Gently gliding through the waters, rays look peaceful and calming. As close relatives of the sharks, this shows how arbitrarily humans prescribe characteristics to animals. Rays are calm and majestic, sharks are dangerous killers. And then, the very first topic I find during my research is shark abortions. Yes, shark abortions. But let’s start at the beginning.
Rays belong to the slowest-growing and oldest-maturing vertebrates. The popular manta ray can get 50 years old. Their long lifespans make them vulnerable to a lot of things, apparently including abortion.
They can be found all over the world in all kinds of waters. There are species that stick to the coastlines or estuaries while others stay far away from land for the majority of their lives. Others can be found far from and near the shore. Heck, there are even a handful of freshwater ray species. They can be found in tropical waters, arctic waters, and everything in between, in shallow waters and down into the abyss of the ocean depths.
There are four major groups of rays: the Torpediniformes, which include the coffin rays, numbfishes, sleeper rays, and the very cool electric rays, the Rhinopristiformes with the sawfishes, guitarfishes, and other weirdly formed rays, the Rajiformes or skates, and the Myliobatiformes with the stingrays, eagle rays, buterfly rays, and the oh-so-popular mobula or manta rays.
Chapter 1: Saws and guitars?!
The sawfish is so different from other rays that the common name for it is often carpenter shark even though it is definitely a ray. But who can blame people? We’ve been trained to associate sharks with rows and rows of teeth, dangerous killers, full-on jaws, while media has told us that rays are calm and magical or mystical. Who would lump a creature with a saw as a nose into this group?
Nature published an article a few years back with the title “Humans push a hulking fish with a chainsaw nose toward oblivion,” calling them ‘strange-looking’ in the subtitle. And that’s how far non-rich people get with articles on Nature because instead of sharing knowledge, we put it behind paywalls and massive subscriptions. Did you know that researchers often have to pay to get published in these kinds magazines and then don’t even get a copy for themselves? But that’s a topic for another day.
Back to our weird-looking friends. Sawfishes are especially cool, because they are ovoviviparous, meaning that they bear live young. This isn’t unusual for rays, as we’ll see in a bit. And while those saws are obviously not actual saws, it still looks more than weird to see a small saw stick out of a mama ray during birth.
But what are those saws? First of, the saw is called a rostrum which is the general name for beaks and similar stiff protrusions from the head. Unsurprisingly, it’s not made for sawing anything. Instead, the sawfishes use that thing to sense electrical fields and as a weapon. They are active predators. If they detect prey, they stab and slash with swings powerful enough to their prey into pieces.
There other other rays in the weird-noses group of the Rhinopristiformes like the guitarfishes and the wedgefishes but none are as weird as the sawfish. Oh, and by the way, there’s an actual shark with a very similar saw-like rostrum. So, the carpenter shark is a ray but the sawshark is a shark. Yay for trivial names, right?
There are only a few species of rays, somewhere between 5 and 7 depending on who you ask but three to five of them are critically endangered and the rest endangered. Well done, humans, well done.
Chapter 2: Electricity in the water
Electric rays were drenched in folklore before humans learned about electricity. They didn’t understand why rays could numb fishers without seeming to touch them. But it wasn’t for lack of trying. There was a dude called Athanaeus who talked a lot about seafood in 200 A.D. and ran experiments on rays to find out where the shocks came from.
By now, we know a lot more. The electricity is generated in cells aptly named electrocytes in a specialized organ, a kind of modified muscle that moves ions, so tiny charged particles, across a membrane to discharge. And much like placing batteries in specific ways increases the strength, torpedo rays, for example, have 45 columns of around 700 of those electrocytes with which they can generate a 20 to 50 volts of electricity.
Remember, the typical US outlet has 110 V and the typical outlet in Europe has 220V. They can give you quite the zap. This zap is used to sting their prey, sometimes even through sand.
Chapter 3: Rays that sting
When we went kayaking in the harbor of Marina del Rey in California, the first thing the instructor taught us was what she called the ‘stingray shuffle.’ You know, these things don’t want to attack you but they probably will if a giant foot steps on them. If you shuffle your way through, they usually just slither away.
Back then, I didn’t even know what to be scared of. I had never heard of Steve Irwin, the so-called Crocodile Hunter who was known for being an idiot by looking for and touchy-touching animals he considered dangerous. Well, the dude apparently died in an accident with a stingray. I have a feeling this wasn’t the stingrays fault…
Stingrays have two or three blades with barbs that they use to stab their prey. But they also pack some pretty painful venom. Lucky for stupid humans, the venom is usually not deadly and just hurts like hell. The barbs seem to be the worst issue, as they face the other way as the blade, so pulling out the blade can lead to pretty significant damage. Don’t pull them out, I guess? Or don’t get stung in the first place. Hmmm…
Speaking of penetration: these rays, like the rest of the rays, do internal fertilization. Males have two claspers which kind of look like weird penises. One of these claspers sits next to each pelvic fin. The female has a cloaca the male enters with the clasper for internal fertilization. Honestly, it looks a lot like human sex.
I bet there would be angry parents complaining if footage of this was shown on public TV. You know, like the recent uproar about TVNZ streaming footage of dolphins mating? People really need to learn to deal with sex.
You and me, baby, ain’t nothing but mammals. So, let’s do it like they do on the Discovery Channel.
— The Bad Touch by Bloodhound Gang
But we weren’t talking about the dire state of how we raise our children and how media has influenced us all. Rays, right, rays.
Chapter 4: Skating around the ocean
Skates look a lot like rays. It can be tough to even figure out what’s right in front of you. There are ways to tell them apart, like the fact that they have short tails (and no stingers or blades or similar weapons), have two lobes on their pelvic fins where rays only have one, and they tend to be smaller. Yes, yes, I know, that last one only helps you if you have both. It’s like learning about mushrooms or plants or animals in general. A lot of the descriptions include comparisons like this that don’t help you at all until you already know what else to look for.
The coolest difference for us, though, is that skates are oviparious, so not life-bearing like the rays. They lay eggs that people call mermaid purses for reasons that I don’t quite follow. Doesn’t look like a purse to me. They are laid in clusters of a couple of dozens and then spend quite a long time developing. For the Little Skate, Leucoraja erinacea, the gestation period takes 22 to 54 weeks depending on the season. The eggs develop much more slowly in winter (roughly 45 weeks on average) than in summer (roughly 25 weeks on average).
There are quite a few different species of skates and other Rajiformes, so we won’t get into more detail here. Instead, let’s move on to our fourth and final group: the Myliobatiformes.
Chapter 5: The gentle giants
The group that gives the rays their reputation of being gentle magical creatures includes the manta and devil rays, eagle rays, and cownose rays.
It’s hard to even decide what to include. The spotted eagle rays with their white or yellow spots on their dark diamond-shaped bodies and fused plates of flattened teeth? The cownose rays with their weird headshape and migration groups that can reach 10,000 rays? The devil rays that dance and jump in large groups, slapping the ocean surface with outstretched bodies like children splashing around a pool?
And then there are the manta rays which used to belong to one group but are now split into the smaller coastal manta and the larger open-ocean-dwelling giant manta.
The giant manta, as the name lets you guess is pretty big. With a weight of up to 2.5 tonnes (5,300 pounds) and wing spans (well, fin spans) of up to 9 meters (30 feet), they definitely aren’t small. Weirdly, much like the bigger whales, these creatures are filter feeders. While most of the rays are predators, these beautiful creatures have learned to filter the ocean water for zooplankton. Their long lifespans and tendency to give birth to only one pub per year, make them pretty vulnerable to just about everything humans throw at them from becoming caught up in nets meant for other fish to harvest for the primarily Asian market where firm but gooey is considered delicious.
Chapter 5: Threats
And with that, we are full circle to talking about ray abortions. While the internet celebrates videos of shark and ray life births, researchers in Australia looked a little more closely at what was happening and realized that most of those videos actually showed abortions. When stressed, sharks and rays abort their pregnancies and dispel the immature babies. How easily this happens depends on the species. Pelagic stingrays seem to be particularly vulnerable and 85% of the females lose their young when captured.
This means that, even if mama is released back into the water, she has lost all the hard work she has put into making, feeding and growing her babies.
Fishers are not educated on this issue, as most people have no clue capture-induced abortions are even a thing. Heck, I studied this shit, and had no clue. I don’t think there are any fishermen watching but just in case: if you accidentally catch a ray or shark and want to release her without risk of losing her babies, the lead researcher Kye Adams recommends that you avoid removing her from the water. Cut the line as close to the mouth as possible, and let her go.
This is probably also my cue to urge for ocean protection again. I agree with Kye that we should be adding more restrictions on fisheries. At the very least, we should stop fishing in nursery grounds of endangered species.
Fuck, if you ask me, I’d stop almost all commercial shipping right this moment. But I know, it’s not that easy.
We can’t let that excuse stop us from yelling for change, though. No, it’s not easy but it is necessary that we change the way we eat, live, and exploit this planet.