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