The Science of Everything Podcast - Episode 70: Animal Diversity Part 2

Episode Date: December 30, 2014

Continuing from Episode 69, I explore the diversity of the mammals, looking at all the mammalian orders and their major families. Special focus is given to primates and particularly hominids, which are discussed at the species level. If you enjoyed the podcast please consider supporting the show by making a paypal donation or becoming a patreon supporter. https://www.patreon.com/jamesfodor https://www.paypal.me/ScienceofEverything

You're listening to The Science of Everything podcast, episode 70. Animal Diversity Part 2. And I'm your host, James Fodor. So this episode continues directly on from the previous episode, unsurprisingly, Animal Diversity Part 1, where I went through and discussed the diversity of the animal kingdom right through and looked at all the different filer. And particularly, I also focused on the orders within the chordate phyla, which is where humans sit. In this episode, I'm going to move on to talk about our favorite.

class of chordates, which are the mammals, 5,500 species, and we'll be going through these in a rather a bit more detail than we have been for the other classes, because obviously humans are mammals and most of the animals that we sort of know about and are familiar with are also mammals, and so I think it's a bit particularly useful to have an understanding of how the mammalian class is structured and fits together. So I'll actually be going through all of the main families of the mammalian class, which is actually fairly low down in the taxonomic hierarchy. If you recall, family is the second lowest level of, classical level of classification, just above genus and then species.

Okay, so let's make a start. If you perhaps recall from having herb before, mammals are essentially animals that have fur and suckle their young. They give birth to live young, which they then suckle, as opposed to birds and reptiles and amphibians which lay eggs, except when mammals don't, which brings me now to discussing the first main group of mammals, which is actually a subclass, and these are the monotremes. Monotremes are a very special, strange order of mammals, so this is an order within the class of mammals. The echidna and the platypus, each of which have their own family, found in Australia,

and they were a very big surprise when they were first discovered by Europeans because it was thought that mammals don't lay eggs. They give birth to live young. But echinors and platypuses are the exception because they do lay eggs, but also have many of the other characteristics of mammals. So there are a strange sort of cross-combination there, and that's why they're given their own order monotremes. But only two species in that.

Moving on to the next main branch of mammals, which is sometimes called an infraclass or a subclass. I guess it doesn't really matter for our purposes. We might call it a subclass. It's like a subcategory within the mammalian class. Metatheria. And these are the marsupials. So they carry their young in a pouch.

And these are mostly found in Australia and South America. Also some in New Guinea, I believe. There are several orders of marsupials, about 330 different species in total, so much fewer than the total number of mammal species, but still a fair amount of diversity, certainly much more than the monotremes. Before we dive into the marsupials, however,

I just want to introduce the other main sort of subclass within the class of mammals, which is called euthyria, and these are the placental mammals. So these are mammals where the fetus is nourished using a placenta, which is different to how it's done in marsupials, where the young are nurtured, inside the pouch. So that's the main difference between the Metatheria subclass and the subclass

of the Eutheria, or the placental mammals. Most mammals that we know about, or the, you know, we're familiar with are placental mammals, about 5,200 species, and then there's maybe 300 or so species of marsupials, and then, in addition to that, there are the two species of egg-laying mammals in the subclass called Theria, or, as we said before, the order, monotremes. So those are sort of the three main big groups of mammals. But most Most mammals do fit into the class of placental mammals, so that's what we'll spend most of our time talking about. We've already discussed the monotremes, the weird exception egg-laying mammals, platypoles and echinor. Now we're going to dive into a little bit more detail into the methamphetoria, the marsupials.

So there are maybe half a dozen or so major orders, again about 330 species in total. One order has about 100 species and constitutes the oposs. So these are, well, small marsupials look a little bit like possums that are found throughout the Americas, particularly South Central America. There's also a couple of other small orders with a handful of species, also found in the Americas. Bandicoots and Bilbe's in particular have their own order. Another one, shrew-o-possoms, also found in the Americas, has its own order. So a few orders of opossums or similar small marsupial creatures. The two main orders of marsupials, the first of those,

is basically the most of the carnivorous marsupials are in the first order, and most of the herbivorous marsupials are in the second order. So the first has about 70 species. That's the Desiria morphia, whatever it is. About 70 species. Most of the carnivorous marsupials are in that one, and the diprotodontia. Most of the herbivorous marsupils are about 120 species.

So again, we see a classification based on sort of behavior and morphology in this case. There are three families in the order of the, carnivorous marsupials. One family is, constitutes the phylusenes. You may have heard of these. The Tasmanian tiger is the only species in this family that existed in recent times. It's not actually extant anymore. It went extinct in the 1930s. The last individual died in a Hobart zoo, I believe, in the early 1930s, although there are reports that it's been cited more recently than that, but it's generally thought to be extinct. I'm quite an interesting animal. It has its family in the order of carnivorous marsupials, thylacines. There's another family with one species

of Numbat, which again is a sort of small wombat-like animal found in, I think it's found in Australia. And then, but most of the species in this order found in a family which is, which has that, basically the Tasmanian devil is probably the most well-known animal that fits into that family. There's a few other things as well, Qualls and Dunnarts and other things, which I haven't really heard of. But the Tasmanian Devils, and there's a variety of different species of those fit into their family there. So that's the order of carnivorous marsupials. And then if we jump to the diprotodonsia, the herbivorous marsupials,

there's more families of this. There's maybe 10 or so, 10 or 12 different families within this order, so a bit more diverse. So by far the largest family in this order of herbiferous marsupials is with about 60 species, that which contains the kangaroos and the wallabies, the hopping marsupials found in mostly in Australia, I think also some in New Guinea.

So most of the diversity, or about half of the species of herbivir, as marsupils are kangaroos or wallabies, so quite a lot of those. Also, there are a number of different species of possums, actually, and they fit into quite a number of different families. So there are brush-tailed possums in one family. There are pygmy possums in another family,

ring-tailed possums in another family, and then one family, again, has a number of possums that are probably familiar to Australian listeners, The lead beeters possum, yellow-bellied glider, sugar glider, squirrel glider, and striped possum. They're all in their own family. The honey possum is by itself in yet another family, and again, I'm not going to bother with the names of these families

because I can't pronounce any of them. And the feather-tail glider and feather-tailed possum, two species in their own family. Again, so most of the... Take over from that is most of the different families within the order of herbivorous marsupils are various forms of possums, and so there's several dozen different species of possums.

maybe 50 or something put together. I already mentioned the family containing the kangaroos and wallabies. So what's left? There's another family which contains rat kangaroos and bettongs and another animal called potteroos. Basically they're kind of

like small kangaroos, about eight species of those. They're a separate family to the main lot of kangaroos and wallabies, but sort of fairly similar in terms of morphology. But what does that leave if we take out the kangaroos and the wallabies and then the small rat kangaroo versions and then all of the different types of possums. There are two families left.

One family contains a single species, and that's the koala, which I'm sure you've heard of, and another family contains the three species of wombats. So they exist sort of by themselves, as distinct animals. So if we're talking about marsupials, basically we've got the carnivorous marsupials in one order, which include Tasmanian tiger, numbat, and Tasmanian devils. And then in the another order, we have the herbivorous marsupials, basically kangaroos, wallabies, possums, and then your koala and your wombats. There's also one other order of marsupils, which I don't think I mentioned, and they contain two species called the marsupial moles,

which I guess are a little bit like wombats, but not quite the same thing. So that's the marsupials, about 330 species in total. Again, they carry young in their pouch, as distinct from the placental mammals, which use the placenta to nourish the fetus. As I mentioned before, marsupils are only really found in Australia, New Guinea, and South Central America. and so their diversity is much less than that of the placental mammals, which have most of the diversity of the mammalian class.

So that's what we're now going to move on to the placental mammal, sort of the real mammals, as you might sort of say from an anthropomorphic perspective. These are the mammals that are most closely related to humans. Okay, so how many mammalian orders are there in the, subclass utheria or the placental mammals. About 15 or 16 or so, so about 15 or 16 orders, which is a fair bit of diversity, although that is a fair bit smaller, say, than the number of orders of birds or the number of orders of bony fish, for example, which exceeded 20 or 30. So a fair bit of diversity in placental mammals, but not as much as some of the other classes

within the phyla of chordates. But anyway, let's talk about what these different orders are. I think what I'll do is go through them in order of the diversity, with a couple of exceptions. So that is the number of species within each order. So by far the largest, sorry, not quite by far, by a reasonable margin, the largest order of placental mammals is called Rodentsia. And basically these are the rats and the mice and beavers hampers, that sort of thing. So rodents, essentially. There are over 2,300 species of rodents. So almost half of all placental mammals, maybe 40% of all placental mammals,

rodents of one sort or another. So a great deal of diversity there. There are lots of families, maybe 20 or 30 different families. I remember that's the one just below order. Families within the within Redentia. Some of them small, some of them large. I'll just talk about, mention some of the main ones. One of the largest ones is a family of 600 species, which contains hamsters, muskrats and voles. So hampsters and voles are of course rodents. I mean, that's not terribly surprising. Lots and lots of different species and a lot of diversity. There's 600 in total. I mean, that's more than, far more than, say, the total number of primate species, even though primates is an order, whereas we're just talking about a single family here. Another big family

are Muraday, which is the true mice, rats and gerbils, so they're closely related, about 700 different species of mice, rats, and gerbils. Some other interesting inclusions. The Mountain Beaver has its own family, only one species in that family, but then there's 285 different species of squirrels. There's also another family which are just ordinary beavers, as opposed to the mountain beaver. Two different species of those. There's another interesting family composed of about 60 species of kangaroo rats and kangaroo mice. This is so-called because they kind of look a bit like kangaroos,

but they're not actually marsupials. They are placental mammals. So they're sort of misnamed to a degree. And again, this is where it can be useful to have an idea of taxonomy, because an animal might be called a kangaroo rat, even though it's actually not really that closely related to kangaroos. There's another fairly large family of species, which include climbing mice, rock mice, and wild-tailed rats.

37 species of mole rats and bamboo rats. 29 different species of dormice. Porcupines have their own family, about 11 different species. Oh, I should say, sorry, actually, there are two different families of porcupines. One, old-world porcupines and another new-world porcupines. This is a distinction that you see or a classification that you see occasionally in the taxonomical system. You see it with monkeys as well, old world and new world monkeys.

The old world basically refers to Europe, Asia and Africa, which is the sort of old world from the perspective of Europeans or Middle Eastern peoples, the landmasses that they knew about. The new world is, of course, the Americas, which are split off from the Afro-Eurasian landmass. and so the old world refers to Afro-Uasia, Eurasia and the new world, the Americas. And so that's a distinction that's often useful to know about in taxonomy, because it's often because those landmasses split off from each other tens of millions of years ago,

although they have been land bridges more recently than that, but the landmasses have been more or less distinct for quite some time now. There has been a fair bit of divergence evolution between those two landmasters. So often there'll be one branch that sort of evolved in the Americas and one which evolved in Afro-Ura-Uraja, hence why we need to distinguish between old world and new world versions of certain species. And porcupines are one example of that. So there's 11 species of old-world porcupines and 16 species of new world porcupines. Another interesting family in Roedentia are cavies or guinea pigs.

They're not really pigs. As you might note, pigs will come up later, but they're in a different order. Guinea pigs are more closely related to rats than they are to pigs, so the name's a bit misleading. 13 species of those. quite a few other families of rodents which honestly I'd never even heard of before including chinchilla rats, spiny rats, hoochers, river rat, tuku, or all sorts of weird and wonderful things it's also interesting to note how different these sorts of classifications are again and this is a point I made before to how we might naively classify things like for example it's not the case that all rats

are in the same family there's one family that has most rats and the true mice but then there's a few other things that are called rats, like comb rats, for example, or African mole rats, or cane rats, dacly rats, which have their own families. So they're not true rats. And this is a case, this is similar to what we saw earlier when, for example, when we talked about bugs in the arthropods, there's one order, I think, which is comprised of true bugs, and then there's other things which are kind of called bugs, but are not actually bugs, strictly speaking.

So that's another very common thing that we see in taxonomy. It's useful to be aware of. Anyway, I think that's enough said about the rodents. Let's move on now and talk about the second largest order of placental mammals. Remember, 5,200 species, and we've already accounted for 2,300 of them in the rodents. The next largest order has 1,100 different species, and these are the bats. There are 20 families of bats, so lots and lots of different types of bats. Again, very diverse type of animal.

And this also illustrates another point, which is that the words that we tend to use to refer to animals are quite different to, that they don't reflect very well the diversity within that type of animals. So, for example, many people could name all sorts of different types of dogs or cats, but actually all domestic dogs and cats are the same species, whereas most people probably only know maybe a few different types of bats at most. But actually, there's over a thousand different types of bats. So having, we know, one word for bats and lots of words for dogs is not really comparable in terms of. of the actual biological diversity. So it's useful to be aware of where the diversity lies and where it doesn't lie. In the case of placental mammals, much of the diversity lies in rodents and bats. Now, some of the larger families of bats include freetailed bats.

About 100 species of those, they're found in the new world. There are 300 different species of Vesper bats. Those are found worldwide. Old world fruit bats, which are one that you may be more commonly. There are 186 different species of those. just to put that into some context that is comparable to the number of species

of cats, dogs, bears, seals, weasels, skunks, hyenas, badgers, otters, weasels, raccoons, and a bunch of other things, all put together. All just in one little type or one single family of bats, old world fruit bats. So, an enormous diversity where you wouldn't necessarily expect it, even in the placental mammals. backwing bats, a tropical species, a tropical family, I should say, have 51 different species.

There's an interesting type of rat called the bumblebee rat, which is a really, really tiny rat. It's not quite as small as a bumblebee, but it is very, very small. There's only one species, and it's quite critically endangered, I understand, but quite an interesting animal. There are some other smaller families, moustache bats, bulldog bats, New Zealand, short-tailed bats, Madagascar bats, disc wing bats, smoky bats, funnel-eared bats, old world leaf nose bats, I already mentioned those, false vampire bats, just many, many different types of bats. Fascinating to see the diversity here. Most of the families have, you know, a dozen or 20 or so species in them, some of them only one or two, others, you know, 100 or so. Largest one, as I mentioned,

300 species of Vesper bats found worldwide. One thousand hundred species overall in the order, so a great deal of diversity to be found there. So between just the rodents and the bats, we've already accounted for 3,400 of the 5,200 placental mammal species. And that's only two of the orders, of the roughly 15 orders. So let's move down the list. The next most populous order are the insectivores. There are about 540 different species of insectivores,

and these are animals like moles, shrews, and hedgehogs, basically, that eat insects. So again, you might not have sort of realized there were so many of these types of animals, but there are, in particular, a single family in this order has most of the diversity about 376 different species of shrews. Shrews alone, 376 species, just amazing. Some of the other families include golden moles, which are distinct from moles and shrew moles. Those are in separate families. And there are also another family containing an animal called tree shrews, and yet another called called, containing animals called elephant shrews.

So many different types of shrews. True shrews in the family that contains most of the shrews, and then there's other things called shrew moles and elephant shrews. So mostly shrews. Hedgehogs are found in their own family. They're about 24 different species of hedgehogs. And there are a few other families in there as well, about eight or nine in total in insectivore, the order.

So basically moles, shrews and hedgehogs eating insects. Moving down the list, the next most populous order is that of the carnivores, carnivora, which has nearly 300 species. Now, this order really contains a lot of different types of animals, at least as far as we would sort of naively classify them. That is, if a person was asked to write a list of animals, then probably a lot of the animals that they would write down would be found in this order here, of carnivores. also probably a few from the next two orders that we're going to cover here. But there are only 280 species, which is about the same as some of the families of rodents or bats. So it's interesting how the diversity plays out with our familiarity with them.

But this order of carnivores is a little bit misleading because it doesn't actually... Not all of the animals in this order are actually carnivores. That is, they don't all eat meat. Most of them do, but not all of them. and so the name is really based on the fact that they're sort of descended from animals which from an ancestor which was a carnivore and many of them are carnivores but they're not necessarily carnivores just because they're in this order which is a little bit confusing anyway so what is in this order there's perhaps a dozen or so many of families in this order and you might be sort

of surprised by what animals are grouped in here because so far let's think about the orders we've had so far in placental mammals we've had insectivores okay you know shrews moles hedgehogs I You can sort of see those fitting together. Bats, of course, yes, those fit together, and then rodents. So, moles, sorry, rats, mice, squirrels and beavers, those sort of fit. This family of carnivores has at least what would seem to us to be much more diversity. So the first family in it is the largest family consists of badgers, otters, weasels, martens and ferrets.

So at least to me, I was quite surprised to see that badgers fit in alongside otters, weasels, and ferrets. but they do. About 57 different types of species, of those different types of species all put together. And those are just in one family, so they are quite closely related. Badgers are quite closely related to weasels and ferrets, interestingly enough. The next largest family within that order is what we might call the felines. About 40 species of, well, cats essentially, including lions, tigers, jaguars, leopards, lynx, puma, cheetah, and the domestic cat, as well as some various other types of cats that are less well known. Remember, the domestic cat is only a single species of the, a single one of the 41 different species of cats that there are. Most of them are larger and more fierce.

So quite a lot of different species there. And it's perhaps not so surprising that those are, you know, related to the otters and the weasels, because they're kind of similar. There's another family of sort of cats that live in trees, Gennets and Civets, or not quite try to pronounce that. About 30 different species there. There's about 34 different species of mongus, which, has their own family. Another grouping, another family in the order of cats is the hyena, four different species of hyena.

And as you might expect, the canids or the canines, are also in this family, quite closely related to cats in the same order. About 35 different species of dogs, wolves, jackals, foxes and dingoes. Domestic dogs descend from wolves. It's thought that they were first domesticated something like 17,000 years ago. So they are quite closely related to wolves. Another family that fits in here are the bears. So this includes the black bear, brown bear, polar bear, and also pandas. Now, pandas are an interesting one because they are not carnivals,

although occasionally they have been seen to eat meat, but mostly eat bamboo shoots, even though they are quite closely related to other types of bears, and they are fit within the same order, carnivores, as lions, tigers and hyenas and cats and dogs, which wasn't obvious to me. But perhaps the biggest surprise in this interesting order here are the seals, which actually also fit into the order of carnivores. This game is kind of a shock to me because I had no idea that seals and also sea lions and walruses, all of them are in the order of carnivore. There's about 15 different species of sea lions and fir seals, about 20 species of seals and one species of walrus.

All of them have, all of those three have their own families within the order of carnivores. and they're also fairly closely related to cats and lions and tigers and so on, because they're in the same order. If you look at a picture of a seal, you can actually sort of see how it looks a bit like a cat. It sort of has the whiskers in the same way. So, very interesting example of how we can improve our understanding of sort of a layperson's understanding of the relationship between different animals by studying taxonomy. Because at least what I would have thought is that seals would be more closely related to dolphins and whales. But they're not. They're more closely related to cats and bears.

very interesting. Oh, one final family in Carnivores that I forgot to mention is the raccoons and ringtails and a few other things, about 14 different species of those, they have their own family as well. So basically, carnivores includes cats, dogs, bears, seals, weasels, skunks, badgers, raccoons, hyenas, quite a different mix of animals and about 280 species in total, as I mentioned before. Now the next two families kind of fit together, but they are, excuse me, the next two orders kind of are related to each other, although they are distinct orders. That's why I've put them together. One has all of the even-toed-hoofed animals and another the odd-toed-hoofed animals. The first order has about 220 different species, the even-toed hoofed animals, and the next one is only about one-tenth of the size, about 20 different species. The odd-toed-toed hoofed animals.

And you might think it odd that whether the number of toes is even or odd is something of significance that we would base classifying animals on. But actually, this is exactly the sort of morphological difference, which certainly traditional sort of Linnaean taxonomy looked for when deciding where to 15 animals. This is a, well, it's useful in terms of making a distinction, but also it does, these sort of things do tend to track evolutionary relationships. Anyway, let's start with the even-toed-hoofed animals.

and if that's unclear to you, this, I mean, literally just does mean the animals have a hoof, which has an even number of toes, as opposed to animals that have hoofs, was an odd number of toes, and you'll see what I mean there when I give some examples. So by far, the even-toed-hoofed animals has more diversity. There's maybe 10 or so families in this order. The largest is bovids, which is basically cattle. There's 140 different species of bovids. This includes Bison, bison, buffalo, antelopes, gazelles, sheep, goats, and cows, other types of cattle.

So quite a wide range there. The next largest family within this order consists of deer, which includes elk, moose, reindeer, and other types of deer. Now, I can't remember if I mentioned this before, but I'll just mention it again now because it's relevant here. Within the family of bovids, antelopes are an example. of a waste bucket taxon, if you recall I mentioned that earlier, where you just sort of throw a whole bunch of leftover species into a single category because they don't sort of fit anywhere else. Antelopes are an example of that, because within bovids,

you have the Beeson and the buffalo and the gazelles and the sheep and goats and cattle. You separate all that out. Whatever's left over just called antelopes. And so most bovers are actually antelopes, and that's just because antelopes is a catch-all tax. And it actually doesn't have a very precise meaning. So, again, useful things to learn from taxonomy. some of the sort of lay terms we used to describe animals

actually refer to very specific animals, like examples would include the platyposed and the echidon, where there's only one species or maybe a couple of species. Pandas would be another one. Hippopotamus, as we'll see, there are only two species of those. Others like antelopes refer to a wide range of different species and really aren't, don't refer to a very specific thing, that's just sort of a catch-bag, a catch-all bag.

Anyway, that's the bovids. Also, interesting inclusions in this order include the family, which includes domestic pigs, wild pigs, and warthogs. There's about 16 different species of pigs in total. Then there's a separate family of new world pigs. So again, we see this distinction here between old world pigs and new world pigs, 16 and 4 species, respectively, split up into two different families. You recall we saw that with one of the species of bats,

and we'll see it again with monkeys as well. Some interesting conclusions here, some of the other families, there are two different species of giraffe. Well, actually, there's one species of giraffe, and then another species called Ocopi, or Ocopi, I haven't actually heard of those before, Ocarpe, which are in their own family. There is also the family of Camelidae, or whatever it's, however it's pronounced, which includes six species of camels, lamas and alpacres.

Again, even-toed-hoofed animals, this is the order we're looking at, so if you think about all of these animals, you can sort of imagine that they have hoofs with an even number of toes. And probably one of my favorites, the family that contains the hippopotamus and the pygna hippopon. So a fair bit of diversity inside even-toed animals. Basically, a lot of animals that are used for domestication and food, livelihood throughout history. So particularly, you know, the basin and buffalo, sheep, goats, also camels, llamas, alpacas, domestic pigs, wild pigs, new world pigs, not really so much the giraffe or hippopotamus. So quite a lot of the sort of what you might think of as farm animals fit in.

into this category here of even-toed-hoofed animals. As I mentioned before, the sort of corollary or counterpart to the even-toed-hoofed animals order is the order of odd-toed-hoofed animals. There are only 18 species in this order, so it's a fairly small one. Three families. One family includes five species of rhinoceros, another family, four species of tapir, and tapir, and nine species of horses, donkeys, and zebras. So, horses are probably the easiest to visualize in terms of what we mean by

odd toad because clearly, I mean, horses essentially have a single toe. It's really multiple toes sort of fuse together into one hoof, which is different to how it works for, you know, pigs and cattle and other animals in the odd toad. I should also mention that these types of animals are called ungillots. They are animals that have hooves. So we can talk about even-toed ungulates and odd-toed ungillots is another term you might hear. Okay, so that's those two orders finished with. Let's now move on to talking about one of the next most populous orders, cetaceans. There's about 90 species

in this order, and these are the whales, dolphins, and porpoises. There's maybe eight families here, and this includes 33 species of marine dolphins, and that's a fair bit of the diversity in the order here, 33 species of marine dolphins.

But there are also river dolphins, which have their own sort of family, and porpoises, six different species of those. And then the rest of the, the rest of the families in this order consist of different types of whales. So, one family

has nine species, and these are the Rorkel whales, not quite sure how to pronounce that, which has nine species. The blue whales are included in this family here. Another family has only one species, the grey whale. Then there's the bowhead and right whales, which have their own

family. Sperm whales, three species of those. Beaked whales, 21 species of those. And there's also So two species in a family, which consists of the gnar whale and the beluga whale. So quite a number of different types of whales all split up into different families, whereas most of the dolphins are contained within only a couple of, only two families, plus the porpoises which have their own family.

So a fair bit of diversity in whales, although not nearly so much as, say, in bats or rodents. As I mentioned, 90 different species of cetacea. I probably should mention that hopefully most of you are familiar with the idea that dolphins and whales and porpoises are mammals. They give birth to live young, they breathe air, they have fur and so on. Some people think of them as fish, but that's incorrect. They're certainly not, well, they're not the invertebrate type of fish that, you know, I mentioned at the very start of the podcast that are in completely different phyla, but they're also not either ray-finned or lobe-finned fish, which are in a separate class outside of mammals. So whales and dolphins are

more closely related to, say, humans than are other types, well, than are fish proper. And it's also interesting to note, as I mentioned before, that seals are not particularly closely related to whales and dolphins, although they are both aquatic mammals. They are in different orders, and so they split off from each other a fair while ago. Okay, that's the cetaceans. Now we have an order containing 80 different species called Lagomorpha. This has the lagomorphs. These essentially...

Lagomorph basically means animals that are adapted to... Well, it means plant eating, but it's... The idea is sort of more gnawing or chewing. So, if you imagine a rabbit with large front teeth, which is nibbling on a carrot,

that's essentially the idea of lagomorfer as an order. It's animals like that that have big teeth and sort of gnaw on plant matter. Basically, it's hares, rabbits, and pika. Peaker are kind of like rabbits, really, they have one family with about 30 species, and then there are the rabbits and hares, 50 different species in their own family. It's kind of interesting to me that an entire order of mammals, lagomorphs, which I beforehand wouldn't have predicted, sort of merited as much of a category as, say, carnivores or insectivores, of which there are many more different types of different species.

So not nearly as much diversity within that order, only two different families. So we've covered basically all of the larger orders of placental mammals already. There are, perhaps, eight or so more, small ones, which I'll go through in much less detail, because there are only a handful of species in most of these. One species is called X, it starts with an X, I'm not really sure how to pronounce it, contains 29 species. This has antiters, tree sloths, and armadillos. And honestly, I'm not really sure why antieters aren't classified as insectivores.

I suppose there's a reason for that, but again, it's another example of a sort of non-intuitive distinction in classification. Then we start to get to quite small ones. There's an interesting mammal called the Pangolian, or Pangolan, which, and there's eight different species of this, it is the only known scaly mammal, so it looks a little bit like a reptile, but it is actually a mammal. It's got scales, though. It's quite interesting. Look it up. Eight species of those, they're in their own order, because they're quite distinct. then there is an order called Sirenia, four species of sea cows, a little bit like whales, but again different. Again, they're their own order. There are four species of hyrax, which is a small rodent-like animal that has its own order.

Elephants and mammoths have their own order, three different species. I believe there are two species of elephants, the African and the Indian elephants, and mammoths are extinct. I included them in there just because a mammoths are pretty cool. Anyway, two species of flying lemurs, and one species that's in an order all by itself, the Ardvark. That's special, the Ardvark, quite an unusual animal. Also, most well-known simply because of its place very early in the dictionary as it starts with two A's.

But it's also special because it has its own order in the placental mammal subclass. So that's basically all the mammals, except you might have noticed that I've missed out one very important order. In fact, one that I've been talking about almost constantly over the course of this series. That is the primates. I haven't actually talked in detail about the primates yet. I sort of skipped those because I deliberately wanted to finish on the primates, hopefully for obvious reasons. There are about 400 different species of primates, so they're one of the larger orders in placental mammals.

Remember the biggest ones, rodents with 2,300 species. bats with 1,100 species and insectivores with 540 species. But then just below that are the primates with about 400 species. So quite a lot of different types of primates. A very bit of diversity there. There are two main sub-orders within the order of primates. One has basically lemurs and other things that are like lemurs, including Lauricids and Gallagos and things like that.

There's about six or so families within that sub-order, over 110 species. So lemurs, sportive lemas, bush babies, dwarf and mouse lemas. I won't dwell on those because they're more distantly related to humans, but they have their own sub-order in about one quarter of all primates are lemurs of one sort or another. But then we move on to the other sub-order, which includes monkeys and apes, and also tasias. Tarsia's interesting animals. They're sort of like...

Well, they're a little bit like monkeys, but they're small, and they have very large eyes. They are nocturnal, hence the large eyes. They look slightly cute and slightly creepy at the same time. So just looking up a picture of them. But anyway, Tarsias have their own families, about ten species of those. And then the remaining eight families or so

within the suborder of Tarses, monkeys and apes, basically can be divided up into what I think of as sort of three, these aren't even really taxonomical groups, there's just sort of a, it's sort of a classical way of talking about, talking about some of the higher primates. There's the monkeys, the lesser apes, and the greater apes. And, of course, as you go along from monkeys to lesser to greater apes, that you get closer and closer to humans.

So that's perhaps a slightly useful way of thinking about it. There's also, there's Tarsias and marmosets, which are in their own family, so Tarsus, 10 species. Marmacets have about 42 different species. Mammasettes are essentially new world monkeys. So this harkens back to the distinction I was referring to before about the Old World versus New World example.

There's another family of monkeys with over 130 different species called Old World Monkeys. So these ones are the New World Monkeys, the Mammasettes. There's other families of monkeys as well. There's squirrel monkeys which have their own families, 17 species, 10 species of owl monkeys. 28 species of halar and spider monkeys. And there is also a family containing about 40 species of animals called the Titis, the Titus,

Sakis, Sakis, and another name that I can't even pronounce. These are other versions of New World monkeys essentially, monkeys found in the Americas. So in total, that's about what, six different families of monkeys. So quite a lot of diversity among monkeys. perhaps 200 or 250 different species in total and they form the majority of the diversity within the primate order, so different families of monkeys. When added to the tarses,

that leaves only 24 different species, 24 additional species, which include the lesser apes and the greater apes. The 17 species of lesser apes are gibbons. And gibbons look kind of a bit like chimpanzees, I guess. I mean, loosely you can sort of think of them as a cross between monkeys and chimpanzees. That's obviously not correct. They're gibbons, they're their own thing, but that's a little bit what they look like.

They're evolutionarily more distant from humans than the greater apes, but be closer than the monkeys. So 17 species of gibbons. We now move on to the so-called greater apes, so-called because they are larger and, I guess, supposedly more intelligent. than the so-called lesser apes or the gibbons. There are seven species of these. They're in the family called hominids. This consists of humans plus our closest relatives in the great apes and also a number of extinct species that I'll mention briefly later.

So seven species of great apes, the evolutionarily most distant of these from humans are the orangutang. These are found in Southeast Asia. There's two species of orangutan, Borneo and Sumatra, basically found in the islands of Borneo and Sumatra. respectively. Next closest related are the gorillas, two species of gorilla. Those are these are found in Africa. There are two species of chimpanzee which are also found in Africa, Central Africa particularly, the common chimpanzee and the bonobo, which is a fairly rare

form of the chimpanzee, but in the sense that their range is quite restricted. They're also much less sort of violent, much less aggressive than the common chimpanzee as far as I've been able to determine. Quite interesting how such too closely related species can be quite different behavior in many ways. And then, finally, we arrive at the genus Homo, which has only one species, Homo sapiens, and that is, of course, human beings. It literally means wise man, Homo sapiens. Although there is only one extant species in the Homo genus, there are a number of extinct species, which also are thought to be classified in the homogenus. These include species you may have heard of before including Homo Habilis, lived about 2 million years ago,

Homo erectus, a little bit more recently, Homo Neanderthalensis, that one's very controversial because Neanderthals, or Neanderthals, only died out a few tens of thousands of years ago. Some people think that, or some scientists think that they should actually be classified as a subspecies rather than a separate species. So they would prefer to say that there are, there's one species, Homo sapiens,

and then within that there is a subspecies homo sapiens, sapiens, which is modern humans, and then there's another subspecies homosapians, Neanderthalensis, which are Neanderthals, and there are perhaps even other subspecies that people are proposed. That's still quite controversial. At least for our purposes here, I think it's a bit simpler just to think of Neanderthals as being a separate species in the homogenus, because it's just a bit neater, but the final word is certainly not in on that, and I'll probably, at some point in the future do a podcast specifically on human evolution, because that is a very interesting and complicated topic. But there are certainly a number of other extinct species in the homogenes, including some of those

I mentioned. Homo gaster is another one, and there are quite a lot of them. More are being discovered all the time, really. And it's still a bit up in the air as to exactly how all that fits together. But certainly, only one species of human beings. I should mention that, briefly about race, different races of humans are not considered to be different species. There was some sort of debate about this in the late 19th century, early 20th century, but that's pretty much over. now. It's indisputable, biologically speaking, that all human beings are part of the same species.

One classic criteria for whether different animals are part of the same species, it's not perfect, but it's sort of pretty good, rough and ready measure, is whether they can interbreed, and all humans can interbreed with each other easily enough. Also, the genetic difference between humans in different so-called

races is quite low. In fact, there's more genetic diversity within races, say Africans or black people or whatever you want to call them, whatever one wants to refer to that so-called race as, there's more diversity within that group of people than there is between black people and all of the other alleged races. So races are not really used as a taxonomical concept at all.

Well, there is actually a taxa, sort of a name called race, but that doesn't really correspond to the same thing we think of as race. It's just a sort of a technical term. Also, along similar lines, the different varieties of cats and dogs and other domestic animals as well, even though they can look dramatically different, are all part of the same species as one species of domestic dog, one species of domestic cat. The different types are what are sometimes called breeds. I guess the key point to understand there is despite what seemed perhaps to us to be quite striking physical differences, perhaps in humans that skin color or the shape of the eye or other things like that,

And in the case of cats and dogs, it's in terms of the size and shape of tail and face and things like that. Despite those apparently very large or substantial physical differences, the actual underlying morphology, anatomy, behavior and so on, is very, very similar. In fact, so close that they are part of the same species. So just a brief note on that to clarify what, to some people, can be a little bit confusing. So let's finish off this series of episodes by just, starting at the top and going down the tree of life to outline how humans fit in at all. So at the very highest level, humans are eukaryotes.

That's the domain of life that we are in. That means that we have cells which have a nucleus and complicated intracellular organelles and more complicated DNA regulation and other things like that, distinct from bacteria and other types of prokaryotes. So humans are eukaryotes. That's the domain we're in. The next level down is kingdom. We're in the animal kingdom,

which means that we get our energy or sources of carbon from somewhere else, so we eat, basically, as opposed to photosynthesizing or eating dead things like fungi do. And we also move around. So a kingdom of animals. Within that, we are in the phyla, or phylum of chordates, chordata, which means we have a nother cord, more or less a backbone, not quite right. bit close enough. And that distinguishes us from some of the other phyluses, say, arthropons and mollusks and echinoderms, which I mentioned for, and also the different types of worms. Within the phylam of

chordates, we fit into the class of mammals or mammalia, which means that we give birth to live young and suckle our young and have fur. Actually, that's quite interesting, because humans are one of the few mammals which don't have very much fur, or really don't have any fur. We have a bit of, we have hair, but not fur in the same way as most other mammals. There are a few other example. The rhinoceros is one other example, and the elephant. I don't think it's actually known why humans don't have a fur in that way, but anyway, that's a bit of an aside. So in the class of mammals, within mammals, we fit in the order of primates, monkeys, chimpanzees. Within the order of primates, we are in the family of hominids, which is the great apes, chimpanzees, gorillas,

around tanks and humans, then we are in the genus Homo and the species Homo sapiens. So from the top, eukaryotes, eukaryotes, animals, chordates, mammals, primates, homo, homo sapiens. That's where we are. That's where we sit in relation to the one and a half or so million other species of animals that have been described, just one among very many of the twigs on the outer edge of the tree of life. More animal species are being discovered all the time, and our knowledge of how they are best classified and how they're related to each other will certainly continue to improve in coming decades,

particularly as methods in cladistics and phylogenetics and so on, become more widely adopted and better understood, and we gain more information about that. So, that's the end of our journey. That's all for this episode. Hopefully you didn't find it too sort of tedious or difficult to follow. If you enjoyed this episode and would like to support the podcast, I would really appreciate it if you would jump onto iTunes and give the podcast a favourable five-star review and or a original review.

That really helps to promote the show and to keep it up in the iTunes listing. So that's probably the single most thing, most useful thing you could do to help the show. Another thing you could do is jump onto Facebook and search for the Science of Everything podcast and like our Facebook page, which also helps to improve the, visibility of the show. I also post up visual material to accompany the show and occasional news updates and other things. So, uh, appreciate if you do that. I'll, particularly, I'll be posting some relevant links to more information about this episode, uh, where you can get material to, to look

at the, the, the tree. I'll probably post up my, uh, sort of PDF document that, that has a list of all of the taxa that I've been talking about, because it is a bit hard to see how it all fits together, just, just verbally, but hopefully you got the idea. Anyway, if you want to send me an email, just to talk about how you like the show, how you don't like the show, or what suggestions you have for future topics or anything else. My email address is Fods12 at gmail.com. That's F-O-D-S-1-2 at gmail.com. I always love to get feedback from listeners.

Thank you for listening and I'll talk to you next time.