Listener Q's: Third Eyes & Swole Gorillas

I'm your host so many parasites, Katie Golden. I studied psychology and evolutionary biology, and today on the show, it's another listener Questions episode. I answer your questions to the best of my ability. You can write to me at creaturefeuturepod at gmail dot com with any questions you have about animals evolutionary biology. Can send me pictures of your pets, and I love to answer these questions. They often send me on very interesting sort of study sessions trying to

find out about your questions. And let's just get right into it. First listener question, Folks say things like crocodiles have been around for x million years, relatively unchanged, and obviously evolution is an ongoing process. But speaking to classifying animals, what's the oldest and what's the newest animal? When and how do new classifications of species happens. This is from Blake our Hi Blake. This is a really interesting question,

very good question. It is a bit of a touchy topic in evolutionary biology because the broad answer is that definition of species and distinctions between species can be a bit of a gray area. So there are different schools of thought when it comes to defining species. One is the biological species cheese concept. It defines a species as

a group that can produce viable fertile offspring. So while a horse can technically have offspring with a zebra making a zores, the resulting hybrid is infertile, so the horse and the cibra are considered separate species. But this concept has some issues. It's not something that can easily be applied to fossil species, so we may not know whether they can produce viable fertile offspring or not. It also

doesn't take into account speciation by geographical barrier. So perhaps two species that got separated are and are on different continents could reproduce viable fertile hybrid offspring. But does it really mean that these species that have been living apart for millions of years are the same species. There are also species of animals that reproduce asexually, and so the

biological species concept doesn't really apply to them typically. I mean, usually when you have asexuality and species, they do go through phases of sexual reproduction, but still it adds a layer of complexity. There are also species that are quite clearly anatomically distinct, such as polar bears and grizzly bears, who can freely hybridize and produce viable, fertile hybrids. So pizleies and grollar bears are actually fertile and they can

have offspring. Neanderthals and humans are considered different species. I mean we have different evolutionary lineages or more cousins than We didn't evolve from Neanderthals. We are cousins to Neanderthals, but we still have a lot of Neanderthal DNA floating around in our current human populations because of how we

interbred successfully with the Neanderthals. In fact, one of the theories of Neanderthals disappearing is that, sure, we probably killed a lot of them off or out competed them, but a lot just simply kind of like integrated into human society, like we have Neanderthal DNA. There was a lot of interbreeding and so yeah, it just kind of Neanderthals became

subsumed by humans. So basically defining what a new species is can get kind of messy, and there are some rough ways to do it, such as seeing if they can interbreed, looking at geographical location, looking at phenotypical differences so that's like what they look like, what is on the outside, and even examining genetic lineages and differences. So generally, if you have a species evolving into another species, it will either be anatomically, locationally or genetically distinct enough that

scientists think it deserves its own category. In terms of Blake's question about oldest in newest species, things like sponges and comb jellies are probably the oldest animal species. These are oceanic species like sea sponges comb jellies that are these very simple looking interesting like almost transparent orbs or like tiny blimps. These probably came about over seven hundred

million years ago. For comparison, crocodiles are only two hundred million years old, and the first flowering plant popped up only around one hundred and thirty million years ago. In terms of the newest animal. That's a little bit trickier given that evolution is a fluid process. It's happening all around us, and we simply don't have researchers looking at every single animal species on the planet being able to

detect exactly when speciation happens. But an example of one of the newer species on Earth is a finch on the Galapagos Islands. Those same finches that Darwin noted had differently shaped beaks for the different types of seeds and food found on the different islands are still going through evolution. So in the nineteen nineties and early two thousands, researchers noted that a cactus finch had migrated over to a Galapagos island that it's not native to, the Daphne Major Island.

Then researchers noticed a hybrid species come from this invader cactus finch and a native medium ground finch. The new hybrid species is actually fertile and has to breed only with other hybrids because they have such a different beak shape and different song to track females, it can really only breed with other hybrids, so of course there's a lot of inbreeding, but they managed to continue to function and grow to be a population of around twenty three

into vials and eight bonded pairs. So I think researchers considered this a new species. So this just happened basically in the early two thousands, so that's pretty recent. I mean, this is by no means does this mean this is the absolute newest species. We just this is a relatively recent one that where we sort of notice the speciation. But yeah, this is probably happening too many species over the around the Earth, but we just simply don't know.

And you can like track sort of the genetic changes and be able to see like when these kinds of speciations have occurred. But yeah, it can be quite recently, just within the last couple of decades. So we're going to take a quick break and then answer more listener questions. Here is another listener question. I thought maybe one idea for an episode could be unusual ways animals evolved to be aware of enemy or prey in their environment or

have you done something like this already? I mean heads that spin around, weird eye placements for three hundred and sixty degree views supernatural senses only sleeping with half of your brain at a time, you probably know better ones. So this is from pekin In who sent me a really cute video of a kingfisher who has really amazing rotation of the head so it can turn its head much like an owl and look all scan all around

rather than moving its eyes. I may indeed use this idea for a full episode, but in the meantime this suggestion actually made me think of weird eyes. And one of the weirdest eyes I can think of is this third eye that a lot of animals have called the parietal eye. So this is present in amphibians, lizards, salamanders, to ataras, which is a lizard like reptile. It's also found in lampreeze, which are these sort of eel like fish. They're found in some species of fish and in sharks.

So the third eye is not like a wide open, regular eyeball, but you can often see a small bump or ridge on top of the animal's head, or in species that have interesting coloration, sometimes you see like a band of coloration around the eye. So it usually presents as this tiny gray oval and As the animal matures, it usually gets covered in a layer of skin. So

the eye is not like the other two eyes. It does not have the rod and cone photoreceptors that we have in say, like our eyeballs, but it is more like a photosensitive mass that is connected to the pineal gland. So the pineal gland has roles in hormone production and regulating circadian rhythm and thermal regulation. So it's thought that this parietal eye also helps in these processes. So one theory is that it acts as a docimitter, which is

a device that measures ionizing radiation. So the idea is that this is basically a biological docimter. So the parietal eye could potentially help regulate hormone production and thermal regulation based on the intensity of the sun's radiation. So which you know, seems to make sense, like you need to know like how to regulate your body's temperature if it's hotter outside, or how to regulate say, melatonin production based on the sun's position in the sky in terms of

regulating sleep wake cycles. So when researchers remove the third eye, this parietal eye, from lizards, it seems to mess up their basking behavior and activity schedule, which shows it basically functions like a sun's sensitive watch for lizards, helping them know when they should be most active, when they should rest, and when they should either bask in the sun or or find refuge in the shade. It also seems to help lizards with navigation, using the sun as a marker

and knowing how to navigate by memory. So in an experiment, lizards were trained that there's an invisible ledge in this pool of water, and they were basically they learned how to use the sun to navigate to this ledge, but when their parietal eyes were either covered or just surgically removed, they would swim in these random directions and fail to

be able to find this ledge. It seems like it's also functioning as an internal compass by using the radiation as a sun as sort of a marker, and then being able to track like the lizard's relative position to the sun to determine location, which is really cool. I wish I had a third eye. I'm really bad at navigation. I very easily get turned around, so I could use all the help I can get and it would look really cool. We're going to take a quick break and

answer another listener question when we get back. Next listener question, I have a question for your Listener Questions podcast. Why are gorillas so big and strong? Animals usually only invest that much energy into muscle if there's some evolutionary advantage, But what do gorillas get out of being so strong, especially compared to other primates? Thanks Gary, Hi, Gary, So this is a really interesting question because gorillas are herbivores.

I mean, sometimes they will eat termites and ants, but either way, these food sources don't necessarily require a lot of strength to eat. In fact, there are many herbivores that are quite strong, like hippos. So it's very interesting when you see, like, you know, actually carnivores certainly do not have the monopoly on being strong, and some of the strongest animals are herbivore and they get all of their sort of muscle mass from vegetation, which is really interesting.

So gorillas, unlike certain species like hippos, are actually not that aggressive. They don't typically use their body mass to just like you know, mow down other species. They're one of the more gentle primate species, especially with conspecifics. So conspecifics means a member of your own species, and gorillas tend to try to avoid conflict with each other, but the males will get territorial. They have a harem system where there is a dominant silverback gorilla who controls a

troop of gorillas. Usually it ranges too up to like thirty individuals, including females and juveniles and babies, and the dominant male has the exclusive mating rites with the females unless being sneaky, and so he will attack any other males who tries to basically take over his territory, which comes with those mating rights to those females, And often there will be these aggressive displays, you know, chest thudding

that that kind of like trope is. It's true. They will try to seem like like, look I am big, I am scary and strong. You don't want to take me on as a challenger, so that they you know, they would prefer to settle things relatively peacefully so they don't have to risk being injured. But they will fight, and sometimes they will fight to the death, especially when you have two troops of gorilla coming together. You have two dominant silver backs and they are trying to fight

over territory. They can sometimes kill each other. They are also highly defensive of their families, both females and males, and they will definitely turn you into a body part salad if you come off as a threat to them or their family. But when you compare them to something like chimpanzees, they are a little bit less aggressive. Chimpanzees are a bit more I guess, ornery of a species. So why they're so strong, I mean, one thing you

look at is the difference between males and females. So for the Western Lowland gorilla, which is found in the Congo basin, males weigh around three hundred to five hundred pounds, which is around one thirty to two hundred thirty kilograms, whereas females range from about one hundred and fifty to two hundred pounds, which is about one hundred and fourteen kilograms. So females are quite a bit smaller than the males, and this is a hint for what the strength is

typically used for. The relatively greater strength of the males is likely a great benefit to them so that they can defend territory and access to females. So evolutionary pressures would greatly reward these stronger, bigger males, and with enough access to vegetation to feed their bulk, they are able to get very large. Now, unlike humans who have to like work out, go to the gym, do reps get swollen to maintain muscle mass, Girls' metabolism will automatically convert

vegetation and cellulose into muscle mass. And they spend a lot of time on the ground rather than in the trees, so they're walking on their arms and a lot of like upper body strength used to move around, and they kind of have traded off the nimbleness of say like a chimpanzee who can spend more time in the trees

for just being more of a tank. So the large silver backed dominant males can lead these troops around, you know, thirty individuals, like I said, and you know, even when he is threatened, he tries to kind of just put on this display. So they really are more docile then

a lot of species. That doesn't mean you should try to approach one and like give him a fist bump or something, because he will ruin your entire body if he thinks you are a threat, like and you know you're a strange a stranger basically coming up to his family. He's not gonna assume you're there for good purposes. Another thing that they can use their strength for is to rip in tear branches to get up vegetation. And young gorillas will easily scale trees, but the adults really don't

spend too much time in the trees. They can climb trees, though, and they will if they want to get a snack up there. So in terms of the question why why gorillas are so big compared to chimpanzees, I mean, one thing is that you kind of have this this thing that happens in evolution where it doesn't you don't always have to arrive to the same evolutionary design in order to be a successful species. So it's whatever evolutionary path

that takes you towards something. So you have probably the selection for larger males because that makes it easier for them to compete for females in their environment. And then you have this kind of run a voye selection where like they get bigger and bigger, and as the males get bigger, the females also have to get bigger. I mean, you can't really have like a Chihuahua sized female and a you know, like girlicized male, So the females also will get larger in size even if there is this

sexual dimorphism. Availability of vegetation is important, so if they live in a habitat where they really do have a lot of access to the food they need to nourish their bodies, that will allow for a larger size. Oh, an extinct primate called Gigantopithecus is it's like it looks like this, like huge a tan. It went extinct because of climate change, and they were so specialized in eating

very specific vegetation. Once that was reduced by the change in climate, they were not able to generalize their eating behavior enough and they would they just died out due to lack of nutrition to maintain such a huge body. So being big is great, but it comes with this trade off, right, Like it means that if there are fewer resources, you are in a lot of trouble. So that's that's why, like not all species just like go towards being as big as possible. There are other ways.

There are other ways to be successful as an animal. So while you might think that gorillas face no threats other than humans, given how giant they are, they're young, are actually quite vulnerable. So there was this case when seven gorillas were attacked by twenty seven chimpanzees for over an hour, during which time the chimpanzees were able to separate one of the babies from its mother, They kidnapped it,

they killed it, and ate it. Nature is really brutal sometimes so, but you can see that even with all their strength, gorillas can be victims of attacks by huge mobs of chimpanzee. So the fact that they're really physically strong doesn't necessarily always give them an advantage to protect their young against chimpanzees who are able to just kind of a mass an army and be quick and nimble

and then like steal away some of their young. So that large size does come with some downsides, which is agility, being able to quickly you know, hide, and so you know, I think that you and also what I mentioned earlier in terms of like getting enough vegetation, it might increase competition because each individual needs more food. So it's a trade off and it's not going to be the path at Some species take getting that big, but yeah, some

species like it. It has worked out for the grills pretty much until you know, humans came into the picture and we've really been messing with them in terms of their habitat, and that's the main threat to them. Chimpanzees are not like the biggest threat. It's it's humans as usual. We are the most dangerous primate. So onto the Mystery animal sound game. Every week I play a mystery animal sound and you try to guess who is making that sound.

So last week I actually did a rerun episode. I've been actually visiting the US, so I live abroad, but I came back to the US to visit family, visit friends, go to a few weddings. So last week I played a rerun. I might do the same next week. We'll see. I'll try to fit in another recording, but if I can't, I will pick out one of my favorite episodes for

you to listen to. First, let us go over what was in the rerun episode, because there was a mystery animal sound and the hint given was this Its name sounds like a collaboration between a biologist, a heavy metal band, and a hairdresser. So congratulations to Amanda and Boyd and middle school grade seven for guessing correctly. The screaming Harry armadillo. So the screaming Harry armadillo is exactly as it sounds. It's a very hairy armadillo and it screams when it

is handled. So they are found in Central and South American desert environments and they do not like to be picked up. And when a human picks them up, usually in a zoo or wildlife rescue organization, they will make this horrible man drake shriek. So onto the next mystery animal sound from the episode missing parts from two weeks ago. The hint this hairy animal doesn't want his picnic on a rainy day. So congratulations to Auntie Bee, Emily M and David D and David D's son Xavier, who all

geessed correctly. The sun bear. So. Sun bears are the smallest bear species, weighing only around fifty to one hundred and forty pounds around twenty five to sixty five kilogrounds. They are found in rainforests in Southeast Asia. They have a patch of yellowish fur on their chests and are otherwise black with these tan muscles. They are very cute.

They're pigeon toed with feet facing inwards and have large hooklike claws, allowing them to easily climb trees to get both protection and food sources such as honey bee's fruit. They'll rip open hollow trees just to get at the bees and honey inside. They eat also vegetation, termites, even small vertebrates when the chance arises, basically anything tasty that they can get their cute little Freddy Krueger claws on. In addition to threats from humans, young sunbears must contend

with predation by pythons and leopards. Otherwise, they live in pretty hospitable environments, and they have enough nutrition to be active year round, and they do not hybridate onto This week's mister animal sound, the hint squeakers here doesn't like being handled. In fact, his own hands have turned into something very different through evolution. So do not adjust your podcast. That is an animal noise and not just the audio

going crazy. Uh if you think you know who is squawking, each right to me at Creature Futurepod at gmail dot com. All right to me with your questions. I do these listener questions episode relatively regularly, so I try to get to every question in my inbox. And if I don't answer it on the show. I do try to respond to those emails, even if I am slow like a sloth. I will get there eventually. So thank you guys so much for writing into me. And thank you to the

Space Classics for their super awesome song XO. Lumina Creature features a production of iHeartRadio. For more podcasts like the one you just heard, visit the iHeartRadio app, Apple Podcasts, or Hi Guess what. Maybe I listen to your favorite shows. Look, I will not rat you out to the podcast police. Don't worry. See you next Wednesday.