Speaker 1: Hey you welcome to Stuff to Blow your Mind. My
Speaker 1: name is Robert.
Speaker 2: Lamb and I'm Joe McCormick, and it's Saturday. We are
Speaker 2: bringing you an episode from the vault. This one originally
Speaker 2: published on June thirtieth, twenty twenty two, and it's part
Speaker 2: two of our series The Lesser of Two Crab Claws,
Speaker 2: about asymmetry in the natural world.
Speaker 3: Enjoy Welcome to Stuff to Blow Your Mind, a production
Speaker 3: of iHeartRadio.
Speaker 1: Hey, welcome to Stuff to Blow your Mind. My name
Speaker 1: is Robert Lamb.
Speaker 2: And I'm Joe McCormick, and we're back with part two
Speaker 2: of our series on asymmetry in life. Now. In the
Speaker 2: last episode, we talked about the concept of bilateral symmetry,
Speaker 2: where basically all of the higher animals have body plans
Speaker 2: where the left and the right sides are more or
Speaker 2: less a copy of one another. In other words, along
Speaker 2: one of the three dimensions of space, our bodies are
Speaker 2: approximately mirrored, at least on the outside. Now, in most organisms,
Speaker 2: there are minor variations on this type of symmetry, but
Speaker 2: occasionally there are species with isolated but radical deviations, where
Speaker 2: like one feature on the outside of an otherwise mirror
Speaker 2: flipped half of the body is drastically different from what
Speaker 2: you find on the other side. Examples that came up
Speaker 2: last time were the tusk of the nar wall, where
Speaker 2: in most cases it's actually the left maxillary canine tooth
Speaker 2: so weird it's the left fang basically of this whale
Speaker 2: stabbing through the upper lip and it becomes a single tusk.
Speaker 2: We also talked about the blowholes and skulls of toothed whales,
Speaker 2: such as the sperm whale, where in many cases these
Speaker 2: have developed left right mismatches that seem to have evolved
Speaker 2: to support the capacity for echolocation. We also talked about
Speaker 2: the cock eyed squid, which has two extremely different eyes
Speaker 2: for looking into extremely different worlds, one for the water above,
Speaker 2: which is filtering sunlight, and one for the water below,
Speaker 2: which may contain flashes of bioluminescence. And so today we
Speaker 2: wanted to pick up the series by talking about some
Speaker 2: more fascinating examples of lopsided animal evolution. Animals with halves
Speaker 2: that mostly match but in one capacity or another do not,
Speaker 2: and why that would be. Now, there are many great
Speaker 2: examples of asymmetrical evolution incrustations, and we may actually save
Speaker 2: some of these for the next part in the series.
Speaker 2: I know we're going to go to at least three
Speaker 2: parts here, but for today's episode, I wanted to start
Speaker 2: by getting out the lemon and the drawn butter, because
Speaker 2: this is an asymmetry that you don't have to be
Speaker 2: a specialist a marine biologist to notice for yourself. If
Speaker 2: you've ever eaten, or even just seen a cooked lobster,
Speaker 2: you probably have noticed a weird mismatch between the lobster's
Speaker 2: two claws. Rob, I assume you've you've seen this for yourself.
Speaker 1: Yes, yes, they're not not as recently as you have.
Speaker 1: Because I believe this this was the inspiration for this episode. Right,
Speaker 1: you recently ate a lobster?
Speaker 2: Oh, I don't. I don't think I even told you that,
Speaker 2: But yeah, this probably had something to do with it.
Speaker 2: I can't confirm the inner workings of my subconscious mind.
Speaker 2: But not too long ago, I was in the I
Speaker 2: was in New England where where lobster is king. I'm
Speaker 2: not gonna do the accent, but lobster is king. And
Speaker 2: I did. I did, in fact eat a lobster, and yeah,
Speaker 2: and I noticed stark differences between the claws, even not
Speaker 2: just looking at them, but in my fingers, you know,
Speaker 2: one claw was sort of a pleasure to crack open
Speaker 2: and get the meat out of, and the other one.
Speaker 2: When I handled the inside of the pincers, they were
Speaker 2: much sharper, and the spines within them were much smaller
Speaker 2: and kind of were irritating and unpleasant to the fingers.
Speaker 1: Fascinating.
Speaker 2: So what's going on with this claw mismatch? Oh and
Speaker 2: by the way, we should be clear that we're talking
Speaker 2: specifically about the American lobster or Homarus americanas this is
Speaker 2: the lobster you find along the northern edge of the
Speaker 2: eastern coast of North America, so all up through like
Speaker 2: the north half of the eastern United States and up
Speaker 2: into Canada.
Speaker 1: This is like the red lobster lobster, the lobster from
Speaker 1: your grocery store that has rubber bands on its claws,
Speaker 1: not like the Caribbean lobster.
Speaker 2: Yeah, not the rock lobster, though I hear those can
Speaker 2: be good eating too. I've never had man. But anyway,
Speaker 2: so the American lobster. So you look at these two claws,
Speaker 2: and what you'll notice is that usually one claw is
Speaker 2: longer and flatter, with a longer I don't know what
Speaker 2: the technical term for this is the danger zone, the
Speaker 2: space between the two pincers and the insides of the
Speaker 2: pincers on this flatter, longer claw seem to be sharper,
Speaker 2: more like a kind of spiky pair of scissors. And
Speaker 2: then the other claw is shorter in length but bulkier,
Speaker 2: thick with muscle, and the inside edges of its pincers
Speaker 2: have a sort of rounder, larger grain texture, almost pebbled,
Speaker 2: rather than with tiny spines. These claws are commonly referred
Speaker 2: to as the cutter and the crusher, respectively. I think
Speaker 2: the cutter is sometimes called the pincher also, But yeah,
Speaker 2: they are what they sound like, the cutter and the crusher.
Speaker 2: So what's going on? Why the two different claws on
Speaker 2: the same lobster? How does a lobster end up with
Speaker 2: two very different claws and what are they for? Well,
Speaker 2: to answer this question, I was reading what I thought
Speaker 2: was a really interesting older article in American Scientist magazine.
Speaker 2: So this is from nineteen eighty nine by an author
Speaker 2: named C. K. Govind who was a professor of zoology
Speaker 2: at the University of Toronto, and it's called asymmetry in
Speaker 2: Lobster claws. Seems like a lot of Govin's research focused
Speaker 2: on crustaceans, and so Govin begins by pointing out a
Speaker 2: number of different examples of asymmetry and animals. He talks
Speaker 2: about lateral dominance or handedness in humans and even mentions
Speaker 2: I thought this was interesting. In some songbirds, such as canaries,
Speaker 2: you have bilateral asymmetry in their singing apparatus. Song production
Speaker 2: seems to be centered on structures in the left half
Speaker 2: of the syrinx, And so when you see asymmetries like this,
Speaker 2: you can ask all kinds of questions about them. But
Speaker 2: one thing is that you might just assume them to
Speaker 2: be permanent, fixed features of anatomy, hard coded by genes
Speaker 2: and express through early development. But it's interesting that there
Speaker 2: are some cases where asymmetry in an animal's body seems
Speaker 2: to be reversible. Just for one example, In some cases
Speaker 2: of lateral dominance, damage to the dominant side of the
Speaker 2: brain or body can cause the non dominant side to
Speaker 2: assume some functionality previous localized to the side that has
Speaker 2: now been incapacitated, and this can lead us to wonder
Speaker 2: how do these asymmetries develop in the first place. So
Speaker 2: Govind argues that by examining the lobster, and this is
Speaker 2: the American lobster Homarus americanas we can see an example
Speaker 2: of a symmetry emerging not purely as a result of
Speaker 2: genetic coating, but actually as a result of how the
Speaker 2: lobster interacts with its environment during a crucial early period.
Speaker 2: And this is what brings us back to the crusher
Speaker 2: claw and the cutter claw. So I want to read
Speaker 2: from Govin's introduction here quote. As any self respecting gourmet knows,
Speaker 2: the paired claws of the American lobster have decidedly different morphologies.
Speaker 2: One claw, called the crusher or major claw, is short, stout,
Speaker 2: and heavy, with molar like teeth on its biting surface.
Speaker 2: I think that's a good comparison, molar like teeth. It's
Speaker 2: the pebbles are like your back teeth. It's hard to
Speaker 2: imagine them snipping something off. Instead, it's like they would
Speaker 2: sort of grab hold of it and be able to
Speaker 2: smash it real good.
Speaker 1: Yeah. When I'm looking at a picture of this, I
Speaker 1: can't help but imagine the lobster putting on a puppet
Speaker 1: show with just its pincher and its crusher and each
Speaker 1: of them have you know, different characters like like hey
Speaker 1: on the crutcher, Hey on the pincher, and they interact.
Speaker 2: You know, definitely the cutter claw has the higher voice.
Speaker 1: Yeah.
Speaker 2: Yeah, Let's say if they're street fighter characters, crusher claw
Speaker 2: is zangief and cutter claw is is what maybe maybe embison?
Speaker 1: Yeah yeah maybe so longer does.
Speaker 2: That cheap spinning move? Yeah? Okay, So anyway, so that's
Speaker 2: what that is. That that's the molar teeth on the
Speaker 2: biting surface. But then, to continue the quote, the other
Speaker 2: called the cutter or minor claw is long and slender
Speaker 2: with incisor like teeth or your incisors are your front teeth,
Speaker 2: the ones that you use to bite off things, you know,
Speaker 2: not to mash them up, but to separate them from
Speaker 2: what they're originally stuck to and pull them into your mouth.
Speaker 2: They're for cutting. So what Govind writes is quote what
Speaker 2: the gourmet might may not know, and what lobstermen know
Speaker 2: painfully well, is that the cutter claw can give a quick,
Speaker 2: nasty pinch. Indeed, it's dactyl, meaning the part of the
Speaker 2: claw that moves, the closing part can close against the
Speaker 2: opposing polyx within twenty milliseconds, which is several times faster
Speaker 2: than any human reflex. In contrast, the crusher claw closes
Speaker 2: very slowly, but with enough force to crack open the
Speaker 2: shells of oysters, muscles, and other bivalves. And it's true,
Speaker 2: molluscs such as muscles are a big source of food
Speaker 2: prey for the American lobster. So it crawls along the
Speaker 2: ocean floor in its adult phase, and what does it eat. Well,
Speaker 2: it might eat some worms of various types and stuff,
Speaker 2: but it's really going to be looking for mollusks such
Speaker 2: as muscles. It wants to crack those shells open and
Speaker 2: get that meat inside. Also, while we're mentioning anatomy, this
Speaker 2: is unrelated, but I just have to say American lobsters
Speaker 2: pe out of their faces. You kind of can't bring
Speaker 2: lobsters up without mentioning that they face pee, and they
Speaker 2: face peece specifically at each other, whether it's a mate
Speaker 2: or rival. So lobster sees another lobster, they're probably going
Speaker 2: to be peeing out of their faces at them. Though,
Speaker 2: is best I can tell. The face peeing is symmetrical.
Speaker 1: Okay, well that's good to know, But coming.
Speaker 2: Back to the claws. So the difference in the speed
Speaker 2: of pinching between the two claws is evidence of an
Speaker 2: underlying difference, and not just the shape of the claw,
Speaker 2: but its muscular composition. These claws have different types of
Speaker 2: muscle in them. About ninety percent of the space of
Speaker 2: a lobster's claw is taken up by the closer muscle.
Speaker 2: This is the muscle responsible for bringing the pincers together.
Speaker 2: Only a relatively tiny muscle is devoted to opening the claw,
Speaker 2: which is why a lobster might be able to pinch
Speaker 2: with massive force, but a simple rubber band can render
Speaker 2: its claw harmless by holding it closed. It has way
Speaker 2: more strength for closing than it does for opening.
Speaker 1: I think that's a great point.
Speaker 2: Yeah, I didn't double check this, but I just remembered
Speaker 2: hearing a fact that may or may not be true
Speaker 2: about alligator and crocodilian jaws like that when I was
Speaker 2: a kid. That you know, So they can close their
Speaker 2: jaws with massive force, but you can actually quite easily
Speaker 2: hold their jaws together and they can't open them back up.
Speaker 1: Oh, so this would be the secret of the feet
Speaker 1: of the crocodile or alligator wrestler. Yes, Okay, Now coming
Speaker 1: back to the lobster, does that mean that the closer
Speaker 1: muscle is the delicious part? This is like that prize
Speaker 1: sliver of meat from the claw.
Speaker 2: Well, I don't know about relative flavors. The closer would
Speaker 2: be the big one, and the opener is obviously you know,
Speaker 2: it's like ten percent. It's like one ninth the size
Speaker 2: of the closer muscle. So I don't know exactly what
Speaker 2: you're getting. When you have a cooked lobster and you
Speaker 2: pull it out of there and eat it, you probably
Speaker 2: some combination of the two.
Speaker 1: Well, I guess in my experience, like the bigger the
Speaker 1: meat you pull out of a crustacean, like the greater
Speaker 1: the sense of victory. Yeah, And likewise, the more that
Speaker 1: one is picking through the crustacean with and removing tiny
Speaker 1: slivers to consume, the delicious they may be. But the
Speaker 1: more I feel like I'm some sort of like a
Speaker 1: creature stooped on a primordial shore scavenging pieces from a
Speaker 1: dead animal.
Speaker 2: Getting the pieces from the tiny legs and the tiny
Speaker 2: parts makes you feel more like it's the road, you know,
Speaker 2: like looking for seeds or something to eat.
Speaker 1: But pulling out that big piece of claw meat. You
Speaker 1: feel like a king.
Speaker 2: That's right, that's luxury. Okay, So you got these different muscles.
Speaker 2: You got the closer muscle, the opener muscle. What makes
Speaker 2: the difference in the speed of pinching between the crusher
Speaker 2: claw and the cutter claw is the type of muscle
Speaker 2: fiber that the closing muscle is composed of. The cutter
Speaker 2: claw is made of about ninety percent fast muscle fiber,
Speaker 2: which is exactly what it sounds like. It's designed to
Speaker 2: move quickly along with what Govind calls a quote small
Speaker 2: ventral band of slow muscle, whereas the crusher claw is
Speaker 2: almost entirely or not almost, I think is entirely one
Speaker 2: hundred percent slow muscle fiber. So it closes more slowly,
Speaker 2: but can close with incredible force. And as a result,
Speaker 2: cutter snaps fast and sharp. Crusher closes slowly, but but
Speaker 2: it's massive. So you could compare this to handedness in humans,
Speaker 2: but Govind notes that while the majority of humans are
Speaker 2: right handed, the distribution of claws on adult lobsters seems
Speaker 2: equally probable both ways. It's not like the crusher claw
Speaker 2: is always on the left side. It's it's a coin flip.
Speaker 1: Which, which would mean that there's that natural selection is
Speaker 1: not pushing it one way or the other.
Speaker 2: Right, it's not, I mean it's push. It's clearly pushing
Speaker 2: the lobsters to have two different types of claws for
Speaker 2: the asymmetry to exist. But it doesn't seem to matter
Speaker 2: which side is which, at least not in a way
Speaker 2: that's universal across lobsters. It is it is decided by
Speaker 2: each individual lobster in development. So a great question then is, Okay,
Speaker 2: if the bilateral asymmetry is individual to each lobster and
Speaker 2: it's a random coin flip at least from a statistical
Speaker 2: point of view, what causes the change? How does the
Speaker 2: individual lobster's body when it's growing pick which side becomes which. Well,
Speaker 2: we can look at lobster larval development to see this.
Speaker 2: So when they're tiny little things swimming around before they
Speaker 2: become the big lobster, as we recognize, during the early
Speaker 2: larval stages, the claws of the lobster are undifferentiated. They're
Speaker 2: exactly the same. Both claws have what Govind calls quote
Speaker 2: a central band of fast fibers sandwiched dorsally and ventrally
Speaker 2: by slow fibers. Then during the later juvenile stages this
Speaker 2: would be like the fourth and fifth molting stages, there
Speaker 2: begins to be some variability in the amount of slow
Speaker 2: and fast fibers in each claw. But then the changes
Speaker 2: really start to become apparent during the sixth stage of molting. Quote,
Speaker 2: when the putative crush sure claw becomes slightly shorter and
Speaker 2: stouter with a central molar like tooth, while the putative
Speaker 2: cutter claw remains long and slender with a central incisor
Speaker 2: like tooth. A corresponding asymmetry in the composition of the
Speaker 2: closer muscle also develops. The muscle of the cutter claw
Speaker 2: gradually acquires fast fibers by transforming the slow fibers of
Speaker 2: most of its cross sectional face. The exception is a
Speaker 2: ventral band. The muscle of the crusher claw gradually transforms
Speaker 2: all of its fast fibers to slow fibers. In succeeding
Speaker 2: juvenile development, the paired claw's further diverge toward well defined
Speaker 2: cutter and crusher claws. So the divergence happens sometime in
Speaker 2: the childhood of a lobster, sometime around its fourth and
Speaker 2: fifth molting stages and really starts to appear during the
Speaker 2: sixth molting. But then Govin mentioned something I thought was
Speaker 2: really intriguing, an experiment going all the way back to
Speaker 2: nineteen o eight, way back to a researcher named Victor Immel,
Speaker 2: who found that if you remove one of the lobster's
Speaker 2: claw during the fourth or fifth stage, so you just
Speaker 2: pull that claw off, the claw that is left behind,
Speaker 2: still attached to the lobster, always becomes a crusher claw,
Speaker 2: and meanwhile the animal regenerates a new claw where the
Speaker 2: old one was torn off. A lot of crustaceans can
Speaker 2: do that. It grows a new claw, and the new
Speaker 2: claw always becomes the cutter claw. But this only happens
Speaker 2: if you do it early. So if you pull off
Speaker 2: a lobster's claw after the larval stage, when it's already
Speaker 2: approaching adulthood, when the asymmetry is already beginning to show up,
Speaker 2: the original arrangement stays intact. The claw you pulled off
Speaker 2: will regenerate as whichever type it already was. So this
Speaker 2: seems to show that claw laterality is determined sometime during
Speaker 2: the molting stages of like four to five, and it
Speaker 2: probably won't change after that, so what causes asymmetry to
Speaker 2: become fixed to during this stage in a young law's life?
Speaker 2: And here begins a long, twisting and to my mind
Speaker 2: fascinating journey of experiments trying to pin down how this happens.
Speaker 2: Most of these experiments Govind himself was in some way
Speaker 2: directly involved in, and for the sake of brevity, I'm
Speaker 2: going to gloss over some details in this section, but
Speaker 2: you can look up the article for yourself if you
Speaker 2: want the more zoomed in version with all the details
Speaker 2: and citations. I'll try to give a more sky level view. So,
Speaker 2: first of all, Govin and colleagues notice some things we
Speaker 2: already know leading into these experiments. One is that the
Speaker 2: triggers for developing different claws must be randomly distributed under
Speaker 2: normal conditions to explain the random distribution of claws in
Speaker 2: the wild, but not random once a claw is lost.
Speaker 2: And this naturally suggested something about use the way the
Speaker 2: claw is used. When one claw is pulled off and
Speaker 2: has to grow back and new, it isn't getting used,
Speaker 2: so the remaining cl law is getting used, and maybe
Speaker 2: it's something about getting used more that makes a claw
Speaker 2: into a crusher. This would align with the fact that
Speaker 2: the juvenile stage in which the claws become asymmetrical also
Speaker 2: coincides with a change in the lobster's lifestyle. So when
Speaker 2: the claws start to become asymmetrical is around the time
Speaker 2: when lobsters transition from swimming amongst the plankton to living
Speaker 2: on the ocean floor and crawling around on the substrate
Speaker 2: and burrowing in the substrate substrate meaning the stuff that
Speaker 2: lines the ocean floor. Now, some research had been done
Speaker 2: which found that if you take a bunch of lobsters
Speaker 2: and you raise them in smooth plastic trays environments with
Speaker 2: no stuff to mess with on the bottom of the water,
Speaker 2: lobsters do not, in fact develop crusher claws at all.
Speaker 2: In smooth environments. They just get symmetrically paired cutter claws,
Speaker 2: two cutters exactly the same. But if you put a
Speaker 2: lobster that's already reached the stage where its claws split
Speaker 2: into different types into a smooth environment, it keeps its
Speaker 2: crusher claw, So again it gets fixed sometime early on.
Speaker 1: All right, So it seems like it's the environment that
Speaker 1: is key here, right.
Speaker 2: It seems to be something about the texture of the
Speaker 2: environment at the right stage that causes crusher claws to emerge.
Speaker 2: So here's a new experiment. You raise lobsters in a
Speaker 2: smooth plastic environment versus one scattered with pieces of broken
Speaker 2: oyster shells? Does a lobster grow up differently with different
Speaker 2: distributions of claws on smooth plastic versus oyster chips? And
Speaker 2: the results were oyster shells give you normal asymmetrical lobsters
Speaker 2: with a crusher and a cutter. The smooth, no substrate
Speaker 2: gives you a pair of identical cutters. This was fascinating
Speaker 2: to me. Okay, so it's like what it's crawling around
Speaker 2: on determines how its claws develop. So they wanted to
Speaker 2: refine this answer further. Why is this it? Is this
Speaker 2: result something about oyster chips in particular, or could it
Speaker 2: be any substrate. So they tried the experiment again, but
Speaker 2: instead of oyster shells, they used different stuff. They used gravel,
Speaker 2: they used mud with debris, and they even used tanks
Speaker 2: with plastic shirt buttons and all of these produced normal
Speaker 2: lobsters with one crusher, one cutter normally randomly distributed crusher claws,
Speaker 2: and in a control they had a flat smooth substrate
Speaker 2: that had been painted to look like oyster chips, but
Speaker 2: it did not but did not have any actual stuff
Speaker 2: to crawl or burrow around in, and this did not
Speaker 2: facilitate differentiation. So on the one that was flat and
Speaker 2: smooth but painted, it still produced identical symmetrical cutters. Another
Speaker 2: experiment to refine this what about lobsters in smooth plastic trays,
Speaker 2: but putting them together instead of by themselves. This plays
Speaker 2: on the fact that lobsters are not very friendly to
Speaker 2: each other. They are aggressive and tend to fight each other,
Speaker 2: and typically when they were put in together, they would
Speaker 2: duel a bit and one of the lobsters would often
Speaker 2: get one or both claws removed in battle. Yeah, I know,
Speaker 2: this is kind of going into bug fights territory, but
Speaker 2: the lobster. So what they found was the lobster with
Speaker 2: both claws left would split like in the wild with
Speaker 2: an asymmetrical distribution with one crusher claw. So if there
Speaker 2: is no substrate, if you don't have any mud or
Speaker 2: oyster chips to root around and fighting will also do
Speaker 2: to split your claws into different types.
Speaker 1: Okay, that this makes sense. It's about having It would
Speaker 1: seem to have something to do with the sorts of
Speaker 1: things you're encountering with your claws, be it chunks of
Speaker 1: oysters or the hard body of another lobster combatant.
Speaker 2: Right, it seems to have something to do with doing
Speaker 2: something with the claws that produces one crusher of the two.
Speaker 2: Oh and as a control I thought this is also interesting.
Speaker 2: They're like, well, we want to make sure it's not
Speaker 2: just the appearance of another lobster that causes a crusher
Speaker 2: to develop. So they tried one with a smooth container
Speaker 2: but a mirror, so that if the lobster could see
Speaker 2: its reflection, would this make a differentiate But nope, heerio,
Speaker 2: you just got two cutters.
Speaker 1: It's got to be the tactile experience.
Speaker 2: Okay, yeah, so so far this is all lining up
Speaker 2: with the hypothesis that it's something about the claw getting
Speaker 2: used more that caused them to split and one to
Speaker 2: become a crusher. So they tried a new experiment with
Speaker 2: the hypothesis that if you put a lobster in a
Speaker 2: normal environment with a substrate, but you prevent only one
Speaker 2: of a lobster's claws from opening and closing, that's going
Speaker 2: to get less use. That's going to turn into the
Speaker 2: cutter claw and the other one will become a crusher. Okay,
Speaker 2: So they tried this with various methods, such as holding
Speaker 2: one claw shut with a rubber band or with a
Speaker 2: dab of glue, and they found, to their surprise, this
Speaker 2: did not produce the result they expected. They thought, if
Speaker 2: a claw can't open and close, that the other one's
Speaker 2: going to become the crusher. But no, Instead, with these lobsters,
Speaker 2: you still got random lateralization. In some the right became
Speaker 2: a crusher and some of the left became a crusher. Wow.
Speaker 1: So it because that was going to be my guess
Speaker 1: that it depends on how that particular claw is being used,
Speaker 1: But we see this random distribution occurring even when that
Speaker 1: one claw is, say, rubber banded shut right.
Speaker 2: So here they were like, well, maybe it has something
Speaker 2: to do with the claw being used, but not with
Speaker 2: it being able to open and close, and maybe it's
Speaker 2: something else. So from here they proceeded to a number
Speaker 2: of different anatomical experiments and to try to quickly summarize
Speaker 2: their findings. First of all, they found if you cut
Speaker 2: a tendon, preventing only one of a lobster's claws from
Speaker 2: opening or closing. This does stop it from becoming a crusher,
Speaker 2: possibly by preventing fast muscle fibers from transforming into slow
Speaker 2: muscle fibers. And they reason from this maybe it could
Speaker 2: be a result of severing reflexive nerve pathways in the process.
Speaker 2: So they tried to see what happened if you sever
Speaker 2: a nerve running from the claw to the sort of
Speaker 2: central nervous system control for the claw. A lobster's nervous
Speaker 2: system is not exactly like ours. They don't just have
Speaker 2: one central brain leading out to everything. They've got ganglia,
Speaker 2: you know, the centralized nodes sort of within the nervous system.
Speaker 2: So you would want to be severing the reflexive fiber
Speaker 2: running from the claw to the ganglia. Unfortunately, when they
Speaker 2: did this by severing that nerve somewhere in there, it
Speaker 2: almost always resulted from the lobsters after they came out
Speaker 2: of anesthesia, they would perform what's known as autotomy on themselves,
Speaker 2: So the lobster's nerve is cut, and then the lobster says, okay,
Speaker 2: don't need this claw anymore, and they would sever their
Speaker 2: own arm and grow a new one. This is a
Speaker 2: standard reaction. Actually of crustaceans, when a limb is trapped
Speaker 2: or damaged, they just cut it off and grow a
Speaker 2: new one, which is a fantastic thing to be able
Speaker 2: to do. And apparently severing the nerve within the claw
Speaker 2: seemed to trigger something in the lobster that suggested it
Speaker 2: needed to do that. That causes the behavior in the lobster.
Speaker 2: It says, something's wrong with this lamb. I'm removing it
Speaker 2: and I'll just get a new one.
Speaker 1: Fun tie in for tomorrow's Weird House Cinema episode.
Speaker 2: Oh brilliant. I didn't even make that connection. Yeah, So
Speaker 2: instead the researchers tried to incapacitate the part of the
Speaker 2: central nervous system leading to the clause, so incapacitating it
Speaker 2: more centrally to the body. This did work as expected.
Speaker 2: It did prevent the claw in question from becoming a crusher.
Speaker 2: So it has it must have something to do with
Speaker 2: nerve inputs from the claw that causes the asymmetry to develop.
Speaker 2: And they tested this with some target exercise regimes. Actually,
Speaker 2: and here I thought this was great. So I just
Speaker 2: wanted to read from the article. So Govind writes quote
Speaker 2: in an inspired moment we thought of enhancing activity by
Speaker 2: exercising one of the paired claws in a substrate free environment.
Speaker 2: The lobster was held and its claw law gently stroked
Speaker 2: with a small paint brush so that the bristles were
Speaker 2: gripped several times during a sixty second session. This regimen
Speaker 2: was repeated three times daily at five hour intervals through
Speaker 2: the entire fourth and fifth stages, the molting stages, that is,
Speaker 2: for about a month. A control group of lobsters was
Speaker 2: reared under identical conditions, including being handled but not exercised.
Speaker 2: While the lobsters in the control group developed paired cutter claws,
Speaker 2: the experimental lobsters developed a crusher on the exercised left side.
Speaker 2: The fact that the only perceived difference between the two
Speaker 2: groups of lobsters was the amount of exercise strengthened our
Speaker 2: belief that some minimal level of reflex activity in the
Speaker 2: claw is probably needed to differentiate a crusher claw. However,
Speaker 2: then they said, okay, what happens if we do the
Speaker 2: exact same thing, but we exercise both claws with the
Speaker 2: paint brush, will this give us two crusher claws, which is,
Speaker 2: by the way, something that we basically never find in nature.
Speaker 2: I think they cite one example of a lobster that
Speaker 2: had two external morphologies looking like crusher claws, but the
Speaker 2: muscles inside did not match. So that pretty much never
Speaker 2: happens in nature, and they found no. In fact, their
Speaker 2: experiment could not produce two crusher claws either. In fact,
Speaker 2: it was not only not able to produce two crusher claws,
Speaker 2: it gave them just the opposite. Whereas tickling only one
Speaker 2: claw with a paint brush and making the claw close
Speaker 2: around the paint brush by reflex that made that the
Speaker 2: crusher boss claw. Tickling both claws but the paint brush
Speaker 2: equally turned the lobster into a symmetrical beast with two
Speaker 2: identical cutter claws only. Huh.
Speaker 1: So, if there are any chefs out there who believe
Speaker 1: that the crusher claw is superior, and they're looking for
Speaker 1: ways to create the pure crusher lobster, it thus far
Speaker 1: seemsossible to pull off.
Speaker 2: It does not seem possible, though, though I will say
Speaker 2: this is an older article, I've not looked into subsequent
Speaker 2: attempts to create two crusher claw lobsters, but I doubt it.
Speaker 2: I don't think you can do that. That's just not
Speaker 2: part of the lobster's destiny, not part of its genetic destiny.
Speaker 2: So a lot of this seems to add up to
Speaker 2: show that it's not just stimulation or use of a
Speaker 2: claw that causes it to become a crusher. But that's
Speaker 2: something that seems to be important, is that it is
Speaker 2: differential use, which is somehow weighed or compared internally by
Speaker 2: the lobster's nervous system or ganglia, and the side that
Speaker 2: gets more use becomes a crusher. So it's not you
Speaker 2: can't exercise both sides and make them two crushers. If
Speaker 2: you do them equally, you get no crushers. You've got
Speaker 2: to get one side getting more stimulation or reflex exercise
Speaker 2: than the other one, which suggests that there is I
Speaker 2: don't know that there is some kind of internal comparison
Speaker 2: module going on in the nervous system. And so Govin concludes,
Speaker 2: quote in nature, as in the laboratory, initial use or
Speaker 2: contact of one claw with a substrate sets in motion
Speaker 2: an increasingly greater activity on that side. The greater neural
Speaker 2: input of that side determines in the central nervous system
Speaker 2: its fate as a crusher, and at the same time
Speaker 2: inhibits the opposite side from ever becoming a crusher, and
Speaker 2: Govin ends up using an analogy of a teeter totter.
Speaker 2: I thought this was funny, actual illustrations of crab claws
Speaker 2: on a playground teeter totter. So he shows, okay, you
Speaker 2: can have a balance where one side is a crusher
Speaker 2: and one's a cutter, and so cutter is up in
Speaker 2: the air, crusher is down. You can have balanced with
Speaker 2: both sides straight. You know, they're both hanging up in
Speaker 2: the air and they're both cutter claws. But if you
Speaker 2: tried to have two crusher claws, something doesn't work there.
Speaker 2: It's like the pole in the middle of the teeter
Speaker 2: totter will break, it won't support it. So whatever the
Speaker 2: exact calculus of experience in the nervous system leading to
Speaker 2: claw development, these experiments seem to make it clear that
Speaker 2: claw asymmetry is a prime example of what Govind calls
Speaker 2: quote experience modulating inherent programs, and this seems to be
Speaker 2: the underlying principle behind much of how any organisms body
Speaker 2: is formed and how it behaves, which kind of cuts
Speaker 2: through a lot of naive all or nothing nature nurture
Speaker 2: reasoning like much of what an animal is is necessarily
Speaker 2: a product of both it's genetically innate materials and programs
Speaker 2: that are the starting sort of the building blocks, and
Speaker 2: then life itself, the experience of living in an environment
Speaker 2: and the experiences that the organism has those determine how
Speaker 2: those innate materials and programs are expressed, leading to vastly
Speaker 2: different outcomes, even completely opposite outcomes, flipping the sides on
Speaker 2: which the crusher claw exists. So in the case of
Speaker 2: a lobster, the metaphor is kind of profound.
Speaker 4: You know.
Speaker 2: It starts with potential for a crusher on the right,
Speaker 2: a crusher on the left, or no crusher at all,
Speaker 2: but probably not two crushers, and then eventually the fixed
Speaker 2: form of its adult body depends on some early experience,
Speaker 2: whether and how it digs around in oyster shell chips
Speaker 2: or even shirt buttons, some early experience, some experience of
Speaker 2: moving one claw more than the other, or getting having
Speaker 2: some kind of sensory input causing reflexes. Maybe something that
Speaker 2: is information fed into the central ganglia through the nerves
Speaker 2: and the claws determines Okay, this claw is getting more
Speaker 2: use than the other one. That's the one that's going
Speaker 2: to be the crusher for the rest of my life.
Speaker 1: Fascinating. Now. I had to look this up real quick
Speaker 1: to see if there was any information about the taste
Speaker 1: debate between these two claws. I did find an article.
Speaker 1: This is a two thousand and eight Associated Press article
Speaker 1: titled the Great Lobster Debate, Claws Versus Tails. As the
Speaker 1: title implies, this is mostly about taste differences between the
Speaker 1: claws of a lobster and the tails of a lobster,
Speaker 1: and it points out that that of the two claws,
Speaker 1: the crusher claw generally is tougher than the pincer claw.
Speaker 1: It doesn't get into the taste differences between the two,
Speaker 1: but it does point out that the tail, on the
Speaker 1: other hand, is meteor and more flavorful, in part due
Speaker 1: to the fact that or in large part due to
Speaker 1: the fact that the tail is used more the tail
Speaker 1: muscle is used more than the claw muscles. And this
Speaker 1: is cited to Brian Beal, a lobster expert and professor
Speaker 1: at the University of Maine.
Speaker 2: How many how many lobsters did he have to eat
Speaker 2: for that experiment?
Speaker 1: But it does make me think that maybe, certainly, if
Speaker 1: you're talking about claw vers's claw. It's probably going to
Speaker 1: be a matter of personal preference, but it could be
Speaker 1: wrong on that. Perhaps lobster are aficionados out there have
Speaker 1: some input on this. Maybe there's one claw they find
Speaker 1: themselves going to before the other. Maybe there are even
Speaker 1: certain dishes where oh, well, you only want to use
Speaker 1: this claw for this dish, and then you want to
Speaker 1: save your pincher or save your crusher for some other dish.
Speaker 1: I don't know.
Speaker 2: Well, wait, which one did you say was the one
Speaker 2: that was usually tougher? Was it the crusher?
Speaker 1: This article says the crusher claw, the larger of the
Speaker 1: two used to crush things generally, is tougher than the
Speaker 1: pincer claw.
Speaker 2: To make sense apart, Yeah, so that the crusher claw
Speaker 2: is the slow muscle fiber and the pincher is the
Speaker 2: fast muscle fiber. And oh, I hesitate to say this
Speaker 2: because they may but they may not be comparable at all.
Speaker 2: I'm not sure how the analogy goes across different you know,
Speaker 2: fi love of animal life, but I mean, if you
Speaker 2: think about a chicken, like the breast meat is generally
Speaker 2: the fast muscle fiber and the dark meat is generally
Speaker 2: the slow muscle fiber, and that translates to different types
Speaker 2: of taste and texture within the meat. Like generally chefs
Speaker 2: would cook dark meat to a higher temperature because it
Speaker 2: has more sort of that needs to render out of
Speaker 2: it to render it tender.
Speaker 1: Yeah, this article indicates that generally speaking, your lobster tail,
Speaker 1: that's what's going to get deep fried or whatever, while
Speaker 1: the claw meat is going to be more tender, and
Speaker 1: that's what's going to go into your lobster rolls and
Speaker 1: your lobster club sandwiches.
Speaker 2: I'm sure there are people who want to fight about
Speaker 2: whether you're supposed to deep fry a lobster or not.
Speaker 2: We're not here to settle that debate. But anyway, I
Speaker 2: found this little research journey fascinating trying to pin down
Speaker 2: how and why this happens in a lobster, and it
Speaker 2: also just seems like somehow rich for metaphor.
Speaker 1: Yeah, yeah, this is fascinating. I don't know that I'd
Speaker 1: really given much thought to this, in part because there
Speaker 1: are certainly clawed crustaceans out there that are more pronounced
Speaker 1: in their asymmetry, and I think we're going to get
Speaker 1: into those more in the third episode in this series.
Speaker 2: Yes, there are some crustaceans, specifically some crowd that take
Speaker 2: claw asymmetry to a ridiculous extreme. That we'll save those
Speaker 2: for next time.
Speaker 1: All right, So sticking to the aquatic world here, I
Speaker 1: thought i'd go in another direction that I imagine a lot
Speaker 1: of people were thinking about as we were talking about asymmetry,
Speaker 1: and particularly in the last episode, you know we were
Speaker 1: talking about the blowhole of the toothed whale migrating up
Speaker 1: to the top of the head. Well, we have to
Speaker 1: talk about the flatfish. There are some eight hundred species
Speaker 1: of flatfish in global waters, and probably one of the
Speaker 1: most famous groups here is the flounder. And if you
Speaker 1: haven't seen a flounder, do look up a picture. The
Speaker 1: pictures are. A picture of a flounder is always amusing
Speaker 1: or unsettling. Basically, what has occurred here is that the
Speaker 1: flatfish's eye left or right, depending on the variety of fish,
Speaker 1: has migrated to one side of its body to facilitate
Speaker 1: a sideways life in which it camouflages itself against the
Speaker 1: ocean floor, like basically living on the floor, kind of
Speaker 1: like array or something would live on the floor. But
Speaker 1: it acquires its flatness by being sideways. Both eyes are
Speaker 1: on the side facing up.
Speaker 2: This looks hilarious, and I think it's different, unless I'm
Speaker 2: forgetting one. I think this is different than any of
Speaker 2: the other asymmetry examples we've talked about before, because I
Speaker 2: think all of the other ones have been cases where
Speaker 2: there is something that's originally symmetrical on both sides of
Speaker 2: the body, and then they develop in different ways, like
Speaker 2: one you know, maybe one hole opens and the other
Speaker 2: one closes, or one claw grows bigger and with a
Speaker 2: different shapes than the other, different muscle fibers or something
Speaker 2: like that. They just develop in different ways or two
Speaker 2: different extents. This is a case of a symmetry where
Speaker 2: something that was originally symmetrical has one of the two
Speaker 2: elements migrate to the opposite side, so they're actually switching
Speaker 2: sides instead of just like one growing bigger than the
Speaker 2: other or something.
Speaker 3: Yeah.
Speaker 1: Yeah, it's it's super weird looking. And one of the
Speaker 1: telling things about these fish is that you can also
Speaker 1: look at larval flounders, for example, and see eyes on
Speaker 1: both sides of the larva's head. So it's only as
Speaker 1: they develop and mature that the eyes move to the
Speaker 1: other side. Also, like with some of the whale examples
Speaker 1: we were looking at, you can look back in the
Speaker 1: fossil record and make out a halfway point in the evolution. Particularly,
Speaker 1: you can look at the fifty million year old fossil
Speaker 1: of Anthistium, which has an eye that has migrated to
Speaker 1: the top of the head, but no farther.
Speaker 2: Oh that's interesting. So it would have like it's evolved
Speaker 2: enough that it has one eye pointing up and another
Speaker 2: one sort of pointing perpendicular to that right right, Okay.
Speaker 1: It has not reached its final form. I guess you
Speaker 1: would say. Was reading an article from two thousand and
Speaker 1: eight in the journal Nature by A. Matt Friedman titled
Speaker 1: the evolutionary origin of flatfish asymmetry, and he points out
Speaker 1: that Eocene fossil evidence here with Amphistium and another species,
Speaker 1: heteronic ties, both demonstrate the intermediate form.
Speaker 2: I mean, I guess isaat right angles is better than
Speaker 2: one eye just looking down in the dirt.
Speaker 1: Yeah, yeah, but it's it's again. This one makes me
Speaker 1: think back to the cock eyed squid. It makes me
Speaker 1: think of just some of the strange challenges of aquatic
Speaker 1: life in general that lead to these adjustments in a
Speaker 1: creature's form. It's so fascinating.
Speaker 2: Yeah.
Speaker 1: Yeah, And of course, well one might ask, well, you know,
Speaker 1: why don't we see more examples of things like this
Speaker 1: in the surface world. And I think the answer to
Speaker 1: that is we do. You know, we talked maybe not
Speaker 1: in so much in terms of asymmetrical solutions, but in
Speaker 1: terms of like eyes moving with the evolution of a
Speaker 1: particular species. I mean, we talked about, we've talked about
Speaker 1: on the show, the difference between the position of eyes
Speaker 1: on a herbivore versus the eyes on a predator. You know,
Speaker 1: do you need your eyes in a position where you
Speaker 1: can basically see all around you as much as possible
Speaker 1: at a given time, or do you need those things
Speaker 1: hyper focused on the thing that's in front of you?
Speaker 1: You know, these are positions that are reached via evolution.
Speaker 2: Yeah, and actually, to take that even further though, this
Speaker 2: has less to do with the placement of the eyes,
Speaker 2: but more about the shapes of the actual eyeballs themselves.
Speaker 2: You know, we talked not too long ago about research
Speaker 2: even finding differences in common eye shapes based on whether
Speaker 2: a predator is like is an active predator or an
Speaker 2: ambush predator you know that tends to specialize for different
Speaker 2: types of vision, Like do you need to have really
Speaker 2: good vision for estimating the distance needed for one pouncing jump,
Speaker 2: or do you need the kind of vision needed for
Speaker 2: chasing over a period of time.
Speaker 1: Yeah, yeah, exactly. So that's a fun example that I
Speaker 1: just had to bring up. But I have another one here,
Speaker 1: and this is another famous example of asymmetry, and this
Speaker 1: time we are dealing with surface species and surface creatures.
Speaker 1: And it's also an interesting example because it's an example
Speaker 1: of a symmetry leading to more asymmetry. What happens when
Speaker 1: an asymmetrical creature is your preferred prey, Perhaps you become
Speaker 1: more asymmetrical in order to take advantage of it.
Speaker 2: Oh that's interesting. So you'd imagine, like I'm just making
Speaker 2: this up, but if you're fighting some kind of giant
Speaker 2: lobster and one of its claws is bigger and more
Speaker 2: dangerous than the other, if over evolutionary time, your species
Speaker 2: develops i don't know, tougher skin or defenses on the
Speaker 2: side that matches the more dangerous lobster.
Speaker 1: Claw, Yeah, assuming there's some consistency in which side of
Speaker 1: the giant lobster of the money claws on.
Speaker 2: That's true. I guess if it was the American lobster
Speaker 2: would be random. So you're just out of luck there.
Speaker 1: Yeah, but in this case we're dealing talking about the food. First,
Speaker 1: we're dealing with snails, and snails are obviously asymmetrical, possessing
Speaker 1: either clockwise or counterclockwise spiraling shells, and as as a
Speaker 1: side note, slugs are also asymmetrical. Slugs, of course, are
Speaker 1: evolutionarily speaking, they are snails that no longer need to
Speaker 1: carry their homes with them, have put that sort of
Speaker 1: lifestyle behind them, but they really retain the asymmetry.
Speaker 2: Wow, I did not know this. So if I understand right,
Speaker 2: you're saying that the slugs evolved from ancestral snails, they
Speaker 2: evolved from creatures that did have shells, and they evolved
Speaker 2: to lose them to internalize them.
Speaker 1: Yeah. We cover this on an old episode of Stuff
Speaker 1: to Blow your Mind many years back, and so some
Speaker 1: of the details are a bit foggy, but yeah, this
Speaker 1: is the basic story of slugs and snails. And by
Speaker 1: the way, if you look at a slug, you can
Speaker 1: still you can visually mark the asymmetry if you look
Speaker 1: for a particular it looks like a little circular feature,
Speaker 1: a little hole or orifice on their body that is
Speaker 1: the Numa stone. And yeah, it's on one side as
Speaker 1: opposed to the other.
Speaker 2: That's really cool because that's another case where it's like,
Speaker 2: I don't know, just imagining evolution operating in a direction
Speaker 2: opposite to what you would have just naively assumed. It's
Speaker 2: like knowing that whales evolved from mammals that used to
Speaker 2: be land walkers, you know, the four quadrupedal land mammals
Speaker 2: spent more and more time and water and eventually became
Speaker 2: fully aquatic. So here these would be not that slugs
Speaker 2: evolved to gain shells, but that snails evolved in some
Speaker 2: cases to lose their shells.
Speaker 1: Yeah. I mean, like we've covered time and time again,
Speaker 1: nature is flexible when it comes to evolution. The card
Speaker 1: is always subject to change. The card will change, and
Speaker 1: it's the species that evolved in sells into a corner
Speaker 1: sometimes that find it the hardest to survive long term.
Speaker 2: Okay, So in modern snails and slugs, you've got this asymmetry,
Speaker 2: You've got some part of their biology having a kind
Speaker 2: of clockwise or counterclockwise component, and this would of course,
Speaker 2: be of relevance to any kind of creature that interacts regularly,
Speaker 2: especially with the snail that's got a hard external part,
Speaker 2: that's got this clockwise or counterclockwise.
Speaker 1: Shell right, and that brings us to a species of
Speaker 1: snake known as Awasaki's snail eater also known as Awasaki's
Speaker 1: slug snake, and these are found in the Yayama Islands
Speaker 1: of Japan, and they specialize in eating snails, and they
Speaker 1: have specialized jaw structures that enable them to prey on clockwise,
Speaker 1: spiraling or dexterraal snails. However, as a result, they have
Speaker 1: a harder time preying on counterclockwise or sinestral snails. Soasically,
Speaker 1: the way this works out is the snake's mandibles have
Speaker 1: evolved for extracting snail bodies from their shells, and this
Speaker 1: evolved independently, apparently in at least three subfamilies, according to
Speaker 1: Hoso and Hori, writing in The Herpetological Review in two
Speaker 1: thousand and six, the snake inserts its mandibles into the
Speaker 1: snail's aperture and moves each mandible forward and back to
Speaker 1: extract the body. And these two individuals Hoso and Horri,
Speaker 1: they've written several papers on the snake. If you look
Speaker 1: up Ilasaki Snail Leader, you'll all often or always find
Speaker 1: these researchers involved, including a two thousand and seven paper
Speaker 1: titled right handed Snakes Convergent evolution of asymmetry for functional specialization.
Speaker 2: This is one where you should look up a picture
Speaker 2: if you can. The one I'm looking at now, Rob
Speaker 2: that you supplied has the snake biting onto the snail shell,
Speaker 2: and it's got its upper jaw position on the outside
Speaker 2: of the shell and its lower jaw. I guess that's
Speaker 2: the mandible reaching in underneath the tube of the shell.
Speaker 2: So the lower jaw is what's getting inside.
Speaker 1: Yeah, yeah, And just looking at the pigure it can
Speaker 1: be kind of hard to work out exactly what's going on.
Speaker 1: So I want to read a quote here from this
Speaker 1: two thousand and seven paper. They right. We found that
Speaker 1: snakes in the subfamily Peritinae, except for non snail eating specialists,
Speaker 1: have more teeth on the right mandible than the left.
Speaker 1: In feeding experiments, a snail eating specialist pere Iwasaki, completed
Speaker 1: extracting a dextraal soft body faster with fewer mandible retractions
Speaker 1: than a sinestral body. The snakes failed in holding and
Speaker 1: dropped sinnestral snails more often owing to behavioral asymmetry when striking.
Speaker 2: Wow, so it's been preying on these snails so long
Speaker 2: that it's specialized for having one side of its mouth
Speaker 2: ready to get at a certain side of the tube
Speaker 2: of the snail's shell. And if it attacks a snail
Speaker 2: of the opposite handedness in its spiral, it's going to
Speaker 2: be at a real disadvantage.
Speaker 1: Exactly. Yeah. So again a fascinating example of asymmetry leading
Speaker 1: to more asymmetry in the food chain.
Speaker 2: I'm so scared that at some point here I've said
Speaker 2: snail when I'm at snake and vice versa. I apology,
Speaker 2: I apology, I apology if I did that.
Speaker 1: So anyway, Yeah, definitely look up images of the snakes,
Speaker 1: especially if you find an image of it actually feeding
Speaker 1: on a snailshell. All right, Well, we're going to go
Speaker 1: ahead and cap this one off right here, but we
Speaker 1: will be back. I think it's going to be the
Speaker 1: episode after next in which we return with part three
Speaker 1: in this series, but there will be more creatures of note.
Speaker 1: There will be more fascinating evolution and adaptation, and the
Speaker 1: crabs will finally arrive on the scene, don't they always Yes,
Speaker 1: there's no stopping them in the meantime, if you would
Speaker 1: like to check out other episodes of Stuff to Blow
Speaker 1: Your Mind, our core episodes publish on Tuesdays and Thursdays.
Speaker 1: You can also enjoy, if you like, our listener Mail
Speaker 1: episodes on Mondays, our short form Artifact or Monster Fact
Speaker 1: episodes on Wednesdays and on Fridays. We set aside most
Speaker 1: serious concerns and just talk about a weird film.
Speaker 2: Huge thanks as always to our excellent audio producer Seth
Speaker 2: Nicholas Johnson. If you would like to get in touch
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Speaker 2: to suggest a topic for the future, or just to
Speaker 2: say hello, you can email us at contact at stuff
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