanted stuff.
Essentially, that video caught the rays during their exfoliation routine.
Manta rays are not the only rays that do this. A few years ago, a woman in Florida was killed by a 75-pound eagle ray. Having happened relatively soon after Steve Irwin’s death, there was a general panic about it: oh noes, are rays now on the list of super dangerous creatures that we need to fear?
Alas, no. The woman in question was sunbathing on a boat, and the ray jumped out of the water, hoping to belly flop and exfoliate, and instead it belly flopped right on top of the human that happened to be in its way. They both died in the process. It was an incredible coincidence and just a case of very, very bad luck.
So, don’t be afraid of rays just because they happen to share a class with sharks! As a matter of fact, you shouldn’t really be afraid of sharks either, but that will be for another Week in Zoology.