Listener Q's: Shrinking Ant Brains

species are parasites. How have parasites become so successful? And what role do they play in healthy ecosystems? Thanks Michael D. From Sacramento. Hey Michael, thank you for your question. So first I wanted to check on this whether it is true that half of all animals are parasites, and it seems roughly accurate. I've seen about forty percent being a number kind of bandied about, but I think it's a

little bit tricky to get an exact proportion. One thing is that number of species is somewhat subjective, like do you count subspecies? How closely related are the different parasite species and so on, And of course biomass would be quite difficult to calculate as well, but I think the point still stands. There are a ton of parasites out there,

perhaps more than we would be comfortable acknowledging. So to understand why there are so many different species of parasites, I think we should go over all the different kinds of parasites that are out there, because not all parasites follow the flea sucking blood type model for parasitism. So the flea type like the flea sucking your blood, is

an example of an ectoparasite. Ectoparasites live on the external body of their host, and they feed on their host's blood, skin, or other important bodily components in a way that is detrimental to the host. And endoparasite is similar, but it lives inside the host. So an example would be a tapeworm. It feeds on the blood supply, flesh fluids, things that are inside the host's body which the host needs. Remember,

parasites are necessarily by definition harmful to their hosts. It is a form of symbiosis in which the parasite harms the host in order to benefit itself. So another type of parasite are the parasitoids. So parasitoids live on or in their host. But the difference between a parasitoid and another parasite is that parasitoids end up necessarily killing their host.

So an example is basically any number of species of parasitoid wasp who will lay her eggs on a host, and those eggs hatch either on or inside of the host, and the larva will eat the host until it is dead. Like the parasitoid wasp that attacks orb weaver spiders, these larva will live on the orb weaver, slowly drinking their fluids until the orb weaver is dead. So a parasite that accidentally kills their host does not count as a parasitoid. So say you have a really bad tapeworm, you get

really sick, and you die. The tapeworm is not a parasitoid. It's just a parasite. It's not obligatory for the tapeworm to kill you, but parasitoids necessarily consume their host. Parasitoids can be ectoparasites, endo parasites, or in some cases, the host can be paralyzed, dragged back to a din, and slowly eaten over the course of hours, days, or even months. In fact, some parasitoids will specifically target non essential organs

first so that the host species lives longer. This gives them more opportunity to eat flesh that is not rotting, that is fresh, So parasitoids blur the line between the categories of predation and parasitism. Also blurring lines are micropredators such as mosquitoes or vampire bats. They are parasites, but they don't don't live on their host or on a single host. Instead, they go from host to host and will take little SIPs of their blood or feed on

whatever it is that they feed on. But they are not quite predators because they do not directly kill or consume their host. They can incidentally kill their host through spreading of pathogens, but this is not the same as you know as by definition killing their prey, So they are micro predators. They are parasites. They don't kill their host,

but they can accidentally kill their hosts through pathogens. And actually, speaking of spreading pathogens, this is related to another way to categorize parasites in terms of the way that transmission works. So vector transmitted parasites use a taxi in order to infect their host. So think of a protozoan parasite that lives inside a mosquito. That mosquito goes to its target, maybe a human, maybe an animal, and plunges its proboscis into your skin, and then that protozoan can go on

to infect you. So the protozoan is a vector transmitted parasite. It is using the mosquito as a taxi and it enters the host via this little living taxi, and it causes us all sorts of problems like malaria. So very important thing to know about these vector transmitted parasites if you are, say a doctor or epidemiologist. So directly transmitted parasites go by foot or wing flagella, wind, et cetera.

They directly trans port themselves to their host. So an example would be a flea jumping onto your dog, or you picking up a tick while walking through grass. Another type is trophically transmitted parasites. These are parasites that want to be eaten. They are eaten by their host, or, as is often the case, they are eaten by one species and then a subsequent species, which is their true target, and then they reproduce and feed inside of their final target.

An example of this includes roundworms. Another example is te gandhii, everyone's favorite rat Zombi Fie protozoan. It will infest rats. It will cause lesions in their brains, which makes the rats uncharacteristically bold an affectionate towards felines, who return the love by eating the rat and the protozoan. This Tea gandhii will happily reproduce inside the cat, who then poops

out more Tea Gandhi. The poop gets around the rat accidentally in just some of that poop particle, and then it gets the Tea gandii and the cycle begins again. This is a trophically transmitted parasite. There are other types of parasites that are sometimes forgotten different categories, such as kleptoparasites. These are parasites that steal food from other animals. So seagulls who love to snatch food out of another bird's

beak are kleptoparasites. Brood parasites are parasites that will use the paternal or maternal care of another species in order to benefit their own offspring, so cuckoo birds laying their eggs and tricking other birds into raising their chicks is an example of a brood parasite. Now, a very tiny but interesting category is sex actual parasitism. It describes only what anglerfish do. This only applies to anglerfish specifically. It is where the male attaches itself to the female physically

graphs itself to the female. It actually uses an enzyme that kind of melts the skin of the female a little bit, so it can kind of melt itself onto the female's flesh. Then it feeds off of her blood supply, and the only thing it doesn't return is produce sperm. So the argument for this as a case of parasitism versus say, mutualism, is that the male takes more than he provides, so like if he's taking more of their female resources than he provides in terms of say, sperm donation.

Social parasites are another category parasites. These are parasites that infiltrate usocial or other types of social groups of animals, mimicking them or sneaking by a notice, stealing resources from the group, tricking adults into feeding them, or feeding on

their young. So there's a type of blue butterfly species where the caterpillar mimics the larva of ants, the ants will take it in, and sometimes it actually can imitate the queen signals of the ants, further tricking the ant colony, and it can go around feeding on larva or allowing itself to be fed by the ants. So it's a really sneaky form of parasitism. Another category is hyper parasitism.

So hyperparasitism is basically the old rhyme. Big fleas have little fleas upon their backs to bite them, and little fleas have lesser fleas, and so on at infinitum. So I actually had another listener question about how many levels of parasites you could have. This is from Jean Luke Picorgi, and the answer seems to be at least five. And you see these chin anes of parasites in gal wasps. So a gal wasp, the basic gal wasp, is a species of keeeny tiny wasp that forms a gall on

a plant like an oak tree. What a gall is it's a bulb of flesh that the plant or tree is induced to create that does not benefit the tree, but it benefits this wasp. So the wasp will drill a hole into the bark or skin of the plant. Sometimes these galls are created on leaves and stuff, but we're focusing on an oak gal wasp. So it drills into the oak's flesh and then this bulb forms and the gal wasps will lay it's a inside of this bulb that is formed from basically this chemical that the

larvae excretes. And then this bulb that grows around the larva has a fleshy interior that the larva feeds on, So it's feeding on the tree. It's harming the tree, and so that is why it is a parasite. Now there are other gal wasps that then take advantage of the previous gal wasp, the gal wasp that created this gall, this bulb, and then it lays its own offspring inside the other gal wasps gall. So it will sometimes harm

the larva of the previous tenant of this gall. Sometimes it won't prevent it from developing, but it certainly steals resources from it. And then you have parasitoid wasps like the crypt keeper wasp. Remember a parasitoid necessarily kills its host. So the crypt keeper wasp will lay its eggs inside the gall on top of an existing larva, and those eggs will hatch into carnivorous larva which will feed on

the other gal wasp slowly. Again, the sort of distinction between a predator and a parasitoid is a parasitoid feeds slowly on its host over a long period of time

before killing it. So this parasitoid gal wasp will feed on the host larva and then it will continue to consume this victim larva slowly, and as the victim larva grows and develops into an adult wasp, the parasite larva will compel it to drill its way out of the gall, and then at this point the parasite will actually be head the host gal wasp, and that head blocks up the opening to the gall and basically creates a fleshy door.

And then once that parasite larva continues to develop into an adult, it can then just basically eat its way through this head and emerge from the gall, so you can have chains of Basically, the first layer of parasitism is the initial gall creating wasp that is a parasite on the oak tree, and then you have maybe a gall wasp that is a parasite and infesting this gall by stealing essentially the resources from the gall from the bulb itself, and then another type of parasite that will

steal resources directly from the larvae, eat them, consume them, a parasitoid, so you could actually get chains of this, and apparently it's been observed to be up to around five levels of parasitism, so things get wacky with these gall wasps, really interesting. So the point of giving you all these examples is to demonstrate the wide variety of parasites and parasitic strategies, which gives you a sense of

why there are so many parasites in the world. There are near endless opportunities for parasites to take advantage of, and typically when there is a niche say there's some form of nutrition that can be exploited, there will be an organism that, over millions of years evolves to exploit it.

We have limited resources on the planet, there's a lot of competition for resources, so finding shortcuts or cheets can greatly enhance an animal's success, and of course the host animals are also forced to develop strategies through evolution to try to counteract the parasite's attack. So in terms of what good they do for the ecosystem. By definition, parasites are bad for the individual host. There is no good parasite for an individual, but for say an ecosystem, they

can actually be critical. So an ecosystem is a whole group, a delicate chain and web of animals interacting with each other, and so even though a parasite may harm an individual, they could provide a benefit to the ecosystem. So, for instance, nutritional biomass mosquitoes provide a huge biomass for other animals to feed on. There's potential for parasites to keep certain species from growing too numerous two dents which can maybe

help with plant growth. Say you have you know, too many deer or too many rabbits or something, and they're too dense. Much like how predators will help keep these in check, parasites can also help keep them in check. And this can help prevent say, plants from being devastated by too many herbivores or you know, it could keep predatorspecies in check, and then that helps prevent too mini

predators from going around killing herbivores. So it can keep some of these things in balance, and it can also increase the biodiversity of the host species through selective pressures. If you're a parasite and you're putting selective pressure on your host, you may force it to adapt in some way, and this can actually result in speciation, so a new species arising from this. So this can increase biodiversity, increase genetic diversity, which is really important in a changing world

where you may have certain shocks to an ecosystem. So having more genetic diversity prevents a species from say, being wiped out by a change in the environment. Because you have such a rich genetic library, you might be able to adapt to this change. So removing parasites from the planet I think would be very very harmful, would be devastating because it would weaken this intricate web. I like to call it like a Jenga tower, these complex interspecific

relationship between different species. And you remove one piece, maybe it doesn't do anything, but if you remove it, it could also make the whole tower collapse. So parasites very important for an ecosystem, very harmful for an individual. But I love them because they're so weird and their strategies are so intricate, and it's almost spooky sometimes how good they are exploiting. So we're going to take a quick break, and when we get back, we are going to answer

another listener question. All right, onto the next listener question. This one says less of a question and more a layman's observation. Maybe you've covered it before. Kind of unusual, how frogs don't have teeth yet eat flies, making them omnivorous. Right, and this is from Sherman. So Hi, Yeah, So some frogs are omnivorous, meaning they eat plants as well as

meat or other things. So omnivores eat a variety of different different fruits, usually meat and plants, maybe fruit, maybe nuts, seeds, whatever. So some frogs do eat both plant matter and insects. But if a hypothetical frog I'm among which there are many species that only eat flies or only eat insects, it would make it insectivorous. So insectivores are a type

of carnivore, a carnivore that specializes in eating insects. So some frogs will be omnivores, some frogs will be insectivores, or some will be carnivores because they can eat both insects, small mammals, other frogs It kind of depends on the frog size. Frogs really love to basically eat anything can can fit in its mouth. Frogs typically aren't super picky when it comes to live prey as long as they

can fit it inside of them. So onto the teeth. Uh. Now, it's true that frogs do not have a prominent visible set of teeth, but not all frogs are toothless. Some are, and almost all frogs lack lower teeth, but there are many species of frogs that have tiny upper teeth or teeth on the roof of their mouths. Frog teeth are really teeny tiny. They are not easily seen with the naked eye. You usually have to use a CT scan of a skeleton or microscopic photography in order to see

these teeth. But in terms of frogs that have both an upper and lower set of teeth, there's only one known species of frogs that have this. This is Gunther's mare supial frogs. They have a set of upper and lower teeth, all extremely tiny teeth about the size of a grain of sand. So this is really weird that this is the case for Gunther's marsupial frogs because these frogs lost their lower teeth two hundred million years ago along with these other frog species that don't have lower teeth.

But it has re evolved these lower teeth, which it's unclear exactly why they have. It's really fascinating that that they can re evolve these teeth after so long. But it likely has something to do with grips. So you know, you think of sand paper, right, even though these teeth are the size of a grain of sand. With sandpaper, it's got a lot of traction, it's got a little grip.

So it's thought that with frog teeth, whether they only have an upper set or they have that upper and lower set, has something to do with providing some friction to keep struggling prey from escaping, especially when it comes to larger prey. So, in fact, there are some species of frog that have developed a set of lower things that kind of look like buck teeth, but really these

are bony projections. They're not teeth. They lack dentin. True teeth has dentin, whereas these bony projections kind of look like little things, but they are not true teeth. But yeah, you do not need teeth to be a carnivore. So examples of other carnivores that do not have teeth. Giant ant eaters do not have teeth. Their jaws barely function. Instead, they rely on a long, sticky tongue to capture and slurp up ants and termites. Similarly, pangolins have no teeth.

Pangolins are those little living pine cone like animals. Well they're not that little, actually, they're definitely an armful, but they have those scales that kind of look like a pine cone, and they feed on ants and termites, but they don't have any teeth. They just have, you know, a tongue and kind of viscous saliva. Pangolins will also eat stones to help pulverize food in their stomachs. Stones that are eaten in order to help with digestion are

called gastroliths. Pangolin stomachs are also lined with spines, which help further macerate the insects they eat. So even though they don't have any teeth in their mouth, they do have ways to crush insects in their gizzard, which is interesting because this is a strategy also used by birds. Of course, birds do not have teeth. There are some birds, especially filter feeders, who will have kind of tooth like

ridges in their beaks, but they're not true teeth. But most many, many species of birds don't even have these. They rely instead on their beaks. They can be really sharp, they can be shaped differently in order to achieve different kind of things, but they don't have teeth, and they, like the pangolin, will actually sometimes swallow stones or sand in order to help with digestion in their gizzard. Of course, beaks are also used by octopuses and squids, who are

also carnivores, and they don't need teeth. They use these beaks along with their tentacles in order to entrap and rip up and eat prey. Another one of the world's biggest carnivores, in fact, one of the biggest animals. The biggest animal in the world has no teeth but is a carnivore. These are toothless whales, baylean whales, who use these broom like balen to sift out huge amounts of krill, which they gulp up. I know it's weird to think of a baling whale as a carnivore, but they are.

They eat krill. Krill is a living animal, it's meat. They will eat so many of them. They are actually really really good carnivore, very very high number of prey that they can get all at once. But yes, despite their prey being so small, baling whales are carnivores and they don't have to use teeth to do it, and they are the world's largest animal. So teeth are important for us though, so brush them. You know. It's not like we can put brooms in our mouth and use

that to filter soup. I mean, maybe we could. I don't recommend it, though, Keep those teeth brushed and flossed, and you know, like drink a lot of water. Anyways, We're gonna take another quick break, and when we come back, I'm going to answer the last listener question. Next listener question. Recently, orchidmantis species have been shown that was once thought to only be camouflage for mimicry are actually gliding surfaces too. What are your favorite surprise animal abilities only found years

after the species was known and studied. This is from URF the MIRF. This is amazing. So orchidmantises, which are beautiful, beautiful insects. They are a species of mantises that look like orchids, I mean the name is truly accurate. They have pinks and whites and green colors, and they have all of these like petal like protrusions, and they have these petal shaped lobes on you know, basically their their legs, and it looks beautiful. It makes them look like an orchid.

It helps with their camouflage so that they can be both protected and an ambush predator, which is really cool. But the new news is that they can also use them as gliding surfaces, essentially, like because the surface area has increased, they can glide for short distances using these petals, which can also be used for camouflage, which is just beautiful and fantastic. Other discoveries of animals that we've known

about for a really long time. I love it when there's like a I don't want to say mundane animal, because I think they're all really interesting, but an animal we know, it's well known, and then suddenly something new pops upwards we had no idea. One of the things that I think is really funny is we keep discovering that so many mammals biofluoresse, have biofluorescence, and we don't know why. So it started out with a few discoveries

of mammals being biofluorescent. So biofluorescence means that they absorb and re emit light. You can't see this with the naked human eye, but you can see it under black light. So this was discovered in apossums, flying squirrels, and platypuses and they were found to be biofluorescent. And then researchers started testing more mammals under black light. They did this with specimens in museum or research catalogs, so they kept finding more and more species who were biofluorescent, and the

list kept getting longer and longer. So wombbats, bilbies, armadillas, red foxes, dolphins, cats, house cats, bats, zebras, big cats, they all were found to have biofluorescent fur or other body parts. In fact, one hundred and twenty five species of mammals were found to biofluoresse when Western Australia Museum puts specimens under UV light. So it's still not really

well understood exactly what is causing this. The emerging pattern seems to be that nocturnal animals have stronger biofluorescence, but this is still something found in diurnal animals animals that are active during the day. So another pattern I guess is that white fur seems to be more likely to

be biofluorescent. So like in the case of housecats, only white fur has been found to be biofluorescent, it's the only type of fur that does so, but in other species of animals, like there can be other colorations of

fur that is biofluorescent. So yeah, it's really interesting. We kind of had no idea that this was a feature for so many mammals, and so it's I'll be keeping my eye on this for sure to find out if they come up with any more hypotheses or do any more testing to figure out why exactly this is the case.

Is this just a basically like a evolutionary spandrel something that serves no function but it's just it just happens to be there and it's cool, or does it serve some kind of function, So yeah, it's very very interesting. Another thing is I love it when we make new discoveries about ants because ants are so common and they're everywhere, and it feels like we already know everything about ants,

but then ants always surprise us. So of course there are many different ant species, so Just because we know a bunch of things about one ant species doesn't mean we know everything about all the ant species. But still it's really cool when we discover new things. So there is a species of ant called the Indian jumping ants, which are found in India. They are really interesting looking ants with elongated mandibles, and their colony structure is a

little different from most ants. They have pretty small colonies, about one hundred individuals. They do have queens, but the queen's position is a lot less secure and high up on a hierarchy than in typical ant colonies. You see workers that can rise to become queens and workers that can control who is their queen. So if there is a queen who has not been approved of by the colony, she can be dethroned and placed in queen custody, where

a very weird body transformation can take place. So when an old queen dies in one of these Indian jumping ant colonies, the queen is selected in a jousting competition. Yeah, this is very medieval or Middle Ages. I'm not a historian. So they have those elongated manibles that I talk about, and they will essentially joust with each other until there is a clear dominant winner. That winner will become the new queen. And what happens when you attain power, Well,

your brain shrinks and your ovaries expand. So yes, the queen's brain will shrink and her ovaries will expand, and she assumes the position of being the breeding dominant queen. But if there is multiple ants that are starting to develop into queens and one is unauthorized, or if there's a queen that is not performing her royal duties correctly, the worker ants will seize her into a restrictive hold. They don't kill her, though. Ants are more civilized than

humans are. When they are deposing a queen, this ant is just held until its brain expands and ovary shrinks and it biologically turns back into a worker. So it's kind of like a representative monarchy, democratic monarchy. It's a very violent one, but maybe not as violent as people. I'm just saying the ants may have some things figured out, you know, except for the part where their leader's brain shrinks. It's not like that happens with humans anyways. I really

hope that you enjoyed this Listener Questions episode. If you want your question to be answered. You can write to me at Creature feature Pod at gmail dot com. You can write to me on Twitter if you dare delve in that murkiness. I'm still Katie Golden. There a T I E G O L D I N. And I will definitely keep doing these listener questions episode because I love answering your questions. It forces me to do research on topics sometimes or study up on things I've forgotten,

so it's a learning experience for me as well. Help me help you, help me help you to learn. Yes. Anyways, hope you're all doing well. Thanks to the Space Classics for their super awesome song Xolumina. Creature features a production of iHeartRadio. For more podcasts like the one you just heard this, the iHeartRadio app, Apple Podcasts, or Hey guess what wherever you listen to your favorite shows. I'll see you guys next Wednesday.