Welcome to Stuff to Blow Your Mind production of iHeartRadio.
Hey, welcome to Stuff to Blow Your Mind. My name is Robert.
Lamb and I am Joe McCormick. And today on Stuff to Blow Your Mind, we are going to be talking about an animal. About the horned lizard or Frenosoma, a genus of lizard native to North America, also known as horned toads or horny toads. From what I've been reading, I think the people in the biological sciences prefer the more accurate lizard appellation because they are certainly not toads, though there are reasons for calling them toads, mainly that they look like toads.
Now, we're going to probably try and stick to horned lizard. I'm probably going to say horned lizard because I like using the more antiquated term and it sounds more demonic. But we also might say horny toad, horned toad, horn toad, and so forth. Throughout the episode.
Horned Lizard makes me think learned lizard. You know, doesn't it suggest a kind of wisdom?
Yeah? Yeah, sometimes lizards can appear quite wise, so I buy.
That, And in fact, you might even think about some of the species of horned lizards as especially wise or discerning among the reptile kind, because they, as we get into later in this episode, they have some anti predator strategies that really require snap judgment calls about say what type of predator you're dealing with?
That's right, And I don't know if we'll get into it in this episode or the next, but among the Navajo, among the Dne people, they're sometimes called grandfather so I think there is often that vibe of maybe sort of wisdom and power to them.
Though I have to admit I did come to this topic through more base and if you know us predictable routes. So my window into talking about horned lizards was the fact that for sci fi horror nerds like us, it's alien summer. Would you have.
Oh, yeah, it's been an alien summer for me. We've been chatting about alien movies and the upcoming alien movie. So yeah, there's a lot of excitement in the air.
Yeah, there's a new alien movie coming out in theaters later this week, Alien Romulus. Of course, there's no guarantee ahead of time it's going to be good. I don't think they've even released the critics embargo yet, But I'm just recklessly letting myself get excited regardless. Tempering expectations is for the week.
That's right, Say yes to Xenomorph and then figure the rest out later.
You know, if I'm disappointed, I'm disappointed, It'll be okay. So we've had Aliens on the brain for a few months here, and we've covered a couple of Aliens copycat movies on Weird House Cinema. We'll probably do at least one more. I think that's right.
We also had a seven part Monster Fact series on the various creatures and organisms of the alien universe, with part seven publishing this week.
M hmm. But so we've got all this excitement running through us, and I was looking to find some real world biology to cover that had parallels in a and we've already done a lot of topics along these lines in the past, and the idea of the xenomorph's weaponized blood took hold. So in the Alien movies, if you haven't seen them, the creature in these movies has extremely potent acid for blood, which appears to serve as a
defense strategy. So if you cause injury to one of the xenomorphs, you are likely to get some of its blood on yourself or on your critical infrastructure, such as the inside of your spacecraft hull, and that blood will burn through bodies and space ships alike. So, as observed by the characters in the first movie, there's real danger in injuring the creature. How do you fight it?
That's right. It's also worth pointing out that there is at least some acid fluid as projectile in the xenomorph world. The most, I would say, I guess the key example would be in nineteen seventy nine's Alien the first film, as we see that emergent face hugger seem to use acidic secretions to burn through Caine's helmet in order to
access his face. Now, naturally, given that certain wounds, especially lethal wounds to a Xenomorph, could result in a jet of acidic blood, we could easily classify that as a form of defensive spray. And then in Alien three and Alien Resurrection, the third and fourth movies in the franchise, we actually see Xenomorphs using an offensive acid spray attack, And of course this has also been used to various effect in Alien video games. For ranged enemies, as well
as in alien comic books and so forth. Also worth pointing out that, given our current Mortal Kombat discussions on Weird House Cinema, the acid spit is one of the signature moves of the green clad Ninja reptile.
Is it really a spit because the animation looks to me more like projectile vomit.
I think it depends. At least in the first game. He was in Mortal Kombat too, he would definitely spit. I don't. It was like a kind of a sound over and over again, and I think it got a little more vomity later.
Okay. Now, of course, it's fairly common in the natural world to find animals that produce some kind of toxic defensive fluid that they use to protect themselves against predators or attack prey. But what seemed less common, though perhaps more common than you would think, was that the defensive fluid in question was actually the animal's own blood.
That's right, because part of the logic here, of course, is we tend to think vampire like when we think about an organism's blood. Right, It's part of the prize, It's part of the predator's claim. So broadly, speaking, it would, on the surface anyway, seem illogical to think that a predator could be harmed by the blood of its prey.
But here is where the horned lizard comes in. If you know one thing about the horned lizard, it is probably that these various species of lizards have a defensive adaptation of squirting blood out of their eyes.
That's right. They're kind of internet famous for this, a lot of clips, a lot of animations and videos. I should also add that if you know one thing, you should probably know two things. Also, that they're to some extent horned up right, because right, tall them horned lizards, right.
But while lots of animals are spiky or horned in some way, I would say that the blood squirting out of the eyes is such a shocking behavior, such a bizarre and seemingly rare adaptation, that you would almost have to wonder if it's not real, Like is that something people just made up? Or does that really happen? And according to the author of a book that I'm going to cite in this episode, reports of it have sometimes in the past been dismissed as tall tales. But they're
not tall tales. The horn Blizzard's weaponized blood is absolutely real and it is the subject of some interesting scientific investigation.
So this is going to be really fun to get into now. When we were doing our pre research, though, Joe, you brought up a resource that we've looked to in the past, and that's the California herbs dot com website, where they have a wonderful I mean, it's not just about this, but they have a huge listing of various herp appearances in various films, many of which are very much in the domain of weird house cinema meaning reptiles, yes, yeah, yeah,
for herpetologist cinema files. And they have a list there that you shared with me of horned lizards in movies, and there are a few that I was familiar with, you know, because they're pretty popular films. I think what Outlaw Josie Wales is on there.
Yeah, yeah, but the wldye there are apparently a number of you know, westerns I guess where there are horned lizards, which makes sense because you know, you find a lot of these several of these species are very common in the American Southwest.
But also Jo Roowski's Holy Mountain is included there. His film from nineteen seventy three that does have a very memorable hert scene, though it may contain shots of actual herbs exploded with fireworks, so you know, go into that one with a certain amount of caution. But it's I mean, it's holy mountains, so I'd advise a great deal of
content consideration before you watch it. Anyway, It's a it's kind of a titan of surreal cinema and an important film when you're looking at weird psychotronic pictures and you know, Mexican cinema certainly cinema of the nineteen seventies.
But it is not for everyone. Yeah, that's not movie Night with the grandparents.
Yeah, I believe the scene in question. It's been a long time since I've seen it, and I have only seen it like used to. The only way you could watch it would be like a rip of a Japanese laser disc. And they're much better sources for it available now. But there is an extended scene where the conquest of Mexico is recreated with like frogs and toads and lizards standing in for the various actors and sides in this conflict.
I did not remember that detail there's a lot I've forgotten about Holy Mountain.
So I would say cameo appearance by the horned lizard. Now, it's worth noting at the top here that we're not dealing with a single species when we're discussing horned lizards, but rather an entire genus of North American lizards, and that's Phinosoma, including some twenty one species which range as far north as parts of Canada and on the southern end range all the way through Mexico and into Guatemala. And of these again, somewhere around twenty one species, at
least eight species squirt blood from the eye region. So just an example of range here, there's the greater short horned lizard or hernandez is short horned lizard, and it can be found as far north as southern Saskatchewan and Alberta and south into the Texas Panhandle in central Mexico. And this is one of the species of bloodshooters.
Yeah, that's right. But as you said, Rob, the various species of horned lizards can be found all over the western part of North America, from down to southern Mexico, all the way up to the southern part of Canada. And you can look up maps that show you sort of different estimated ranges of the different species. But yeah, you'll find them all throughout the arid and semi arid
regions of the North American West. Here, I think it would be a good place to introduce one of my major sources for this episode, which is a book called Introduction to Horned Lizards of North America by Wade C. Sherbrook.
This was published by University of California Press in two thousand and three, and the author, Wade Sherbrooke, was director of the Southwestern Research Station of the American Museum of Natural History, and so one of the questions Sherbrooke addresses in the introduction of this book is why are horned lizards commonly referred to as toads, horned toads, horny toads. Well,
they really do kind of look like toads. They tend to have a wide body when viewed from above, especially in certain defensive postures where they sort of flatten and widen their bodies out to to sort of turn their backs into a shield. They tend to for lizards have a short, blunt snout which can resemble a toad's head,
and they also have an awkward walking gait. They tend to have a camouflaged appearance which helps them blend into their often sandy or gravelly surroundings, and this can resemble the model color patterns and bumpy texture you would see on the backs of some toads, so in lots of different ways they look like toads, and this led to the name of their genus. Frinosoma means toad body phrenos as toad and soma, of course means body, toad body, total toad body to add to the toad comparisons to
make them even more of a toad body. You can observe how they eat. Now. The different species of horned lizards have some different different diets. Some are more taking what they can get than others, but some are quite specialized to eating insects and specifically ants, specifically even more harvester ants. And if you watch the horned lizards eat harvester ants when they specialize in this food source, they have a kind of a sticky flicking tongue action, much
like we associate with toads and frogs. I was reading in one part of the Sherbrook book about how exactly it is that these horned lizards can eat these incredibly venomous ants, and apparently they have a strategy of like flicking them into the mouth and then as they swallow the ant, the ant becomes covered in this layer of mucus that comes out of glands in the lizard's throat, and this coating of mucus surrounds the ant as the ant is digested and essentially disables it from biting or
stinging the lizard from the inside until it is well dead and able to be digested. And these lizards have to eat a lot of these ants because ants are not super nutritious like they've got There's not a lot of meat on that bone. It's mostly bone.
That's right. Like For instance, one of the other big ant eaters out there is of course the mammalian ant eater, and they are known to eat tons of ants and termites, seen estimates of like thirty thousand ants and termites a day. But even that is still a low calorie diet, and it's one of the reasons that we think that ant eaters have one of the lowest mammalian body temperatures. But in terms of the the what we're dealing with here,
the horned lizards consumption of ants. I found an interesting article that answers the question, well, how do they eat them safely? This was from two thousand and eight published in the journal jazz A by Sherbrooke and Schwink. And the answer is in the title Horned lizards incapacitate dangerous ant prey with mucus. And we've already touched on like the main aspect of this, but they provide one more
little detail that I really like. They're write quote. We show that they're derived feeding kind of mattics are associated with unique mucus secreting phar angel papilia that apparently serve to immobilize and incapacitate dangerous ants as they are swallowed by compacting them and binding them in mucus trans And then they later add the detail. Ants extracted from fresh killed horned lizard's stomachs are curled ventrally into balls and bound in mucus.
Take an ant as you as you're swallowing it, coat it with slime, and wadd it up into a ball so that you can digest it without it getting into trouble inside your digestive tract. That's right, roll them up, all right, So that is horned lizards as predators. But I wanted to focus for the majority of today's episode on horned lizards as prey because it is, of course in their role as prey and in their anti predator defense strategies that we see the jets of blood emerge
from the eyes. So here I want to go back to that book I mentioned by Wade Sherbrook. He has an excellent section in this book called the Enemies and Defense, which sort of covers a nearly comprehensive list of different sort of predator prey relationships between horned lizard species and the predators that target them, and the strategies they have for resisting these predators. So, as we alluded to earlier, horned lizards are of course covered in spikes and scales.
This is a pretty sophisticated armor defense. If you've never seen what a horned lizard looks like, by the way, you should look one up. I mean, first of all, they are beautiful, but this will give you a better
idea of what we're talking about. As we continually reference the armor moving on, they tend to have spikes and scales along different parts of their bodies, such as sort of spiky flank protrusions running down the lateral sides of the body, but then also sometimes some kind of bumpy or tough coverings on the back, and then especially bony
spike protrusions around the crown of the head. So some of the spiky looking things, usually the smaller ones, are just more modified scales, but the spikes around the head are actually like hard, sharp bony spikes now covered in spikes and scales as they are. You might not think that a horned lizard would look very appetizing, but you know out here in the arid and semi arid regions of the American West, many predators will take whatever they can get, and so horned lizards are indeed a prey
animal to many species of predators. Juveniles are the most vulnerable to predation. They're smaller and they have less developed armor, so many are eaten between the time they hatch from their eggs and the first hibernation. But Sherbrooke in this chapter gets into a list of different predators, and the first one I want to look at is his section on the long nosed leopard lizard or the Gambelia whizly zennii.
These are worth looking up a picture of as well, because while they're not very interesting in terms of shape, they're just sort of like larger looking predatory lizards. They do have a truly leopard looking coloration pattern.
Yeah yeah, they're quite quite fetching in their own right.
So these lizards will frequently attack and eat horned lizards, especially juveniles, and the general strategy here is not super complicated. It is to bite them near the head and then swallow them whole head first. You know, this is just me reasoning from the pictures, but the sort of backwards pointing orientation of the head spikes, because they sort of extend backward from the head like a crown, it makes it seem like it would probably be easier to swallow
a horned lizard head first rather than tail first. Like if you went backwards, I would think the spikes would would be more likely to catch like hooks in the lining of the throat and the digestive system. But it also seems like eating one of these things head first would be a very no going back scenario. You know, once you start eating a big one, you're committed.
Yeah, yeah, you can't put it in reverse.
Sherbrooke says in the book about defensive strategies that when attacked by a leopard lizard a horned lizard, and again, defensive strategies vary somewhat by species, so we'll be speaking in some generalities here, but the horned lizard will often try to defend itself by flattening out its back into a wide shield shape so it wants to look as wide as possible, and then tilting and orienting its armored shield back toward the predator. And again, Adults with well
developed armor are much less vulnerable to leopard lizards. Now, the next category is birds. A number of different birds prey on horned lizards. Sherbert mentions hawks such as the red shouldered hawk or Boeo lineatus, but also smaller birds like the prairie falcon, the American kestrel, and the loggerhead shrike.
Predatory birds with powerful talons and beaks have an advantage when preying on these lizards because they have the ability to tear the lizard apart and eat it piece by piece, making it a somewhat easier proposition to consume that this spiky animal as opposed to an armored adult that needs to be swallowed whole. However, it does still come with risks. Sherbrooke mentions one case of a red shouldered hawk that was found dead after having eaten a couple of Texas
horned lizards. Apparently one of the horns had pierced through the hawk's throat from the inside. Oh, and I can't help but apply like a human level of grossed out to this. Like I know it's just part of their, you know, their way of making a living, But I cannot imagine eating something this spiky.
And it's like a like a like a wheat then, except even worse.
Right, Yeah, Oh, it's like you know, you ever think when you're like eating a tortilla chip and you don't chew it upright and you get a shard caught in your throat. Yep, okay. Another bird that preys on these animals is the greater road runner or Geocossics californian us.
The greater roadrunner has an interesting strategy where it grabs the horned lizard by a leg or by the tail with its beak, and then it whips them up in the air and slams them back down against the ground repeatedly, so it is beating the lizard against the earth, using centrifugal force to smash it dead. Basically, it bashes it and bashes it until it is dead and busted up, and this allows the roadrunner to take its time orienting the lizard so it can be swallowed whole head first.
Rabbie attached to a picture for you of the Greater Roadrunner trying to get this whole lizard into its mouth head first that I don't know how this is going to happen. This is just a photo from the book. It's not animated, but I believe in you.
Yeah, yeah, yeah, I mean, roadrunners are such interesting, weird creatures in their own ride. I don't feel like the cartoons properly prepared as for the reality only seen. I've only seen them in the wild, I think one or two times while out in the Arizona. But it's like it's like seeing like the ghost of a dinosaur run by. It's pretty neat.
Yeah yeah yeah. And of course, in the case of the roadrunner swallowing it headfirst once again, keeps the horns pointed away from the bird's vital organs. It's going down the digestive tract.
Clever girl.
Yeah yeah, okay. So another bird predator, Chihuahuan ravens or corvas crypto. Lucus Sherbrook says that these birds, they've got an interesting difference here. They bring dead horned lizards to their nests to feed their young, but the ravens render them safe by not feeding them to their young hole, but instead ripping them open and only feeding the soft innerds to the hatchlings, so only guts for the children, and then the carcass with the hard parts is discarded.
All right, Well that's not surprising. I'll leave it to the ravens to intelligently dissect before eating. To the end.
They're like a tourist at a beach restaurant picking the meat out of a crab. They're getting all the juicy bits and not swallowing the hard parts. Of course, snakes are a major predator of these lizards. Various species of snakes prey on them, killing them either with venom or with constriction, and then in all cases, swallowing them whole. Snakes, like birds, do incur some risk by attempting to swallow
a horned lizard. Sometimes the horns rip them open from the inside, and a crucial factor seems to be just the relative sizes of the snake in the lizard. The snake it's hungry, but it can't get too greedy. It has to know its limits. And so I guess there are cases where a snake might be sort of driven near starvation and it's pushing the boundaries of like, is this thing so big it's gonna kill me to eat it?
I'm gonna roll the dice. Now, that's not all the potential predators of horned lizards, but I'm gonna come back to one more major category in a minute when we get to the blood squirting. So there's another interesting framework that Sherbrook introduces in this chapter where he's talking about the different levels of defense that a prey animal can
deploy when trying to survive against predators. And the three layers of defense he talks about are first of all, avoid being seen, second, avoid being caught, and third be difficult to eat or appear dangerous to the predator. And you could sort of paraphrase these as one hide, two, run in three fight. Horned lizards are not very good at number two. They're not very good at running away. There are some exceptions, such as when facing off against
certain snakes venomous snakes like the diamondback rattle snake. Sometimes in facing off against one of those, the lizard will just run away, But in most cases it's not going to be great at trying to outrun predators, and they've got kind of short limbs and awkward movements. So mostly horned lizards excel at number one and number three avoiding
being seen in the first place. And then if they really if they're cornered and they're caught and they can't hide anymore, they resist being eaten somehow by a combination of morphological and behavioral defenses. So we'll look at number
one first, the hiding part. Horned lizards are masters of camouflage, and Sherbrooke has an interesting side note about how we often don't appreciate how effective a wild animal's camouflage actually is because most people, you know, if you're not like living out in the wilderness, most of the time you're going to see any of these wild animals, it's in some form of media that is designed to help you see the animals, such as like a picture in a book or foot in a documentary where the whole point
is that you're supposed to be able to see it, And so this kind of we kind of underappreciate how effective natural camouflage strategies are because if we were just walking around in the environment, we likely might go right by animals of this type and never see them, so we wouldn't even know that we'd miss them.
That's a great point.
Yeah, And so horned lizards are very good at hiding. They hide themselves with a couple of strategies. They hide by disrupting predator search routines for both shape and color, so their coloration tends to mimic the patterns of gravelly, sandy or grassy grounds where they live, and the pigment in their skin tends to match the color of the local soil or whatever the background is. So, for example, horned lizards that live in areas with redder soil will
be redder in color and so forth. Also in the domain of color, they have patterns of what is called disruptive color. This is found in many animals where varied color patterns make it harder to pick out the outline of an object against the background. This is also one
of the main principles behind human tactical camouflage. Some of their hiding strategies are more obvious, like in some cases, if there is a predator around, they might increase their hiddenness by ducking underneath something so they can run under a shrub or a rock or some of their groundcover. But another thing they do often is if a predator is nearby, they can flatten their bodies against the ground.
And this especially helps protect against, say, the visual detection by birds, because this flattening prevents them from casting a shadow, which if they did cast a shadow, would reveal their outline. So if you can't see the outline of the creature, it disrupts the predator's shape recognition. And the horned lizard's lateral body spikes also help disrupt shape recognition by interfering
with the casting of a shadow. Now, in order for a lot of these hiding strategies to be effective, the horned lizard needs to remain motionless, which it does much of the time. It pays to be sedentary if you're one of these buddies, and it also helps that you know as ectotherms, they need to spend a lot of time absorbing sun anyway. Because their body temperature is dependent on the surrounding environment, they don't generate their own body
heat through metabolism. Now, one defensive strategy that Sherbrook talks about, which in a kind of embarrassing way ping done some like video game playing styles I'm familiar with, is that if startled, the horned lizard will often run as fast as it can a short distance and then suddenly stop and freeze. Why would it do that? That doesn't seem to make a lot of sense, but it does actually
if you read it explained. So the lizard usually can't run very fast, very far, but the main purpose of it seems to be too quickly re enter stealth mode, so you run a short distance and then freeze in order to once again blend into the surroundings and hopefully
disappear from the predator's vision. This makes me think of various I don't know, like Batman video games and stuff where the bad guys see you and this like oh oh, I need to run to the opposite side of the room and hide, and then they'll all be like where'd he go?
Or like a metal gear game where you just immediately put a box over your body and then they're looking right at you and maybe they won't see it.
Huh.
But you know, I have to say I only have human eyes. I don't have the eyes of an eagle, and they're not even great human eyes. But you know, there have been times where I've been watching an animal in the wild that is really good at its camouflage, and you know, either it will be the situation of looking right at it and not seeing it until there is movement, or the reverse kind of looking at it in movement and then the second it stops, I cannot see it anymore. I know it is there, but I
cannot actually see it. It's just based on the memory of what just happened.
So yeah, that's how it works for predators also. I mean it's again we underappreciate how effective camouflage can be because we're so trained on this, like media that shows you this is where it is, look right here. But okay, let's say all of that has failed. Your invisibility camouflage stealth mode has failed. You're a horned lizard and you're
cornered by a predator that definitely knows you're here. Here, we get to the active defense strategies where you try to make yourself look difficult to eat or dangerous to the predator. Now, the range of behaviors described in Sherbrook's book here are surprisingly diverse. I wouldn't have expected this many different things to be on the record, but Sherbrook lists a number of them, just in respond to the
presence of humans. To read from a paragraph here quote in an almost comic antic one horned lizard raised itself high on all four legs, lowered its head, and in a series of hops, approached its tormentor like a charging bull. On another occasion, a horned lizard charged and bit a person's boot. Normally they do not bite when captured by hand, but some struggle an attempt to thrust their horns into the flesh of their captor. Now that's kind of interesting, though.
There are also reports that a good number of these lizards, if picked up and handled and sometimes rubbed or stroked, they will become immobile. And this could be some kind of death feigning strategy as seen in some prey animals. You might wonder, like, why would it be advantageous for a prey animal to pretend to be dead when it
has been gripped by a predator. There could be different explanations, but I think it's generally understood that if you pretend to be dead, you can wait for the predator to relax its grip focus in order to have a moment to escape other defensive behaviors. When cornered, sometimes a horned lizard will inflate its body, going to puffer fish mode. This will certainly make it look harder to swallow, and
maybe actually be harder to swallow. Remember, predators can die from eating a horned lizard that is too big, so you want the predator to be wondering if you are over.
The line look more difficult to eat.
Another strategy is the backshield thing I talked about earlier. So you can sometimes flatten your back into a round shield and then tilt and orient your back towards the predator. This makes you look big, but also makes you look difficult to eat. But apparently in other cases they'll do the opposite. They'll quickly just turn and face a predator head on. Sometimes they hiss like a snake. This could be a signal to convey danger and aggression. Sometimes they'll
kind of vibrate their tails. Now there's some other predator defense strategy stuff that we might come back to in part two. But I want to get to the blood squirting here because this is the main event for me. Sometimes when a horned lizard is threatened, it will blast a jet of its own blood out of its eyes toward the attacker. Now, again, Rob, I think you mentioned this earlier. Not all horned lizard species have been observed
to do this. At the time of Sherbrook's book, he did say that most species were known to be blood squirters, the majority, where I think maybe there might be more different species identified now, so it might not be the majority at this point.
I believe that's the case, but we can look again at that data before we come back with part two and clarify if we need to.
Okay, well, certainly some species do this, now, they don't do it every time they're threatened. It seems like a fairly specialized behavior. Sherbrook says that among two species, Texas horned lizards and regal horned lizards, blood jetting happened during four to six percent of human captures. So that's not most of the time. You know, it's like one in twenty times. It sounds nuts. So it was indeed sometimes
believed to be a myth, but it is real. So Sherbroch writes that, you know, if a lizard is about to squirt blood out of its eyes, you're going to see this. In preparation, the lizard arches its back and it closes its eyes, and the lids around the eyes become visibly swollen, like you can see that something is building up there. And then suddenly a thin stream of blood jets out of one or both eyes, and it
can be shot in either direction, forwards or backwards. This blood spray can reach a distance of about six feet, and the jet lasts for about one second per blast, though the lizard can usually do it again if the threat persists, so it's not just like one and done. You can blast more than once six feet.
That is crazy considering the size of these creatures.
They're a little things, aren't they. Yeah. So does the lizard lose a lot of blood from this? Yeah? Yeah, yeah, it does, but it usually recovers if it escapes the situation, so it's not like a lethal amount of blood loss, but it it does lose a serious amount.
Better than losing all the blood and the body as well.
That's right, so research has shown that the horned lizards are able to do this via a mechanism that rapidly increases blood pressure in chambers within the head. So the way it works is that blood flows into the head via the arteries, but then the lizards have a set of muscles that they can use to squeeze closed the veins, leading blood back out of the head. So when they squeeze these muscles, blood flows into the head but not out, and excess build up of blood flows into the ocular sinuses.
These are voids within the facial tissue around the eye socket, and this manifest tests externally as bulging eyelids. Eventually, the pressure becomes so great that the capillaries in these sinuses burst. Blood is rapidly released and escapes through the easiest route to the surface, through the eye and the tear duct, and here you get the blood jets. Now there's a sentence in Sherbrook's book that I love. There's like, oh, there's such a story behind this, and no description of
what this means. Sherbroke writes, quote, humans sampling the blood sprayed do not taste anything strongly objectionable.
That statement raises a number of questions, who methodology past history with the sampling of lizard blood? Yeah, and I mean one of the key questions though that arises from this, is of course that in a lot of the literature the reason cited for the blood spurning is that there is something objectionable about the taste or sensation of this creature's blood.
Well, I think there is, but maybe not perceptible to humans. So what is the point of the blood squirting? Well, according to Sherbrook, a clue comes down to the relatively selective employment of this defensive behavior against only certain predators we mentioned it only happens in like four to six percent of human captures. The lizard usually does not squirt blood out of its eyes at other predators we've mentioned earlier, like birds, leopard lizards, snakes. So who do they use
it against? Dogs? Wild cannids such as the coyote and the kit fox or Vulpius Macrotis any type of dog attacks a horned lizard, Here come the blood jets. When any of the sprayed blood gets into a dog's mouth. Sherbrooke says that you can usually see the dog showing obvious displeasure with the taste, like shaking its head back and forth, sometimes chewing or wiping its mouth on grass, as if trying to get the taste out of its mouth.
Oh wow, no, this yeah, this makes a lot of sense then. I mean, we've talked before about how dogs their sense of smell and therefore their sense of taste is just in a realm, so far beyond human levels of taste and scent that it's just a different, a different universe.
Sherbroke writes, quote, clearly there is some chemical component of the blood that causes dog family members goosetatory or taste distress. The blood never harms them, but it certainly suggests to them that a different meal would be more palatable. How fortunate for the horned lizard to be able to deliver
that message before being severely bitten and tasted. And Sherberke notes that there are some other lizards, not horned lizards, that have occasionally been seen bleeding lightly from the eyes under stress, and he speculates that perhaps something like this was an early stage in the evolution of this more elaborate defensive measure, maybe slight bleeding from the eyes under stress, and then horned lizard ancestors have blood that is for
some reason distasteful to canids. Sometimes that gross blood makes a predation attempt stop, and then there's evolutionary incentive to bleed more and more of it preemptively to make the predation attempt stop earlier and earlier before major injury has occurred, until you end up with six foot jets of eyeblood.
It's like really aggressive free samples in the mall food court. Yes, but instead of trying to bring certain customers in, you're trying to convince them this food is not for you. Here, have a taste.
But so why is this blood apparently distasteful to canids to dogs?
So it seems like the main hypothesis, based on what I was looking at, is that it comes down to what these creatures eat. What the horned lizards eat, they eat copious amounts of ants, and those ants contain formic acid. So apparently previously researchers thought that the acidity was more of a glandular product, but now we understand that it's the blood, Like that's what's shooting out. There's nothing being
added to the blood. The blood in and of itself is supposed to have this formic acid quality.
That's right. Sherbrooke makes this point in the book that it was once thought that maybe there were glands around the eyes adding something to the blood before it gets blasted out, but they said no, there's no evidence of that.
Interesting side note, I've already mentioned another big time ant consumer, the giant anteater of Central and South America. That is a creature that cannot produce its own stomach acid apparently, and instead depends on formic acid from its prey.
Wow.
Yeah, I didn't know that. Another interesting fact concerning horned lizards here, they apparently don't eat fire ants. Fire Ants are, of course invasive ants from South America beyond the southern limits of the horned lizard's range. They often they're really more of a threat to horned lizards because they can push out native ant species that the horned lizard depends on, while also provoking human inhabitants to deploy anti ant measures
that you know, just don't discriminate. So all of this plays a role in the habitat loss and decline of various horned lizard species.
Yeah, I'd read that as well. Many horned lizard populations throughout the throughout North America have been in decline in recent decades, and yeah, fire ants are implicated as part of the picture for why that's happening.
A related question that I didn't even think to ask what I just saw come up when I was searching around for answers on this, people ask, well, can't we get some ant eaters and some armadillos in on these fire ants, as these creatures do eat fire ants. And the answer there is no, not really, because like an ant eater eats a lot of ants, but it has to go in like in quick bursts, because it's not immune to the bites, and so it's got to get in, like, you know, eat a bunch of ants and get out
of there before it gets too painful. And they're not going to finish off a colony, like they're not going to eat it down to the queen, you know, they're not going to eat it down to the last ant. It's like a devastating raid. But then they have to move on, so it's not going to like wipe out populations necessarily. M But yes, it seems like the consumption of ants is key, and I think we're gonna go ahead and close out this episode, but we're gonna be
back on Thursday. We're gonna get into various other angles concerning the horned lizard and also some of the traditions surrounding it, including again I teased out some Navajo traditions, and there there is one story we're going to come back to about the Holy Toad who eats ants that give him power. Whoa which is correct? The research they're looking at here absolutely correct.
I can't wait.
All right, Well, we're going to go and close it out, but in the meantime, go ahead and write in with your observations concerning the horned lizard. You've seen them out in the wild, you've studied them, write in. We'd love to hear from you. We'll come back with part two on Thursday. A reminder that that's when our core episodes published Tuesdays and Thursdays every week and the Stuff to Blow Your Mind podcast feed, where we are primarily a
science and culture podcast. We do a short form episode on Wednesdays, and on Fridays we do Weird House Cinema. That's when we set aside most of our serious concerns to just talk about a weird film.
Huge thanks to our excellent audio producer jj Posway. If you would like to get in touch with us with feedback on this episode or any other, to suggest topic for the future, or just to say hello, you can email us at contact stuff to Blow your Mind dot com.
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