Devil Fish: What's In A Name?
A pack of wolves, a rabble of gnats, a murder of crows, a flock of birds, a tower of giraffes, a stand of trees, a quiver of cobras, a school of fish, an unkindness of ravens (Was Poe in on that one?), an army of frogs, a bloat of hippopotami, a prickle of porcupines, a shiver of sharks, a bale of turtles, a parliament of owls, a cackle of hyenas, a fever of stingrays, and I could go on. All of these are officially recognized names for groups of organisms. And I enjoy using them. They seem to convey succinctly the essence of these animals when they get together in mass, at least from our human perspective. But, what to call thousands of pygmy mobula rays (Mobula munkiana), when they appear in a calm bay beside your anchored boat just north of Cabo San Lucas (where, by-the-way, one can find a syphilis of spring-breakers)? After experiencing these small manta-like rays in just this setting we have some ideas, but simply cannot settle on just one name. I’ll show you why in a bit, but first, their identity needs a bit of clarity.
Mobula is a genus of ray that include several species, from the famous, giant oceanic manta ray (Mobula birostris) to the more diminutive, but otherwise very similar in appearance, pygmy mobula rays who we sometimes experience as they migrate and gather together up and down the Sea of Cortez. Almost all mobula rays lack stingers on their whip-like tails and are gentle filter feeders, using a pair of fin projections on their heads to funnel zooplankton into their mouths. It’s their black backs and those devil-horn-like projections which gave all mobula rays the misleading moniker of Devil Fish that resulted in them being feared and often killed by humans historically. It was certainly NOT their behavior. I mean, LOOK at them! (Use the arrow to see the slide show.)
Before experiencing the thousands of mobulas (a raynado?) gathered just south of Cabo Pulmo we’ve also seen a river of them flowing by us just below the surface while we sail. I once swam with and was gently led all the way back exactly to the boat’s ladder by a bronzing (and perhaps an escort) of a dozen mobulas as the rising, golden sun warmed their black-violet backs to metallic bronze. I’ve snorkeled, using just my arms in a splash-free breaststroke, above thousands of them, stacked so deeply I could not see the bottom and extending so far on any side of me that they became an M.C. Escher-esque puzzle of mobula rays. After one of those epic swims that was more like flying, folks on shore asked me if I was afraid, being among all those devil rays like that. After explaining that they’re harmless I tried and likely failed to convey the meditative experience of being part of a transcendence of mobula rays. Yes, that transcendence of rays surrounded me, giving me the exact amount of space that they were giving each other and allowed me to feel I was one with them. I got to look into their big eyes and empathetically felt their healing scars from shark bites and their occasional, fidgety, annoyance at remora fish attached to their under-wings. It was one of those times when I found in my dive mask salt water that did not come from the sea but from my own eyes, having been so deeply changed by a splendor . . . no . . . a grace of mobulas. (Video to come . . . .)
Then there are the times when a cauldron, a blender, or a flurry of mobula rays stirs up the water’s surface and the black tips of their wings (once you’ve seen them in action you can’t really call them fins) poke out and it looks like an armada of rays. We don’t know as much as we’d like about mobula ray behavior, but it does seem that they naturally join in large groups for courting/mating and when there’s a local upwelling of zooplankton. But lest you think all this occasional, local abundance means that these rays as a species are doing A-OK, keep in mind that some of the localized aggregations of animals that we observe (just look up Sandhill Cranes) actually signal the opposite. It could be that habitat and/or food sources are scarce for such an irony of mobulas, and that we’re observing forced gatherings of animals who we’ve inadvertently pushed into a small corner of survival. We know that mobula ray deaths as bycatch in shrimp and other trawling nets make them especially vulnerable to extinction because they have a low fecundity rate. It takes a few years for them to reach sexual maturity and then the females only birth one pup every two to three years! So, who knows? But a plethora of rays observed could ironically signal a dearth of them. Hmm . . . How about a concern of mobulas, then? Or a vulnerability? (You're almost at the video . . . . )
Of course, it’s impossible to look away from an absurdity of mobulas as they leap out of the water to do somersaults, back flips, half gainers, and good old bellyflops. How about a flip-flop, a circus or perhaps a smack of mobbies then? Ask Gizmo on the kayak what he thinks of that and he’ll say they’re a fright of definitive devil fish. Look at the faces of the families celebrating Easter/Semana Santa on the beach and from pangas where all this is happening and it’s clearly a spectacle of mobulas. I think, happily, that we’ll never be able to corner a school of mobula rays with one fixed name. They are too fluid. But theoretical gun to my head, if I had to go with just one name forever that covers all their known and unknown splendor and goofy antics, I think it would be a wonder of mobula rays. (OK, here's the promised video we managed to get in tough conditions. And a big smooches gracias to Paul for all his photos!)