Manta Rays

Alex Re

Hello, welcome to On Wildlife. I'm your host, Alex Re. On this podcast, we bring the wild to you. We take you on a journey into the life of a different animal every week. And I guarantee you, you're gonna come out of here knowing more about your favorite animal than you did before.

We're sticking with our ocean theme from last week and heading back into the sea for this episode. And the animal that I'm going to be talking about today is subjectively one of the most majestic creatures on earth. But I'm not alone in this adventure, as I got the chance to sit down with Simon Hilburn who works for the Manta Trust. So, get ready to catch some waves because we're going to talk about one of the gentle giants of the ocean: Manta Rays.

Manta Rays are animals that can be found in oceans all over the world. And they can live in different areas of the ocean as well, like near the coast or out in the deep ocean. They're also closely related to sting rays and Devil Rays. And we're going to talk more about their differences later on in the episode.

The first appearance of a manta ray ancestor was about 20 million years ago. And manta rays are actually related to sharks as well. And just like some sharks, they need to keep swimming in order to survive. They need the oxygen in the water to be constantly running through their gills.

So how do they sleep? Well, it's a trick question, because there's evidence to support the fact that manta rays don't sleep at all. Now, manta rays are really cool animals, and there's a lot more to talk about. So, after the break, you're going to hear my interview with Simon Hilburn.

The person that I want to recognize in this week's episode of notable figures in science is Shen Kuo, who was a Chinese scientist during the Song Dynasty. One of the things that he's most well known for is the dream pool essays, where he wrote about a bunch of different species that hadn't been documented before. While studying these species, he noted the importance of environmentalism. And this was way back around 1000 AD.

And this wasn't the only reason that he was ahead of his time. He was one of the first people to talk about using a compass to determine north and south using the Earth's magnetic field. He also described the invention of something like the printing press, which wouldn't have been invented for another 400 years.

One of the most intriguing things about him was the fact that he often talked about UFOs. He helped with the advancement of civilization in so many different ways. It's crazy to me that he's not a household name. If you want to learn more about Shen Kuo, or this series in general, check out onwildlife.org.

Okay, we're back. So Simon is a marine biologist with the Manta trust. And I wanted to see how he got started with manta rays in the first place.

Simon Hilbourne

I learned to scuba diver at quite a young age and I had a slightly unusual sort of upbringing I lived overseas my whole life. So I learned to scuba dive in Thailand at a young age and then kind of fell in love with tropical reef systems and the and the ocean. I went to university in in Southampton in the UK where it was all cold water stuff. And it wasn't really my thing.

So quite soon moved back overseas to study or work with a an organization studying whalesharks. And then it sort of transitioned over that I started working with the Manta Trust in the Maldives and kind of been here ever since for the last five or six years.

Alex Re

That's really cool. And it's just it's something else when you're looking at like coastal tropical waters, like looking at all the the bursting sea life under there. It's It's amazing.

Simon Hilbourne

Yeah, absolutely. I mean, marine biology is is fascinating. And there's so much interesting stuff. And if I wasn't doing tropical marine biology, I'd probably be doing deep sea ecology because I think that's just so fascinating, so interesting. But I really like to sort of put myself in the field and see what I'm doing and things like that. So yeah, I'm ready. We're gonna be doing that in tropical waters now in cold UK waters. And

Alex Re

Yeah, absolutely. Simon also created an initiative called fish free February. It's really cool, and I'll let him explain it.

Simon Hilbourne

That's a new sort of campaign that I've set up and launched actually as a as a new NGO here in the UK a new charity. And the whole sort of idea came from working with Manta trust and visiting fish markets in Southeast Asia and seeing So number of sharks and rays being landed all the time. And speaking to some of the fishermen some of that, what a lot of that was just all bycatch.

Alex Re

Bycatch is when fishermen catch animals that they're not fishing for. And this could be devastating to a whole population of organisms.

Simon Hilbourne

What they were catching was tuna. And it's been to the fishermen, some of that tuna was actually being exported to Europe and America and places like that. So it kind of made me think, okay, hang on a second. I know that now, because I've been to these fish markets. But all my friends back in the UK who haven't been to a fish markets, they're not gonna have any clue that that sort of stuff's going on.

And, yeah, it just kind of struck me that there's a lot of conversation these days about sustainability and how we can sort of live more sustainable lifestyles and reduce our meat consumption and things like that.

But all of the narrative is around red meat and beef and cattle and destroying rain forests and things like that. And so a little talk about the oceans, but with manta rays, specifically, the the biggest threat to manta rays around the world is from fisheries either targeted fisheries where the fisherman is specifically going out hunting for manta rays or Devil Rays, which is appears to be on the decline is not as common as, which is a good thing.

But there's also a huge amount of bycatch fisheries, that's where the fishing fleets are targeting something else. And then the manta rays are accidentally being caught up in the in the fishing nets or fishing lines, even sometimes with with long lines for some modular species.

Alex Re

That's why it's so important to eat fish sustainably and cut down on our overall seafood consumption. Now, let's talk specifically about manta rays. How do we tell the differences between individuals? Well, Simon's got our answer.

Simon Hilbourne

Basically, each and every manta ray is born with a unique spot pattern on their belly on their on the sort of the ventral surface of the of the manta ray. And they're born with that spot pattern, it's sort of it's a bit dull and faded at birth, but then it sort of becomes more pronounced. And that pattern doesn't change throughout their lifetime. So that's a really easy way for scientists to basically identify these individuals much like a human fingerprint. And then we know who those individuals are based off of that.

Alex Re

So this is a great opportunity for the average person to help scientists out.

Simon Hilbourne

So this works great for our marine researchers around the world because we can go out and take photographs. But we can obviously only be in one place at one time. And we only go out for a 45 minute hour dive or whatever or or one day snorkel or something.

But if you imagine how many tourists are out there, and everyone's got a GoPro these days, everyone's got an underwater camera, you've suddenly got a huge network of people who can start collecting data. So that's what it's really tapping into what we call citizen science. So now everyone's able to collect this sort of data, all you need to do is get a photo of the underside of the valley.

Tell us what day it was what time it was, what dive site, it was, because we needed to know where in the world it was. And we can run that idea against all the other mentors that we've kind of got in our database and find out whether it's a new manta ray that we've never cited before, whether it's one that we've seen in that area, maybe it's been there every year, maybe it's come from another region, and now we've got an Reigate migratory path or or a movement.

Alex Re

That's called the ID, the Manta tracking initiative, and anyone in the world can participate.

Simon Hilbourne

I think it's quite interesting for people as well, I mean, you go out on a dive and you see a shark and a turtle and whatever, you never really know much about that. Whereas if you see a manta ray, and you get an idea, and you send it to us, and if we have seen it before, we might have quite a neat, like interesting backstory that we can tell you about that individual that we've seen every year for the last seven, eight years. We saw it pregnant back in 2018, or they had a shark bite and now that's all completely healed, and it's moved between all these different places. It just makes it more sort of relatable to what you've seen and more connected, which I think's really important.

Alex Re

Now, you're probably wondering what the differences between manta rays and sting race, there's more differences than you think.

Simon Hilbourne

They are all relatively similar. They all fall under the elasmobranchs sort of classifications they are fairly related. But there are major distinctions between Manta and Devil Rays and other sting rays. That the shape of their body they have more of a diamond shaped body than kind of around ring which a lot of sting rays will have sting rays kind of as the name suggests, and Eagle rays and stuff like that have stinging barbs on their tail.

Manta rays don't have any barbs on the tail. So it's it's just the tail and yeah, so that's all completely harmless from that, that point of view. And then they're most closely related to Eagle rays and Cownose rays because they all sort of have a similar body shape and or function, but Eagle rays and Cownose rays are now much more benthic.

They live in the basal feed in the substrate looking for crustaceans and mollusks and stuff like that in the in the sand, whereas mantas and Devil Rays they've evolved to live or pretty much pelagic, so they're swimming around in the water column feeding on plankton up in the water column rather than down on the on the seabed.

Alex Re

So they don't have that Stinger that you would find in stingrays meaning that they're pretty harmless.

Simon Hilbourne

They are very big animals those you definitely want to get in the way of one and accidentally get hit by the wing because it's it's a solid animal.

Alex Re

Oh, wow. Yeah. And I feel like a lot of people if you see him on TV or on a screen, you don't realize how big these animals actually are.

Simon Hilbourne

Yeah, I mean, the big oceanic mantas grow up to sort of six seven meters and wingspan reef mentors for four and a half in some places. So yeah, these 234 times the size of the human, if not more, yeah, getting up to the size of like a minivan almost.

Alex Re

Yeah, that's crazy. Even though they're not dangerous to humans, they still have to eat something and they use structures called gill rakers to catch their prey.

Simon Hilbourne

Manta rays have five pairs of gills gill slits, and inside of those, there's a Gill arch. So 10 tensile structures, and that's where the manta rays can swim around with their mouth wide open the two cephalic fins are sort of the horns on the head of the animal they unfurl and they act as a funnel.

And they scoop in lots and lots of water into their mouth, and then that passes through the gills, the gill slip and the gill plate is able to basically redirect and push the small bits of plankton that the manta rays want to feed or the devries want to feed on into the back of the mouth area where they can then sort of swallow it. So it's used for feeding that they're filter feeders that pack planktonic filter feeders, swimming around when they're feeding with their mouth wide open for long periods of time.

Filtering all this, these tiny like plankton, animals, planktonic animals, kind of the size of a grain of rice, filtering those all out of the water. And they're also used in respiration as well. So like other sharks and rays and stuff.

Alex Re

That's really a crazy adaptation and really cool and I think a lot of those huge animals that you find in the in the ocean are usually the ones that are eating those microscopic plankton.

Simon Hilbourne

Yeah, it is odd how that works, isn't it? I mean, you got the whale sharks in the mega mouths and then even in the in the whales, like the some of the big baleen whales with their, their filter feeders as well. So it's, it's interesting how it works.

Alex Re

And sometimes you'll see that manta rays look like they're flying out of the water. I wanted to know why this is.

Simon Hilbourne

Yeah, it's not entirely understood exactly why it happens. It is fascinating when you see it's, it's such a cool spectacle, especially with the manta rays, because they're such huge animals and to get to a speed where they can propel themselves out of the water is quite quite a feat.

But yeah, they can basically clear themselves completely out of the water and come smashing down some of them like land on their belly, some land on their backs. And we're not entirely sure why this happens. It happens semi regularly over cleaning stations, where the manta rays and visiting a bit of reef to be picked clean up parasites and things like that.

So there's thoughts that there may be breaching to get the itchy parasites and itchy remoras off. So they're trying to dislodge all of those things. There's a possibility. But we also see a lot of breaching just before feeding events, mass feeding events and things like that.

So there's also a potential that it might be some form of communication, possibly also for courtship, maybe to kind of attract me or something to do with that. It's quite hard to to know at the moment.

But then some of the other species of mobiles as well, like the monks devil Ray, in, in the Sea of Cortez in Baja, California and Mexico. They're pretty famous for for jumping, and you get these big schools of Devil Rays and all leaping out of the water kind of at the same time. And these are kind of mini mentors, the little Devil Rays. And it's super cute. So yeah, really fascinating, but we're not entirely sure why it happens. Still, it's still more questions.

Alex Re

Okay, so we know that they're majestic, but are they intelligent,

Simon Hilbourne

As far as fish and things go, they're definitely up there with some of the most intelligent species of fish. They, they have these sort of social behaviors, and they have cooperative feeding behaviors, lots of different feeding strategies, lots of different kind of, yeah, social mechanisms and stuff like that.

We're still in the early days of trying to like figure out whether there's hierarchies between populations. In general manta rays are considered to be solitary animals. So they live alone, and they travel between areas by themselves. But we definitely get aggregations and mantas coming back to the same cleaning stations and gathering in large groups when they're feeding.

And then they sort of start to break off into Yeah, like I said, uncooperative feeding. So we get chained feeding where they're all feeding in a line, one behind each other up and down, and they'll follow a current path or they aspire off into Cyclone feeding. So it's kind of working cooperativity to make the most of the the available food, which is quite a sort of complex behavior.

And, again, we're kind of we're talking about fish here, not not mammals. So it's not dolphins and whales and things like that they're slightly less developed. But as far as fish go, they have one of the largest brain to body size ratios in the world, so of any species in fish. So that also goes to suggest that Yeah, they might have a fair amount of brain capacity.

Alex Re

Just the fact that they're able to work together. So well is a testament to how smart they are.

Simon Hilbourne

You kind of get that vibe as well, when you're in the water with them, there's, there's definitely something going on between those eyes, the manta ray will sort of check you out and swim around you and definitely sort of know that you're there. And there's, there's something going on, and they're inquisitive. So it's super interesting from that side of things as well.

Alex Re

Obviously, these huge animals that eat a lot of food are going to be extremely important to the ecosystems that they live in. Here's Simon For more on that.

Simon Hilbourne

Yes, they paid quite an interesting role. And they often feed in in different areas and then return so sort of offshore areas off from the reef and deeper waters, and then channels and things like that a bit further off the reef. And then they return back to the shallow cleaning reefs.

And that's where they spend their time cleaning. And they basically feed in one area and come back and then compare in another area. And that's basically nutrient transfer from from one ecosystem to another. And one of our affiliate projects down in the Seychelles found out that found that these manta rays were sort of filling this ecological niche that no other species was really doing on the coral reefs of transporting nutrients back from, from from habitats off the reef back into the sort of shallow coastal reefs, which is quite interesting.

And then obviously, from a human perspective, there's huge tourism around these animals, they are such elegant, beautiful animals that people really want to spend a lot of time in the water with. And we'll pay money to to go and see essentially, so having them alive and having sort of healthy populations is important for local communities that rely on tourism.

Alex Re

So they're important to the ecosystems and to the local economy. Unfortunately, they're struggling right now. Simon told me how the average person can help manta rays,

Simon Hilbourne

I think seven of the 10 or 11 species of Manta and Devil Ray, they're now listed as endangered, and all the rest are either vulnerable, or we just don't have enough information about so they're definitely moving in in the wrong direction towards this sort of extinct end of the spectrum, which is is bad news.

But they're also really important for conservation, because they're kind of an iconic species that people can really fall in love with. So you can really connect people to the ocean environment and the marine ecosystems through manta rays, people who maybe wouldn't be as interested otherwise. So it's kind of like that gateway animal that you can kind of get them hooked on marine conservation and saving the oceans, because of this beautiful iconic species.

And then through that, you can kind of hopefully get them to protect the wider ecosystem and all the other fish and animals and, and coral and plants that live in the ecosystem as well. As far as things go for things that people can do, reducing the amount of seafood that we eat, moving towards a more plant based diet, if possible. And yeah, just kind of reduce in general and then choose sustainable options where possible.

In terms of other things that people can do: learn about manta rays, they're fascinating animals, there's lots of cool stuff and share that knowledge with other people tell other people about them. A lot of people don't really know what a manta ray is, or the fact that they're endangered or sort of how majestic they are. And you can also obviously, submit ID photos if you're on holiday anywhere around the world. And you do come across Mantas like we mentioned, you can you can kind of support Manta conservation that way.

And similarly, if you're if you're doing any ecotourism, try to look for an operator that's that has code of conduct and follow some sort of guidelines with Manta interactions because you don't want to be getting too close to them or riding the manta rays or disturbing them in any way. So we want to try and follow sustainable code of conduct.

And then lastly, obviously, a lot of these marine conservation organizations that are nonprofits, charities, and so we rely on public donations and things like that in order for us to continue our work. So yeah, donations and things like that to the marine conservation charities goes a long way and is always well received.

Alex Re

Yeah, definitely. And you brought up a lot of great points and there's so much that we can do to help and when you're helping manta rays, you're, you're helping ecosystems, entire ecosystems and some of the stuff that you mentioned just helps all wildlife which is amazing. So where can we find more information about the Manta trust.

Simon Hilbourne

Yes, we're on. We're on social media. We're on Instagram, Facebook and Twitter. And then our website is www dot Manta trust.org. There's loads of great resources on our website educational stuff about manta rays and their threats and their ecology and things like that.

We've also got a large education section with kids clubs, activities, and things like that. So if anyone has young children and looking for activities to do and want them to be marine themed, we've got lots of games and stuff on there, which is, which is great. And you'll find all the other information about how to support us on air as well, if you do want to adopt a manta ray or anything like that, that can all be found on our website as well.

Alex Re

That's really great. Everybody should definitely go check that out. Simon, thank you so much for coming on. Again. I learned so much and I think everybody's really going to enjoy hearing about manta rays.

Simon Hilbourne

Perfect. Thank you very much, Alex, it was a pleasure.

Alex Re

I really loved hearing about all of Simon's experiences and the projects that he's working on to help manta rays thrive. And luckily, we can do a lot to help them too, by supporting organizations like the Manta trust. You should also check out to other organizations that are helping manta rays in the wild right now. There's Manta Pacific Research Foundation and the Manta Caribbean project.

Thank you so much for coming on this adventure with me as we explored the world of manta rays. You can find the sources that we used for this podcast and links to organizations that we reference at onwildlife.org.

You can also email us with any questions at onwildlife.podcast@gmail.com and you can follow us on Instagram @on_wildlife and on TikTok @onwildlife. Don't forget to tune in next Wednesday for another awesome episode. And that's On Wildlife.

Jess Avellino

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Transcribed by https://otter.ai