Speaker 1: Welcome to Stuff to Blow Your Mind production of iHeartRadio.
Speaker 2: Hey you welcome to Stuff to Blow Your Mind. My
Speaker 2: name is Robert Lamb.
Speaker 3: And I am Joe McCormick, and we're back with part
Speaker 3: three in our series on the genus mobula, the manta rays,
Speaker 3: and the devil rays. In part one of the series,
Speaker 3: we talked about the original inspiration for covering this topic,
Speaker 3: which was that Rob you and your family got to
Speaker 3: see reef manta rays in person while snorkeling in Indonesia
Speaker 3: this summer, which sounds like an amazing experience.
Speaker 2: Yeah. Again, it almost is too much to describe, but yeah,
Speaker 2: we jumped out of the boat. This is after an
Speaker 2: initial snorkeling in another coral rich area, and then they
Speaker 2: took us out to a manta ray cleaning station, which
Speaker 2: we're going to get into in this episode. If you
Speaker 2: don't know what a cleaning station is, you're about you're
Speaker 2: going to find out. It is not like a service station.
Speaker 2: It is not an artificial, human made thing. When I
Speaker 2: don't remember when this was, but the very first time
Speaker 2: I heard about cleaning stations in the water for organisms,
Speaker 2: it made me think, oh, well, they installed a big
Speaker 2: rotating brush in the water and it draws in the
Speaker 2: fish because cleaning stations. Again, we'll get into all the
Speaker 2: details of this. It is a place where if you
Speaker 2: know where the cleaning stations are, then you as divers
Speaker 2: or snorkelers can go there and you have an increased
Speaker 2: chance of seeing the various organisms that make use of it.
Speaker 3: Unfortunately, I had a much bloodier picture in my mind,
Speaker 3: but I think fish and cleaning station. I think of
Speaker 3: like a gutting station where the guys there like ripping
Speaker 3: the guts out of the fishy.
Speaker 2: Cot Well, you know, there's a little bit of that
Speaker 2: sprinkled in. We'll get into it, but yeah, basically, we
Speaker 2: second stop on this snorkeling this morning snorkeling trip that
Speaker 2: we did, and they took us out to a cleaning
Speaker 2: station and we jumped in the water and it was,
Speaker 2: you know, this just reef environment was but it was
Speaker 2: much deeper than we'd been in, a little darker than
Speaker 2: we'd been in. And I sometimes get a little nervous
Speaker 2: when we're talking about like deeper water and bigger things
Speaker 2: in the water. But seeing these large reef mantis going
Speaker 2: about their business doing some loops here and there, even
Speaker 2: it was magical. You just felt absolutely at peace with them.
Speaker 3: So after that. In the first episode, we also talked
Speaker 3: a bit about the history of human interactions with manter
Speaker 3: rays and devil rays. We got into old misconceptions that
Speaker 3: manter rays are threatening to human boats and divers that's
Speaker 3: not true, and relatively new misconceptions that their body parts
Speaker 3: have medicinal value. Of course, both of these false beliefs
Speaker 3: leading to harm to manta and devil ray populations by humans,
Speaker 3: and we also talked about ongoing conservation efforts to protect
Speaker 3: the world's remaining rays. We discussed some basics of manter
Speaker 3: ray biology, including their body design, feeding habits, and their
Speaker 3: tendency to breach the water's surface leaping up in the air.
Speaker 3: In part two of this series, we followed up on
Speaker 3: stories from an older marine biology article that told of
Speaker 3: mantas and devil rays taking hold of the anchor lines
Speaker 3: and mooring lines of a boat and dragging the boats
Speaker 3: out to sea, and we discussed how it seems this
Speaker 3: can happen and sometimes does actually happen, but it's clearly
Speaker 3: not intentional on the part of the manta, and we
Speaker 3: got into some biological reasons that mobulid rays are prone
Speaker 3: to getting tangled in loose lines in the water. We
Speaker 3: also talked about some recommended methods for making mooring lines
Speaker 3: safer for rays. After that we got into mobulid reproduction,
Speaker 3: which is really fascinating the way they engage in internal
Speaker 3: fertilization and viviparity, meaning sort of full body contact, sexual intercourse,
Speaker 3: and live birth respectively, so making them, as in so
Speaker 3: many other ways, kind of superficially resembling of mammals, even
Speaker 3: though they are fish not mammals. And we also got
Speaker 3: into the elaborate fitness displays that males go through in
Speaker 3: these sort of mass chain races before the female finally
Speaker 3: chooses her mate. And today we're here again to talk about.
Speaker 2: More that's right, and the place I'd like to pick
Speaker 2: up is discussing manta rays and their parasites, And there's
Speaker 2: some bleed over here into other mobulate parasite loads as well.
Speaker 2: Some of the information you know applies to devil rays
Speaker 2: and so forth, and a lot and as we've been discussing, like,
Speaker 2: there's a lot more known about the ins and outs
Speaker 2: of reef manta rays as opposed to the oceanic manta rays,
Speaker 2: which are the largest. So you might remember back to
Speaker 2: our episode about the gray whale, and like the basic
Speaker 2: observation that large marine animals often have to deal with
Speaker 2: sizeable parasite loads, or if not actual parasites, then creatures
Speaker 2: engaged in some degree of mutualism either way you slice it,
Speaker 2: large marine organisms tend to attract a fair number of
Speaker 2: hangers on and they become mobile environments for these various organisms.
Speaker 3: In the case of gray whales, am I remembering right,
Speaker 3: that barnacles would tend to attach to the outside of
Speaker 3: the gray whale, Like the gray whale becomes a substrate
Speaker 3: that is useful for the barnacle because they need something
Speaker 3: solid to attach the bottom of their body to. And
Speaker 3: then also by moving through the water, the whale you know,
Speaker 3: brings food to them, essentially allowing water to flow past them.
Speaker 2: Right, And as we discussed in those episodes like there's
Speaker 2: there was on one hand a strong case to be
Speaker 2: made that oh, well, these these the poor whales are
Speaker 2: just covered with these barnacles, like a ship with barnacles
Speaker 2: gaining no benefit from it. But then we also explored
Speaker 2: a hypothesis that proposed that well, actually there are some
Speaker 2: potential benefits to having these barnacles on your body.
Speaker 3: Yeah, the question was do the barnacles form a kind
Speaker 3: of armor of sorts That was not known for sure.
Speaker 3: To be clear, that was like a possibility, but I
Speaker 3: think it was more likely assumed that it is sort
Speaker 3: of a net negative to the whale to have all
Speaker 3: the particles on it.
Speaker 2: Yeah, but this similar conversation often occurs around these discussions
Speaker 2: of symbiosis and mutualism and parasitism, questions about who's getting
Speaker 2: the most out of this relationship, is it unbalanced? To
Speaker 2: what degree is it unbalanced? And you see it go
Speaker 2: various directions where arguments end up being made that what
Speaker 2: is thought of as a parasite might actually have some benefits,
Speaker 2: and you and the opposite something that seems like there's
Speaker 2: a beneficial give and take, and maybe it's a little
Speaker 2: less beneficial than we used to think it was. At
Speaker 2: any rate, it's definitely the case with the manta ray
Speaker 2: that they have a lot of hangers on and they
Speaker 2: vary greatly. Mantas have to contend, for instance, with tiny
Speaker 2: copa pod parasites that get literally everywhere on them. Meanwhile,
Speaker 2: you also have things like harmless juvenile golden travelerfish which
Speaker 2: just ride the pressure wave and alongside the creature, and
Speaker 2: in the same way that sometimes dolphins are seen to
Speaker 2: ride along side ships. But as far as I'm to understand,
Speaker 2: they don't pose any risk or damage to the manta rays.
Speaker 2: And then they split when they're old enough to fin
Speaker 2: for themselves, and then you have these sucker plate headed
Speaker 2: remorras to continue with. And there's sometimes a little harder to.
Speaker 3: Figure out sort of gray area here.
Speaker 2: Yeah, sometimes, I mean again, this is often the case
Speaker 2: the deeper you look into any of these relationships. But basically,
Speaker 2: if you're not familiar with the remorra, ramorra's dorsal fin
Speaker 2: has evolved into an oval slatted sucker organ, so like
Speaker 2: by flexing the little slats on there, they can suction
Speaker 2: onto a surface such as the side of a whale
Speaker 2: or a shark or you know, a turtle or a
Speaker 2: ship or a human diver. I think it occurs occasionally.
Speaker 2: They're free swimming fish, but they like to hitch a ride,
Speaker 2: and there are many different species, and yeah, they attach
Speaker 2: to all sorts of organisms, including manta rays, and indeed
Speaker 2: they've been known to take up more or less permanent residents,
Speaker 2: sometimes inside a manta's mouth or hide in other body
Speaker 2: openings such as gills or the cloeca. They typically feed
Speaker 2: on the ectoparasites and loose skin flakes and other leavings
Speaker 2: of an organism. And yeah, it seems to be what's
Speaker 2: happening with manta rays. Not every variety of remora that
Speaker 2: latches onto a manta can keep up with it, can
Speaker 2: remain with the host, especially as it ventures into deeper waters.
Speaker 2: Some get displaced, And in general, it seems like the
Speaker 2: longer a manta hangs out in a shallow reef environment,
Speaker 2: the more it's liable to attract ramoras. So that's the
Speaker 2: case I've read with certainly the reef manta over the
Speaker 2: oceanic manta. And then it's also the case with mantas
Speaker 2: hanging out closer to shallow waters due to some particular
Speaker 2: state of their own life cycle. Now, the book that
Speaker 2: I keep referring to in these episodes Guide to the
Speaker 2: Manta and Devil Rays of the World by Stevens, Fernando Dando,
Speaker 2: and Discaria. In this they point out that scientists often
Speaker 2: cleanly label this relationship between the remoras and the manta
Speaker 2: rays as parasitic are arguing there's no real benefit for
Speaker 2: the mantis here. For instance, the gill activity going in
Speaker 2: and out of the gills can result in heavy scarring
Speaker 2: for example, essentially like mutilating the gills over time. Now,
Speaker 2: others argue, well, the remorras does seem to do some
Speaker 2: level of cleaning though they're eating up parasites, you know,
Speaker 2: dead skin flakes, and this, they would point they point out,
Speaker 2: would be helpful, especially to the oceanic manta, as it
Speaker 2: frequents cleaning stations far less as we'll be discussing. Cleaning
Speaker 2: stations tend to be you know, in reef environments, and
Speaker 2: if you're out there in the middle of it, there
Speaker 2: are fewer of these around. So perhaps the assistance in
Speaker 2: these cases would balance out the harm at least to
Speaker 2: some degree. Maybe it's not. I mean, I don't know
Speaker 2: how often you really see a fifty to fifty split
Speaker 2: with these relationships in nature, Like you know, there's there's
Speaker 2: gonna be you know, all the factors of evolution and
Speaker 2: behavior or in play here, and it's this is ever
Speaker 2: the question when we're pondering relationships like this.
Speaker 3: So for a very rough analogy, It's kind of like
Speaker 3: if you had a squirrel that lived on your body
Speaker 3: and it climbed all over you, eating the fleas that
Speaker 3: you also have eating the fleas and mosquitoes that swarm
Speaker 3: your skin. So that's good, you don't want the fleas
Speaker 3: and mosquitos. But also the squirrel's claws are like scratching
Speaker 3: you up, and it's probably causing problems while you're trying
Speaker 3: to move around. So you get a plus an a minus.
Speaker 2: Yeah, I mean it always reminds me of the Doctor
Speaker 2: Seuss book Thidwick the Big Hearted Moose. This is it's
Speaker 2: not a situation where Fidwick's dealing with parasites and creatures
Speaker 2: eating the parasites, but he's he has a big heart,
Speaker 2: and he keeps letting animals ride in his antlers until
Speaker 2: it gets out of hand.
Speaker 3: I feel like it's got to be one of the
Speaker 3: less big hearted Doctor Seuss books.
Speaker 2: Yeah, the message there is maybe a little less less rosy,
Speaker 2: but I don't know. I do come back to it
Speaker 2: and think about it from time to time. Though you
Speaker 2: know that in the Sleep book, I guess really really home.
Speaker 2: But at any rate, this is the case with large
Speaker 2: organisms like this, there's just much more space for ectoparasites
Speaker 2: to get everywhere, and parasites have their own parasites. Filter
Speaker 2: feeders also swim around with their mouths wide open while feeding.
Speaker 2: You know, they're bringing organisms into their mouth and that
Speaker 2: can bring in extra creatures as well, So you know,
Speaker 2: what is a manta to do. Breaching may help, as
Speaker 2: we discussed, as it may help with other marine organisms. Again,
Speaker 2: as we just mentioned, they can shake some of their
Speaker 2: hangers on via their deeper dives. But at the end
Speaker 2: of the day, they're going to need some help. They
Speaker 2: can't turn to each other. They don't really have much
Speaker 2: in the way of you know, limbs. They can't groom
Speaker 2: each other in the way that say primates do. So
Speaker 2: they're going to have to head to the cleaning stations.
Speaker 3: All right, So we're finally here. Tell me about the
Speaker 3: cleaning stations, all.
Speaker 2: Right now, I want to add a caveat I am
Speaker 2: very likely to accidentally call a cleaning station a feeding station.
Speaker 2: I've been doing this in casual conversation over and over
Speaker 2: again over the past several weeks, perhaps in part because
Speaker 2: for the fish working and some I'm shrimp working at
Speaker 2: these cleaning stations. It is a feeding station because that's
Speaker 2: what they're doing. They're feeding, that's what they're getting out
Speaker 2: of it. Ultimately, were talking about a cleaning symbiosis situation
Speaker 2: that benefits all of the organisms involved, and it's not
Speaker 2: unique to mantus. You'll find the scenario throughout the aquatic environment,
Speaker 2: both in fresh water and saltwater. Fish deal with their
Speaker 2: individual parasite loads in a variety of ways, but it's
Speaker 2: often useful to get some help. These relationships have developed
Speaker 2: over time in which fish will seek out areas populated
Speaker 2: by various other organisms that generally we're talking and certainly
Speaker 2: in marine environments about small reef fishes. Also sometimes some
Speaker 2: shrimp are involved in this, and there are various examples
Speaker 2: of this outside of the water as well. For instance,
Speaker 2: on land, examples such as the crocodile and the Egyptian
Speaker 2: plover or crocodile bird have been observed since ancient times.
Speaker 2: You can find like Herodotus writing.
Speaker 3: About this and still cute to see today.
Speaker 2: Yeah, this is the bird that goes inside the crocodile's mouth,
Speaker 2: holds the mouth open, goes in there and starts doing
Speaker 2: some dental cleanup. The Egyptian plover by the way, not
Speaker 2: to be confused with Egyptian lever. That's a that's a
Speaker 2: musical artist, a legendary musical artist that I've referenced on
Speaker 2: the show before. Look it up, kids. The oxpecker is
Speaker 2: a great example from the surface world as well, a
Speaker 2: bird that feeds exclusively on the bodies of large mammals,
Speaker 2: though this one is also much discussed in scientific circles
Speaker 2: because it's definitely a case where there are strong arguments
Speaker 2: to be made that the oxpecker might not ultimately help
Speaker 2: the organism that it's landing on all that much, and
Speaker 2: might be as much of a nuisance in and of
Speaker 2: itself in the ocean. To return to the waters, however,
Speaker 2: you see various fish take advantage of these services, including
Speaker 2: the parrotfish, which were previously discussed on the show. So
Speaker 2: you don't have to be a behemoth to benefit from
Speaker 2: a visit to the various organisms that want to eat
Speaker 2: your parasites, as well as perhaps some loose, dry skin
Speaker 2: or rancid flesh around your wounds. In fact, some cleaners
Speaker 2: are specialized wound cleaners. But naturally, when you're a large
Speaker 2: fish riddled with parasites, you know you can't scratch those
Speaker 2: itches again, so manta rays have to head to these stations,
Speaker 2: and it seems again, it seems to work for everyone.
Speaker 2: Small Fish and shrimp can't swim as far or do
Speaker 2: so safely in search of food, so they'll, you know,
Speaker 2: they set up at a cleaning station. Generally this is
Speaker 2: like a rocky outcropping the edge of a reef or
Speaker 2: you know, something like that, and here they can just
Speaker 2: hang out and their meals will be delivered to them
Speaker 2: because the customers will show up. They will go where
Speaker 2: the cleaner organisms.
Speaker 3: Are right, So by being easy to locate and offering
Speaker 3: a service, they can have this dependable influx of resources
Speaker 3: from abroad. It almost makes me think about like the
Speaker 3: economies of I don't know, freeway exits where there will
Speaker 3: be you know, gas stations and restaurants built up around
Speaker 3: a freeway exit, like you know the traffic's coming in.
Speaker 2: Yeah, yeah, exactly. I mean that you often see this
Speaker 2: compared to like a trip to the barber, the dentist,
Speaker 2: and so forth, all wrapped into one. Because yeah, they'll
Speaker 2: they'll get inside the mouth to clean out the teeth,
Speaker 2: they'll clean out gills, they'll eat away algae. Growths, dead
Speaker 2: and molting skin, bacterial fungal growths, you know, getting food
Speaker 2: particles out of the mouth. It's really quiet extensive. And
Speaker 2: then these are generally small organisms that are doing this,
Speaker 2: so they can target those tiny acto parasites and seek
Speaker 2: them out all over the host's body in every every
Speaker 2: crevice yum yum. And so the mantas actually the kind
Speaker 2: of queue up for this. If one of the bits
Speaker 2: of advice that the the the Snorkel guides had for
Speaker 2: us was was, you know, among all the reasons not
Speaker 2: to get too close is you also don't want to
Speaker 2: essentially enter the cleaning station, not because the fish are
Speaker 2: going to clean you, but because the mantas are going
Speaker 2: to be like, oh, it's occupied, I can't go in there,
Speaker 2: Like you're taking up room. It's like you've pulled into
Speaker 2: the car wash ahead of people who want their car cleaned.
Speaker 2: What would they do?
Speaker 3: Would they patiently wait their turn?
Speaker 2: Maybe? Or potentially clear? I mean also the humans being
Speaker 2: where they need to be. I think they're a number
Speaker 2: of reasons that they might sort of scare them off.
Speaker 2: You know, yeah, like you're too loud with your flippers,
Speaker 2: you're coming out of the water too much. I think
Speaker 2: in general they might just decide well, another time enough
Speaker 2: to bring it back to Fidwick, the big hearted moose.
Speaker 2: I you know, I don't think he ever considered visiting
Speaker 2: a wolf cleaning station or something for all of those
Speaker 2: various mammals and birds living on his antlers. Now. As
Speaker 2: discussed before, again, symbiosis is a spectrum and it can
Speaker 2: shift with either party reaping more of the benefits and
Speaker 2: in some cases perhaps taking a bit of advantage, at
Speaker 2: least from the human perspective. So some cleaner species do
Speaker 2: seem to agage engage. This is in general in occasional
Speaker 2: acts that feel more parasitic, like maybe they're you know,
Speaker 2: they're eating parasites, but maybe they're eating a little body
Speaker 2: mucus off of the surface of a fish or aquatic
Speaker 2: creature as well. You know, maybe they're grabbing a little
Speaker 2: flesh that's less on the rancid side, but you know,
Speaker 2: just because they can. So, you know, I guess to
Speaker 2: answerpomorphize the scenario, there are always going to be some
Speaker 2: bad actors, maybe some folks who take advantage of the
Speaker 2: trust in a given scenario. But I think still on
Speaker 2: the whole, even with the cases, cleaning stations seem to
Speaker 2: benefit everyone, even if sometimes there's a little advantage taken. Yeah.
Speaker 3: Well, and all kinds of organisms have symbiotic relationships that
Speaker 3: are sort of balanced on a knife's edge like this.
Speaker 3: I mean, I would say it's true of us with
Speaker 3: our own microbiota. You know, of course, human beings rely on,
Speaker 3: for example, our gut flora in order to do all
Speaker 3: kinds of things you know, to be healthy, to help
Speaker 3: with digestion. So we're definitely worse off without it. We
Speaker 3: need it, but at the same time, it can turn
Speaker 3: opportunistic and it can harm us if you know, there's
Speaker 3: something wrong with the immune system or other kinds of
Speaker 3: conditions come online.
Speaker 2: Now, there are some additional levers that the manta ray
Speaker 2: can pull and stevens that I'll get into this in
Speaker 2: the guide book. These are things that the manta will
Speaker 2: also do it feeding stations, which it makes sense. The
Speaker 2: manta knows that it is at a location where the
Speaker 2: local population is heavily invested in in the manta's parasites,
Speaker 2: its previous meals, and so forth. So first of all,
Speaker 2: they frequently defecate at these cleaning stations, makes sense, I mean,
Speaker 2: with all creatures, and stuff that's defecated is going to
Speaker 2: include things that are still of interest to various scavenging creatures.
Speaker 2: They will also cough or vomit, blasting particles like food
Speaker 2: particles out of their mouth, which cleaners are also going
Speaker 2: to be interested in. And Steven said all right that
Speaker 2: sometimes they blast out massive clumps of undigested zooplankton exoskeletons.
Speaker 2: I don't have a photograph to refer to, but I
Speaker 2: just have like a mental image of what this might
Speaker 2: look like. And then back to their defication. They'll also
Speaker 2: invert their intestines up to thirty centimeters or twelve inches
Speaker 2: out of their cloaca while they're doing it, just to
Speaker 2: better clean everything out that's feces, but also parasites, presumably
Speaker 2: indo and ectoparasites, And interestingly enough, their feces i've read
Speaker 2: is basical dark red due to all the plankton. So
Speaker 2: when they do this, if you're in the water with them,
Speaker 2: and you know, they don't care if you're in the
Speaker 2: water when they when they do this, they're gonna they're
Speaker 2: they're gonna let loose as needed. This process has often
Speaker 2: been misinterpreted by divers as like they don't know what
Speaker 2: they're looking at. It looks like it might be blood
Speaker 2: or something. Maybe they're injured, or in some cases they
Speaker 2: might think they're about to view a berth, which makes
Speaker 2: sense when you look at We talked about this video
Speaker 2: footage in the last episode from an aquarium in Okinawa, Japan,
Speaker 2: where we see one of the very few recordings of
Speaker 2: a manta giving birth, and it does like like this
Speaker 2: initial discharge of particles in the water. I can see
Speaker 2: where you might confuse the two acts.
Speaker 3: A burrito in the middle of a cloud, and then
Speaker 3: the burida unfolds.
Speaker 2: Yeah, so that might be a case where someone's like, oh,
Speaker 2: I think it's giving birth, but then you realize, oh,
Speaker 2: there's no baby. It's it's just a cloud of red
Speaker 2: manta fecal matter.
Speaker 3: They're just out part of their own intestines to get
Speaker 3: it all cleaned out.
Speaker 2: Yeah, that's right. Yeah, all right, Joe, I believe there's
Speaker 2: at least one more organ we want to talk about
Speaker 2: inside the manta's body, right, that's right.
Speaker 3: We wanted to come back to the subject of manta
Speaker 3: brains and intelligence, so we already talked in previous parts
Speaker 3: of this series about how when people have close encounters
Speaker 3: with manta rays they often report similar feelings. You'll read
Speaker 3: about this in people describing their dives with them. The
Speaker 3: manta is a fish, but it does not feel like
Speaker 3: a fish when you're in its presence. It has a
Speaker 3: kind of palpable intelligence and emotionality, a sense of curiosity
Speaker 3: that we generally only associate with social mammals and maybe
Speaker 3: sometimes with other strange intelligences like that of an octopus,
Speaker 3: but certainly not with fish. You'll read about this over
Speaker 3: and over with these manta experiences. Now, of course, that
Speaker 3: feeling of being in communion with a higher intelligence, it's
Speaker 3: just a subjective impression people have. Could be an illusion.
Speaker 3: Maybe it's based in some kind of esthetic charisma, something
Speaker 3: about the way the manta looks, or something about the
Speaker 3: way it moves. The question would be, is there any
Speaker 3: objective scientific reason for thinking there's actually something special about
Speaker 3: the intelligence of the genus mobula compared to other fish.
Speaker 3: I think the answer is pretty clearly yes.
Speaker 2: Yeah, that's my indication as well, because you know, to
Speaker 2: your point, people have this feeling about their dogs and
Speaker 2: cats all the time. Not to discount the intelligence of
Speaker 2: dogs and cats, which is with each of which are unique.
Speaker 2: But like we have this of course amazing human ability
Speaker 2: to anthropomorphize, to personify, and imbue just about anything with
Speaker 2: a remarkable level of intelligence and free will.
Speaker 3: Well, yes, that is certainly true. I mean I have
Speaker 3: the beholder quality to this whole thing. But I would
Speaker 3: also say that, even just somewhat objectively, I think dogs
Speaker 3: and cats, as somewhat social mammals do have a higher
Speaker 3: level of cognitive complexity than most fish. You could argue, yes, yeah,
Speaker 3: absolutely so, there are definitely I of the beholder elements.
Speaker 3: These are mammals that need to navigate a somewhat socially
Speaker 3: complex world. That they've got something going on up there.
Speaker 2: Well, let's dig into the old mantamelon what are they
Speaker 2: working with up there?
Speaker 3: Okay, First of all, I think we should address the
Speaker 3: question of raw hardware. What kind of neural equipment do
Speaker 3: manta rays and devil rays have to work with? And
Speaker 3: to get into this question, I wanted to look at
Speaker 3: a paper by a name you'll see popping up a
Speaker 3: whole lot in manterray research. This was by a researcher
Speaker 3: named scilla Ari that's spelled CSI L. L. A and
Speaker 3: then the last name is Ari If you want to
Speaker 3: look her up. Her research is all over the place.
Speaker 3: She studies manterray neurobiology and the paper is called in
Speaker 3: Cephalization and Brain organization of mobulid rays myleobataforms Elasmo Bronchi
Speaker 3: with ecological perspectives. This was published in the Open Anatomy
Speaker 3: Journal in twenty eleven. And so this paper set out
Speaker 3: to measure the brain size of three different species in
Speaker 3: the genus Mobula. It looked at Mobula japanica or the
Speaker 3: spinetiale devil ray also known as the Japanese devil ray,
Speaker 3: Mobula Thurstoni or the bent fin devil ray, and Mobula birostras,
Speaker 3: known at the time this paper was published as Manta birostras.
Speaker 3: Manta was once treated as a separate genus, but now
Speaker 3: the mantas are grouped with the rest of the Mobula genus.
Speaker 3: But anyway, this is the giant oceanic manta ray. This
Speaker 3: is the big one, the biggest of them all. So
Speaker 3: to run through a selection of some of the main findings.
Speaker 3: First of all, the giant oceanic mantray Biostras has the
Speaker 3: largest brain of any known fish species. It's just in
Speaker 3: absolute terms, biggest brain of all the fish. Also, mantas
Speaker 3: and devil rays not only have large brains in absolute terms,
Speaker 3: but they have very high brain to body mass ratios.
Speaker 3: This is known in anatomy as the encephalization quotion. So
Speaker 3: a larger brain is not always a sign of greater intelligence,
Speaker 3: at least when measured along the dimensions of intelligence that
Speaker 3: we find interesting. Often a large brain in an animal
Speaker 3: is necessary, especially when the animal is itself large, simply
Speaker 3: to control movement and nerve feedback for that massive body.
Speaker 3: So if you have a huge body, you need to
Speaker 3: control a lot of big muscles all over the place.
Speaker 3: You need to get sensory feedback from all over the body,
Speaker 3: so you need a big brain just to handle all that.
Speaker 3: It might not necessarily be for the kinds of things
Speaker 3: we think of when we say the word intelligence, things
Speaker 3: like problem solving, memory learning, social cognition, that sort of thing.
Speaker 3: What tends to correlate more often with those kinds of
Speaker 3: intelligence is having a bigger brain relative to the size
Speaker 3: of your body. And even then, the relationship between in civilization,
Speaker 3: quotient and observed intelligence is not completely linear, but it's
Speaker 3: a fairly strong relationship in terms of the structure of
Speaker 3: the brain and the characteristics of the brain tissue. These
Speaker 3: rays showed first of all, an enlarged telencephalon. The telencephalon
Speaker 3: is the four brain, the front part of the brain
Speaker 3: corresponding to the cerebrum in mammals, and also what the
Speaker 3: author calls a highly foliated cerebellum, and this means that
Speaker 3: the cerebellum has a more folded texture, which increases the
Speaker 3: surface area of the cerebellum and that in turn increases
Speaker 3: the number of neurons and the density of neurons on
Speaker 3: the cerebellum, allowing more connections and thus greater information processing power.
Speaker 3: And these anatomical features, the larger teleencephalon and the more
Speaker 3: highly foliated cerebellum are correlated with more complex behavior and
Speaker 3: cognition in other species. So just looking at their brains
Speaker 3: and brain tissue, it definitely does look like something special
Speaker 3: is going on with the mobula rays. Compared to other fish.
Speaker 3: You're seeing patterns that you see more with smarter animals
Speaker 3: across different types of lineages.
Speaker 2: There's a great illustration in the Manta and Devil Rays
Speaker 2: of the World book where they show on one hand,
Speaker 2: the brain of a spinetailed devil ray mobula mobular, and
Speaker 2: then they compare it to the brain of a similarly
Speaker 2: sized common skate. You know, so this is a not
Speaker 2: unrelated creature, similar size, and you can see like drastic
Speaker 2: difference between the two. The ray's brain just looks absolutely
Speaker 2: bloated and in gorge, you know, and then the skate's
Speaker 2: brain is streamlined and by comparison, so you know, even
Speaker 2: not knowing exactly what sorts of neural tissues you're looking at,
Speaker 2: you can see like, oh, this thing looks super charge.
Speaker 2: This one looks oversized compared to a similarly sized organism. Yeah.
Speaker 3: This paper also has some very juicy illustrations and some
Speaker 3: fiend without a face kind of stuff.
Speaker 2: Yeah, yeah, definitely.
Speaker 3: But anyway, so the question would be, what is all
Speaker 3: of this high powered neural equipment for. What would they
Speaker 3: need these powerful and highly foliated brains for. One possible
Speaker 3: explanation that Ari gets into in this paper is complex
Speaker 3: social behaviors. As we already discussed in the previous episodes,
Speaker 3: mobular rays show these interesting, complicated group behavior patterns. Examples
Speaker 3: of this would include forming schools that engage in coordinat
Speaker 3: and organized feeding behaviors. So remember that chain feeding where
Speaker 3: they'll go in a line feeding together, or cyclone feeding
Speaker 3: where they go in a circle. They organize into these
Speaker 3: patterns to take better advantage of food sources. Also, another
Speaker 3: example of group coordinated group behavior patterns are when they
Speaker 3: get into these large mate fitness competitions with potentially dozens
Speaker 3: of rays chasing around in these athletic courtship displays. Broadly,
Speaker 3: the management of complex social relationships and social behaviors is
Speaker 3: thought to be one of the key drivers of brain
Speaker 3: evolution in other species. So when you need to navigate
Speaker 3: a complex social landscape full of other members of your
Speaker 3: species and you need to maybe work together and manage
Speaker 3: relationships like recognizing specific individuals of your species and remembering
Speaker 3: interactions with them you've had in the past, that is
Speaker 3: often when evolution starts really putting pressure on you to
Speaker 3: wise up. That is thought to be a big driver
Speaker 3: of brain evolution in other lineages. We've already talked about
Speaker 3: evidence of mantas working together and engaging in these complex
Speaker 3: group behaviors, but is there any evidence that they do
Speaker 3: what I was just saying that they recognize and remember
Speaker 3: each other as individuals. In effect, do they have time
Speaker 3: stable social relationships. I went looking for an answer here
Speaker 3: and I found it seems to be yes, there is
Speaker 3: some evidence of that. So I came across a paper
Speaker 3: by Perryman at All published in the journal Behavioral Ecology
Speaker 3: and Sociobiology in the year twenty nineteen called Social Preferences
Speaker 3: and Network Structure and a Population of reef manta rays.
Speaker 3: Rob very interesting connection for you. In this paper to
Speaker 3: study the social networks of mobular rays, the authors here
Speaker 3: collected data on more than five hundred groups of reef
Speaker 3: manta rays this is the species Mobula alfredi over five
Speaker 3: years in raja Ampat in Indonesia. So this may have
Speaker 3: been in some of the same locations or around some
Speaker 3: of the same locations you visited.
Speaker 2: Yeah, I mean, I'm looking at the maps in the
Speaker 2: paper now and like, yep, yep, I was in that square.
Speaker 3: And so in observing the mantas in these locations, the
Speaker 3: authors did indeed observe what they call social preferences in
Speaker 3: mobular rays, especially between females. And social preferences here would
Speaker 3: mean that individual rays seem to show either an increased
Speaker 3: tendency to affiliate with or a desire to avoid specific
Speaker 3: other individual rays to anthropomorphize a bit, So this might
Speaker 3: kind of give the wrong idea, but roughly they had
Speaker 3: something analogous to friends and enemies.
Speaker 2: Room for frenemies in that equation or is that more
Speaker 2: of a human thing unclear.
Speaker 3: Yeah, we'll see what we think. So the authors found
Speaker 3: pretty strong evidence for female mantas having these relationships on
Speaker 3: both long and short time scales, so in the scale
Speaker 3: of weeks and months, they might have a consistent preference
Speaker 3: for or against certain other female individual rays. They also
Speaker 3: found pretty strong evidence for mixed sex social preferences kind
Speaker 3: of friendships or enemy ships between males and females. Between males,
Speaker 3: they only found kind of weak evidence for short term relationships,
Speaker 3: so perhaps males are less social with each other on average.
Speaker 3: The overall social networks were categorized as what they call
Speaker 3: a dynamic fission fusion society, with differentiated relationships linked to
Speaker 3: strong fidelity to cleaning station sites. So this idea of
Speaker 3: a fission fusion society is one whether it's not like
Speaker 3: a fixed group that stays together for you know, the
Speaker 3: duration of these animals lives. They're kind of like these
Speaker 3: groups that come together for some period of time and
Speaker 3: then split apart and then can dissolve, and then different
Speaker 3: groups can kind of reform. It's a more more freeform
Speaker 3: kind of social network formation and division. And then in
Speaker 3: their discussion section, the authors say, quote, our results show
Speaker 3: that stable, differentiated social relationships lasting over several weeks or
Speaker 3: months are an important driver of group structures in reef
Speaker 3: manta rays, which suggests that both familiarity and long term
Speaker 3: social relationships are important in structuring their societies. In complex
Speaker 3: social systems, such capabilities can be essential too, identify partners
Speaker 3: in reciprocal altruism, to maintain social hierarchies, and to avoid inbreeding.
Speaker 3: So those three things are strong biological reasons why it
Speaker 3: might be useful to remember who another individual of your
Speaker 3: species is and remember past interactions with them, be able
Speaker 3: to repay favors back and forth, you know, reciprocal altruism,
Speaker 3: or remember if they did something mean to you in
Speaker 3: the past. To avoid inbreeding, of course, and to maintain
Speaker 3: kind of dominance relationships. So anyway, it seems yes, the
Speaker 3: answer is modular rays do seem to be especially social
Speaker 3: relative to most fish, and social cognition pressures are thought
Speaker 3: to be a big driver of brain evolution in other
Speaker 3: vertebrate lineages, so that could be a big factor at
Speaker 3: play here. We don't know for sure, but that seems
Speaker 3: like a very plausible explanation for why these animals would
Speaker 3: need to have more powerful brains. Any other reasons they
Speaker 3: might need to have extra brain power, yes, or He
Speaker 3: gets into some other ideas as well. One is the
Speaker 3: need to understand their spatial firement. So mobulids are pelagic fish,
Speaker 3: and they often inhabit coastal waters, including places like reefs
Speaker 3: and seamounts and so forth, and Ari says that there
Speaker 3: may be an evolutionary pressure for them to learn the
Speaker 3: quote complex spatial organization of these habitats, which I think
Speaker 3: that would include like creating mental maps of not only
Speaker 3: the underwater topography of like a reef or a seamount,
Speaker 3: but I think it would also include dynamic elements across
Speaker 3: these maps, like water currents and the presence of other
Speaker 3: organisms such as prey or predators or especially cleaning mutualists.
Speaker 3: Another possible explanation for their neurobiology is what Ari calls
Speaker 3: their active and maneuverable lifestyles. She points out that in
Speaker 3: other species, high cerebellar foliation, which remember that's the folding
Speaker 3: of the cerebellum that allows more neuron density there. That
Speaker 3: is associated with, among other things, maneuverability and strong locomotor abilities,
Speaker 3: which Mobula rays absolutely do possess. You know, they're very acrobatic.
Speaker 3: They can move around a lot, and so their brain
Speaker 3: structures here could have something to do with their tendency
Speaker 3: toward acrobatics. Another thing, she points out, I thought this
Speaker 3: was kind of interesting. It could have something to do
Speaker 3: with their wide heads. Some aspects of the large brain
Speaker 3: and the powerful telencephalon of the manta ray could be
Speaker 3: related to the fact that they have a broad head
Speaker 3: similar to the hammerhead shark, which our rites could help
Speaker 3: with organizing and integrating different kinds of sensory feedback. Now
Speaker 3: I was confused about that at first. I was like,
Speaker 3: that doesn't come together for me, Like what's the deal.
Speaker 3: So I had to look this up to understand it better.
Speaker 3: But the idea is like in hammerhead sharks, the wide
Speaker 3: head and the hammerhead sharks also have an enlarged telencephalon
Speaker 3: the wide head and the enlarged telencephalon in the brain
Speaker 3: seem to help give the shark enhanced sensory abilities like
Speaker 3: electrosensory abilities, vision, and even maybe a more stereoscopic sense
Speaker 3: of smell, so they can determine the direction that smells
Speaker 3: are coming from more easily. So like by spacing out
Speaker 3: the sensory organs across a wider head, you can sort
Speaker 3: of increase the resolution you get across multiple different sensory modalities.
Speaker 3: It's again this is a loose analogy, but it's like,
Speaker 3: you know, having a bigger camera lens kind of like
Speaker 3: you're increasing the resolution you can get on things. And
Speaker 3: so the wide spacing there for chemical sensing or electrosensing
Speaker 3: and the hammer heads especially or vision and all that
Speaker 3: it can help you in a way. And then the
Speaker 3: strong tellencephalon the big four brain can help you gather
Speaker 3: and make sense of all that information. That does seem
Speaker 3: to be the case in hammerhead sharks, and Broadly already
Speaker 3: says it's possible that similar sensory management could be at
Speaker 3: play within mobula heads and brains. They also have these big,
Speaker 3: wide heads that are put the different sensors far apart.
Speaker 2: That's interesting. That makes me think about some of the
Speaker 2: hypotheses concerning breaching in mantas that like the slap of
Speaker 2: their bodies hitting the water again, could be a signal
Speaker 2: in some cases to other rays to come and start
Speaker 2: engaging in these social feeding configurations with them.
Speaker 3: Mmm. Yeah, okay, so you got.
Speaker 2: To receive that signal and then know what to do
Speaker 2: with it.
Speaker 3: And then finally there was an issue brought up in
Speaker 3: this paper that was a lot more interesting than I
Speaker 3: first realized once I started looking into it, and that
Speaker 3: was a little bit less directly related to intelligence, but
Speaker 3: very worth mentioning. And that's the idea of thermal issues.
Speaker 3: So I'm going to start with a quote from the
Speaker 3: paper here, Ari Write's quote endothermy as. The elevation of
Speaker 3: body temperature by metabolic heat production represents one of the
Speaker 3: most significant developments during vertebrate evolution that might be connected
Speaker 3: to enlarged brain size. Sharks in general are poikilothermic, meaning
Speaker 3: cold blooded. Their body temperature varies with the environment, but
Speaker 3: some shark species like Eshuris and Lamna, are homeothermic, and
Speaker 3: that in this case it means regionally warm blooded. They
Speaker 3: can keep blood in certain parts of their body elevated
Speaker 3: warm as they are able to maintain body temperatures well
Speaker 3: above ambient temperature of the environment by countercurrent flow of
Speaker 3: blood at certain places of their body. So countercurrent blood
Speaker 3: flow is another interesting phenomenon. It works essentially by positioning
Speaker 3: the hot pipes right next to the cold pipes. So generally,
Speaker 3: the blood that is returning to an animal's heart from
Speaker 3: its extremities through the veins is going to be cold.
Speaker 3: It goes out there to the edges of the body,
Speaker 3: it loses heat, and then it has to come back
Speaker 3: to the heart, so it gets cold and it's coming
Speaker 3: back cold. Meanwhile, arterial blood leaving the heart and headed
Speaker 3: for the extremities is comparatively warm. It just came from
Speaker 3: the warmest part of the body right there in the core.
Speaker 3: Countercurrent blood flow places long stretches of arteries right next
Speaker 3: to long stretches of veins, so that the warm blood
Speaker 3: coming from the core can warm up the cold blood
Speaker 3: in the veins before it gets back to the core.
Speaker 3: And even human bodies actually take advantage of this. In
Speaker 3: our arms and legs, the veins and arteries tend to
Speaker 3: be close to each other, sort of next to each
Speaker 3: other to help warm the cold blood returning from the
Speaker 3: fingers and toes, and this adaptation helps animals maintain higher
Speaker 3: body temperatures in cold environments. But sometimes it's not just
Speaker 3: positioning major vein and artery pathways next to each other.
Speaker 3: Sometimes there are dedicated structures in an animal's body that
Speaker 3: really maximize this artery to vein heat exchange. And one
Speaker 3: example of a structure like this would be what's called
Speaker 3: a red mirabulae chronica, which comes from the reading mirabilae
Speaker 3: comes from the Latin for wonderful net, and then the
Speaker 3: cranica would be of the skull, the wonderful net of
Speaker 3: the skull. This is a sort of dense web of
Speaker 3: veins and arteries inside the cranial cavity around the brain,
Speaker 3: which helps regulate the temperature of blood flow around the brain.
Speaker 3: Ari writes quote among mobulid rays in Mobula terrapacina and
Speaker 3: Manta birostras. Again, that's now Mobula birostras, a ret mirabulae
Speaker 3: cranica as a countercurrent heat exchanger has been described around
Speaker 3: their brain. Interestingly, the same families are also characterized as
Speaker 3: large brained elasmo bronchs, in which these unique adaptations might
Speaker 3: serve to enhance their ability to exploit cooler environments, either
Speaker 3: deeper water or at higher latitudes, with greater efficiency by
Speaker 3: slowing the rate of metabolic heat loss to the environment
Speaker 3: or allowing them a higher activity level. And I thought
Speaker 3: this was interesting. So I was reading a little bit
Speaker 3: more about this in a paper called Cranial endothermy in
Speaker 3: Mobulid rays Evolutionary and ecological Implications of a thermogenic brain
Speaker 3: by mc Arostigui in the Journal of Animal Ecology, twenty
Speaker 3: twenty four. And here the author makes a very interesting
Speaker 3: kind of comparison. So Arostigwi writes, quote, whereas early hominids
Speaker 3: in hot terrestrial environments may have experienced a thermal constraint
Speaker 3: to evolving larger brain size, cetaceans and mobulids, so like
Speaker 3: whales and rays here in cold marine waters may have
Speaker 3: experienced a thermal driver for enlargement of a thermogenic brain.
Speaker 3: So does that converse relationship make sense to like for
Speaker 3: human evolution, we want to have a bigger brain, right,
Speaker 3: bigger brain's great, you can get real smart. But heat
Speaker 3: concerns place among other things. Of course, you know, heat
Speaker 3: concerns place upper limits on our ability to grow bigger brains.
Speaker 3: Those brains can easily get too hot, which is dangerous
Speaker 3: to us. For mantas and devil rays, there could be
Speaker 3: an opposite direction thermal influence on brain evolution. The cold
Speaker 3: waters that you want to live in and dive down
Speaker 3: to make it pay thermally to have a bigger brain
Speaker 3: with this big mesh of blood vessels and so erostig
Speaker 3: Wei writes in the abstract quote the potential for brain
Speaker 3: enlargement to yield the dual outcomes of cranial endothermy and
Speaker 3: enhanced cognition in mobulids suggests one may be an evolutionary
Speaker 3: byproduct of selection for the mechanisms underlying the other, and
Speaker 3: highlights the need to account for non cognitive functions when
Speaker 3: translating brain size into cognitive capacity. So I thought that
Speaker 3: was a fascinating and this is not proven, but it's
Speaker 3: raising the possibility. What if mantas evolved greater intelligence as
Speaker 3: an accidental byproduct of growing bigger brains, which and the
Speaker 3: growing of the bigger brains was mainly driven in the
Speaker 3: first place by thermal pressure. You want to keep the
Speaker 3: brain warm when you're going into these cold waters.
Speaker 2: That's fascinating. So yeah, it would be the environmental reasons
Speaker 2: to have a big brain are like the main driving
Speaker 2: force here. But then the idea is that if this
Speaker 2: were true, they would also then of course use those
Speaker 2: cognitive powers to sort of flesh out their behavior as
Speaker 2: well well.
Speaker 3: Right, so, yeah, if you accidentally evolve a more powerful
Speaker 3: brain just because you're trying to keep a warmer brain
Speaker 3: in cold waters, that brings new capacities online which could
Speaker 3: further just arise as a contingency, but then could further
Speaker 3: shape your revolution if you lean into them.
Speaker 2: Ah. So it's like think of the There's a Marvel
Speaker 2: super villain called the Leader, and he has enlarged brain
Speaker 2: and he uses that brain power you know, you know
Speaker 2: for supervillain things to try and take over the world.
Speaker 2: But you could make an argument though the Leader didn't
Speaker 2: evolve or developed this massive brain to take over the world.
Speaker 2: He did it for thermal reasons. But then of course
Speaker 2: he's going to try and take over the world with
Speaker 2: it because he's got a big brain. As a result
Speaker 2: of these these thermal conditions.
Speaker 3: World domination plots an unfortunate side effect of keeping a
Speaker 3: nice and toasty up there. So that's an interesting possibility
Speaker 3: fascinating question. I'd never considered anything like that. So that's
Speaker 3: all I've got from that original paper by sila Ari
Speaker 3: on the neurobiology of the mantas and the devil rays here.
Speaker 3: But there was one more thing I wanted to mention
Speaker 3: about mobular ray brains and intelligence, and that is there
Speaker 3: is there's one famous experiment which showed that manta rays may,
Speaker 3: depending on your interpretation, pass a well known animal cognition
Speaker 3: milestone known as the mirror self recognition test. So we've
Speaker 3: talked about this test on the show before, but if
Speaker 3: you never heard of it, the most common version goes
Speaker 3: like this. You place a mark somewhere on an animal's body,
Speaker 3: somewhere that they wouldn't be able to see it just
Speaker 3: by looking directly at themselves, but somewhere they could see
Speaker 3: with the aid of a mirror. So for a human example,
Speaker 3: you could imagine putting a spot of dye on the skin,
Speaker 3: maybe on the front of your throat. So you look
Speaker 3: in a mirror, you'll see it, but you can't see
Speaker 3: it by looking down. Yeah, then you give that animal
Speaker 3: a mirror and you watch what they do. Most animals
Speaker 3: do not seem to recognize their reflections as themselves. A
Speaker 3: lot of animals will just kind of ignore a mirror.
Speaker 3: Sometimes they react as if it were another an in
Speaker 3: their space, So they react, you know, maybe they puff
Speaker 3: up and get aggressive, or they try to interact with
Speaker 3: it somehow, or they just act confused. A small number
Speaker 3: of animals, including some of the great apes, some marine
Speaker 3: mammals like bottlenosed dolphins, I think, maybe orcas, some corvids,
Speaker 3: and know the magpie. I believe elephants may have passed
Speaker 3: the mirror test. They do something different. They will touch
Speaker 3: their own bodies on the spot with the mark and
Speaker 3: try to rub it off if they can. Sometimes, because
Speaker 3: of different animal body plans, you have to organize different
Speaker 3: sort of equivalents here. But they will see the mark
Speaker 3: and they will try to mess with it, indicating that
Speaker 3: they understand the animal they're looking at in the mirror
Speaker 3: is the self and not another. That's my own body,
Speaker 3: and I react by touching the part of my body
Speaker 3: that I see as modified in the mirror.
Speaker 2: Yeah, it's something we take for granted because we do
Speaker 2: it every day, but if calibrated just right, it can
Speaker 2: arguably give us some insight into what might be happening.
Speaker 2: Inside the brain the mind of a non human.
Speaker 3: Animal, right, and so this is taken as evidence of
Speaker 3: rare self awareness, though we should strongly caveat this because
Speaker 3: that phrase can bring a lot of associations or baggage
Speaker 3: that are not necessarily proven by these experiments. There is
Speaker 3: debate over exactly what the mirror test shows, but even
Speaker 3: with that big asterisk there, I do think the results
Speaker 3: of these experiments are fascinating. Like most animals don't recognize
Speaker 3: that the mirror reflection is their own body, a few
Speaker 3: animals do appear to recognize that. What about mopular rays, well,
Speaker 3: there was a paper published in the Journal of Ethology
Speaker 3: in the year twenty sixteen by same author as before
Speaker 3: sila Ari but also Dominic P. Dagostino, called contingency checking
Speaker 3: and self directed behaviors in giant manta rays do elasmo
Speaker 3: broncs have self awareness, and so the authors set this
Speaker 3: up in their abstract by saying, quote, manta rays have
Speaker 3: a high encevilization quotion. As we already talked about it,
Speaker 3: Remember large brains compared to their body size, similar to
Speaker 3: those species that have passed the mirror self recognition test
Speaker 3: and possessed the largest brain of all fish species. Again,
Speaker 3: that would be in the mobula of Birostris, the giant
Speaker 3: oceanic mantray, biggest fish brain. They write quote in this study,
Speaker 3: mirror exposure experiments were conducted on two captive giant manta
Speaker 3: rays to document their response to their mirror image. So
Speaker 3: this test was different from the standard format than that
Speaker 3: I just described a minute ago because the authors were
Speaker 3: not able to do the body mark component of the test,
Speaker 3: And there are some good reasons for thinking about that.
Speaker 3: For one, thing like mantas don't have hands, so they
Speaker 3: can't reach out and tut. There's nothing they have that's
Speaker 3: prehensile they can use to reach out and touch a
Speaker 3: part of their body to mess with it. So it
Speaker 3: didn't have that important body mark component of the test.
Speaker 3: That places some major limits on how to interpret these
Speaker 3: results when compared to the results of many other mirror
Speaker 3: test experiments. But the authors did document the manta's behavior
Speaker 3: in response to the presence of a mirror, and then
Speaker 3: they controlled for that by just putting in a non
Speaker 3: reflective white board of the same size in their tank,
Speaker 3: and the results were really interesting. The mantas showed a
Speaker 3: lot of interest in the mirror like a lot of interest.
Speaker 3: They really were attracted to the mirror and they wanted
Speaker 3: to hang out around it. They spent a lot of
Speaker 3: time moving around in front of it and messing with it.
Speaker 3: They did not, on the other hand, attempt to interact
Speaker 3: socially with the mirror image. And the authors could measure
Speaker 3: this because there are certain kinds of physiological responses that
Speaker 3: mantas tend to show when in the presence of another
Speaker 3: another manta, like they might show like a kind of
Speaker 3: widening of spots, or like something kind of like changes
Speaker 3: on their coloration patterns, and they didn't observe anything like that.
Speaker 3: They did not see the behaviors you would normally see
Speaker 3: when a manta sees another of its species, so there
Speaker 3: were no signs that they thought of this as another animal.
Speaker 3: The author is right quote frequent, unusual and repetitive movements
Speaker 3: in front of the mirror suggested contingency checking. In addition,
Speaker 3: unusual self directed behaviors could be identified when the manta
Speaker 3: rays were exposed to the mirror. So what exactly do
Speaker 3: they mean by contingency checking. This seems to mean testing
Speaker 3: to see if the mirror image does the same things
Speaker 3: you do so you know, you might think of making
Speaker 3: faces in a mirror or like wiggling repetitively in front
Speaker 3: of a mirror, and they the arch yes, yeah, exactly, yeah,
Speaker 3: they were doing that. So exam they observed were things
Speaker 3: like positioning the body to stare into the mirror and
Speaker 3: then repeatedly wiggling the cephalic fins, like opening and closing
Speaker 3: the cephalic fins over and over, blowing bubbles into the mirror.
Speaker 3: And then also what about these unusual quote self directed behaviors.
Speaker 3: This is what look to the researchers like the manta
Speaker 3: trying to investigate parts of its own body that it
Speaker 3: can't normally see, like orienting so that it could look
Speaker 3: at the reflection of its ventral surface of its belly
Speaker 3: or part of its back for example. They note that
Speaker 3: quote body turns into a vertical direction, exposing the ventral
Speaker 3: side of the body to the mirror while visually oriented
Speaker 3: to it was something that they only ever saw the
Speaker 3: mantas do when the mirror was in the tank. So
Speaker 3: they take the mirror out. They don't see the mantas
Speaker 3: doing like orienting vertically like this and look, so it's
Speaker 3: like it looked to them like they were trying to
Speaker 3: see parts of their body that were not ever visible
Speaker 3: to them otherwise. So at the end of their abstract,
Speaker 3: they say, quote, the present study shows evidence for behavioral
Speaker 3: responses to a mirror that are prerequisite for a prerequisite
Speaker 3: of self awareness, and which has been used to confirm
Speaker 3: self recognition in apes. But again the authors do acknowledge
Speaker 3: the limitations. You know, this doesn't necessarily prove self awareness
Speaker 3: this version of the test. Of course, it did not
Speaker 3: include the mark checking component, and there are multiple ways
Speaker 3: you could interpret their behavior in front of the mirror.
Speaker 3: It's possible they didn't recognize it as themselves and we're
Speaker 3: just reacting with curiosity to something visually unusual. Though, the
Speaker 3: behaviors that look like, you know, checking out your belly
Speaker 3: flesh only when the mirror is around, that does sound
Speaker 3: pretty interesting to me.
Speaker 2: Yeah. Absolutely, Oh man, Yeah, I have a couple of
Speaker 2: thoughts on all of this. Like, on one level, I
Speaker 2: have to say that, you know, so like the hard
Speaker 2: science side, I do like the idea of leaning into
Speaker 2: interpretations of animals as being more conscious and having you know,
Speaker 2: if there's a case to be made, I'm like, let's
Speaker 2: go ahead and consider it, because if it helps protect
Speaker 2: a species like this, then all the better. On the
Speaker 2: other hand, like just the idea of let's go ahead
Speaker 2: and assume for the sake of argument that the manta
Speaker 2: does recognize the reflection as itself. What is that like
Speaker 2: for a cret Now granted, this is an aquarium scenario,
Speaker 2: so with the glass involved, there may be some other scenarios.
Speaker 2: But imagine a purely wild manta that has, as far
Speaker 2: as I'm imagining, it never encountered a reflection of itself,
Speaker 2: and then it is presented with one. What would that
Speaker 2: be like? What would that be like for a human being?
Speaker 2: If we managed to make it to adulthood without ever
Speaker 2: encountering an unnatural mirror, reflection or something like it, say,
Speaker 2: on the surface of water. I mean, I have no
Speaker 2: doubt that we'd be able to pass it. I mean,
Speaker 2: that's certainly part of the human mental capabilities. But but man,
Speaker 2: what would that what would that encounter be like?
Speaker 3: But the human I think, you know, you can see
Speaker 3: a lot of your own body, not the whole thing.
Speaker 3: You know, you got a lot of back, and you
Speaker 3: got a face and head and I guess all that.
Speaker 3: But you can see at least like the front of
Speaker 3: your body. Yeah, the mantas, I don't know, can they
Speaker 3: even see that? Again, it seems like they were very
Speaker 3: interested in checking out their their ventral side here, so
Speaker 3: they may have very very little visual awareness of themselves
Speaker 3: within their space ever, maybe all kind of like only
Speaker 3: proprioceptive awareness of their own body. Again, I'm not sure
Speaker 3: of that, but that's it seems plausible.
Speaker 2: Yeah, yeah, I think it's fascinating. Now were we kept
Speaker 2: talking about their their bellies, their ventral side, So I
Speaker 2: want to come back to this as we're we're closing
Speaker 2: out here. As we've mentioned, some mantas have distinct appearances
Speaker 2: because of significant scarring, you know, scarring from mating, scarring
Speaker 2: from predators interactions. And then you have mantas such as
Speaker 2: the celebrity manta Baba Ganoosh of the Maldives that apparently
Speaker 2: survived a rather horrific boat strike. You can look up
Speaker 2: images of this one. So these individuals you tend to
Speaker 2: stand out. But as we've discussed, their wounds tend to
Speaker 2: heal rapidly, you know, maybe not completely, and certainly in
Speaker 2: the case of severe injuries, not completely, but on the whole,
Speaker 2: these are changing markers. What doesn't change, however, are the
Speaker 2: dark spots on their bellies, on their ventral side. You
Speaker 2: can look up, you know, images of this, and if
Speaker 2: you've been in the water you might get to observe
Speaker 2: this as well. But yeah, you look at the ventral
Speaker 2: side of a manta and it is a unique fingerprint,
Speaker 2: the array of spots and blotches on their generally white bellies.
Speaker 2: It is, It is a fingerprint. It can be used
Speaker 2: to i D a particular manta, and scientists are able
Speaker 2: to put these into a database and track individuals without
Speaker 2: the aid of actual physical tracks or tax And it
Speaker 2: gets even cooler because you get into like a citizen
Speaker 2: scientist scenario here because you have the global ID the
Speaker 2: Manta Photo database, which via this database, anyone who swims
Speaker 2: in proximity to mantas. Again, I'm assuming by following all
Speaker 2: the rules, but if you manage to get a photos,
Speaker 2: particularly of their spots, they can I think other parts
Speaker 2: of the manta can also prove useful, but especially their spots.
Speaker 2: They can be uploaded into the database and this can
Speaker 2: be used to help study their movements and their behavior.
Speaker 2: And yeah, you can learn more about this at Manta
Speaker 2: Trust dot org. I believe we've referred to the Manta
Speaker 2: Trust already, and I'd say, in general, if you've been
Speaker 2: moved at all by anything we've discussed in these episodes
Speaker 2: about the manta, the plight of the manta, or the
Speaker 2: majesty of these creatures, visit Manta Trust dot org. You
Speaker 2: can learn more about them, you can sign up for
Speaker 2: their newsletter. You can support their work via donations and purchases.
Speaker 2: In fact, that book that I've been referring to, Guide
Speaker 2: to the Manta and Devil Rays of the World, is
Speaker 2: available to purchase there, and even if you don't purchase
Speaker 2: it directly from them, royalties from that book go to
Speaker 2: the Manta Trust. You can even this is this is
Speaker 2: super cool. You can of course adopt a manta. This
Speaker 2: is not uncommon. You can, you know, and but you
Speaker 2: can also pay to name a specific Maldives manta in
Speaker 2: their database. I was looking at this on their website.
Speaker 2: I think they had like four up for grabs. So
Speaker 2: these are mantas that have you know, like a technical tag,
Speaker 2: like you know, string of numbers and letters, but they
Speaker 2: don't have a fun name yet. And for a very
Speaker 2: reasonable donation, you can provide a name for such a
Speaker 2: Manta Ray.
Speaker 3: Do they place any limits on how stupid the name
Speaker 3: can be?
Speaker 2: I don't know. I mean, I mean there may be
Speaker 2: some reasonable limits there. I mean I would place reasonable
Speaker 2: limits if I were running this. But but yeah, I
Speaker 2: mean it makes me I kind of want to adopt
Speaker 2: a Manta Ray for the show. Could call it, I
Speaker 2: don't know, Blowfield, Stuffington or something. I wouldn't want it
Speaker 2: to be a complete.
Speaker 3: Advertiser Delia the self Aware.
Speaker 2: There you go at any rate check it out listeners.
Speaker 2: If you happen to adopt a Manta Ray or or
Speaker 2: name a Manta Ray via this website, let us know
Speaker 2: and we will. We will spread the will, spread the word,
Speaker 2: and we'll also look this Manta Ray up and see
Speaker 2: what they look like.
Speaker 3: Yeah, contact at stuff to Blow your Mind dot com.
Speaker 2: Let us know. All right, we're gonna go ahead and
Speaker 2: close these episodes out. I hope you've enjoyed them. Again,
Speaker 2: we'd love to hear from everyone out there. You have
Speaker 2: any experiences with Manta's, other rays, thoughts and anything that's
Speaker 2: discussed here right in. Yeah, send your photos. We'd love
Speaker 2: to see photos. We heard from some snorklers already, but
Speaker 2: not the sort of snorkelers. I was imagining. We'll get
Speaker 2: to that in a future listener mail episode, but we
Speaker 2: heard from some bog snortlers. Is that a joke?
Speaker 3: I couldn't tell.
Speaker 2: I could not tell. I haven't had a chance to
Speaker 2: research it yet, but I flagged that one to come
Speaker 2: back to. If it was a joke, it was elaborate.
Speaker 2: Those were I think real photos.
Speaker 3: We'll learn more and report.
Speaker 2: Just a reminder to everyone that's Stuff to Blow Your
Speaker 2: Mind is primarily a science and culture podcast, with core
Speaker 2: episodes on Tuesdays and Thursdays, short form episodes on Wednesdays
Speaker 2: and on Fridays. We set aside most serious concerns to
Speaker 2: just talk about a weird film on Weird House Cinema.
Speaker 3: Huge thanks as always to our excellent audio producer JJ Posway.
Speaker 3: If you would like to get in touch with us
Speaker 3: with feedback on this episode or any other, to suggest
Speaker 3: a topic for the future, or just to say hello,
Speaker 3: you can email us at contact stuff to Blow your
Speaker 3: Mind dot com.
Speaker 1: Stuff to Blow Your Mind is production of iHeartRadio. For
Speaker 1: more podcasts from my Heart Radio, visit the iHeartRadio app,
Speaker 1: Apple Podcasts, or wherever you're listening to your favorite shows
Speaker 2: With red Ratt