Hi. It's Mr. Andersen. And in this podcast I'm going to talk about the animals.
We're going to talk about kingdom animalia. And all of these thing are animals. Sometimes
we refer to them as just, if we say animals, were talking about vertebrates, but this little
water bear, insects and all these things are going to be animals. And you are an animal
as well. If we look at the phylogeny of animals, these are eukaryotes. So we're looking at
things that have a nucleus and organelles. We're going to be right here. Metazoa is the
group that we're in. Who are some things that you might even know around us? Fungi are going
to be relatively close. Or the amoebas are going to be relatively close. But we're pretty
distant from green plants. If we look more detailed and the metazoas, basically this
is our phylogenetic tree. It goes all the way from things like jellyfish down here up
to spiders here. And so we have a lot of different types of animals. But we don't have to learn
all of those. In other words in my class we're going to learn these invertebrates. And we're
going to learn these vertebrates. So these are going to be things that have a spinal
cord. And these are things that don't. And we'll get to those in just a second and how
they're classified. But before we get to that, let's talk about some of the characteristics
of animals. Well we already said that they're eukaryotic. So they have a nuclei. All of
these are going to be multicellular. And they're motile. In other words they move around. Or
they have stages in their life when they're going to move. The opposite of motile is sessile.
And so all of these are going to be moveable. And then they're heterotrophs. In other words
they have to eat their food. And so there's a lot of things I just said. So basically
what are animals? They're multicellular, moveable heterotrophs. And if you can think of that,
then you're pretty good on definition for animals. They don't have a cell wall. And
in general they'll go through a blastula at some point in their development. But we've
got a lot of things that fill that role. So this would be a flat worm and an insect. And
some things that you don't even think of. So sponges for example are going to be animals
as well. So when did the animals show up? Well they showed up 530 million years ago
during a time that we call the Cambrian Explosion. And the reason we call it an explosion is
we if look in the rock layers in Canada, like the Burgess Shale, if we look in China or
Greenland, what we find is at this one level we find this explosion of all these different
types of animals. They see segmentation. And then they just take off. This would be an
example of one of those organisms from the Cambrian Explosion in this primitive sea.
And the cool thing about the Cambrian Explosion is all the organisms we have today can trace
their ancestry right back to this one point. And so it shows the animal group is monophyletic.
So basically I'm going to walk you through how we classify the invertebrates. These are
things that don't have a vertebral column or don't have a spinal cord is the best way
to think about it. And so the first thing that we do is we separate into those that
have just bag of tissues and those that have true tissues. And so those that have a bag
of tissues are what are called sponges. So sponges are just an amalgam of a bunch of
different cells. I've heard that you can actually pass a net through a sponge. It will actually
form on the other side. And so we group that as our first classification group. Next way
we divide them is based on their symmetry. Symmetry is basically how you look right to
left or front to back. And so the two different types we have are what are called radial symmetry.
So this would be an organism that no matter which way you cut it, they're going to have
radial symmetry. Now we don't show that. In us we're going to show what's called bilateral
symmetry. And that basically means you that can't just cut us either which way. There's
going to be a clear right side and a left side. And so this would be an organism that
show bilateral. And this is radial symmetry. An example of things that show radial symmetry
would be the cnidarians. And so these are going to be things like jellyfish. And also
the sea anemone. So basically a jellyfish is like this and an anemone is like that.
Next the way we group them is whether or not they're protostomes or deuterostomes. So basically
how does life form? You have a zygote. That zygote is undergoing cleavage. And it's eventually
remember going to form a blastula. That blastula is simply a sphere of cells. And that eventually
is going to fold in on one side. And it's going to form a gastrula. And so basically
that gastrula is going to fold in on itself like that. And that's called gastrulation.
And so that hole, that initial hole can form a mouth. And it forms a mouth and then you
are protostome. Or it could form an anus. And if that first hole forms an anus then
you are a deuterostome. So sadly we are deuterostomes. That means this hole formed an anus. And that's
where we are. The other only deuterostomes are going to be the echinoderms. Things like
this sea star right here. If we breakdown the protostomes, protostomes are going to
be broken into two groups, acoelomates and the coelomates. So basically when you get
this folding in where you have a endoderm on the inside, mesoderm and then ectoderm
on the outside, sometimes we'll get a little coelom or a gap inside there or a space. Those
that don't have that are called an acoelomates. So an example would be flatworms, like a planaria.
And then those that have coelomates are broken further down into what are called pseudocoelomates,
those that have a coelom, but it's not really surrounded by mesoderm. And then the other
ones. So the other big groups are going to be the annelids, which are going to be the
segmented worms like the leaches. The arthropods, those are going to be the segments as well.
Those are going to be things like insects and crustaceans. And then finally we have
this group which are going to be the molluscs. And so if I were to classify humans, where
are we? We're going to branch off this and we're going to go to the next page which is
going to be the chordates. But these are the invertebrates that you should know. From sponges,
which is going to be these. They live in the ocean. Basically they're going to take in
sea water and they're going to grab material out of it. The Cnidarinas. A lot of these
are predatory. The flatworms like the planaria is an example of that. But we also have these
really gorgeous flatworms that are going to be found in the ocean. Molluscs are going
to be things that have a foot. And so those are going to be things, for example would
be this clam right here. But it's also going to be things like a snail. And it even goes
all the way up to squid and octopus are going to be part of the molluscs. We then have the
annelids which are going to be the segmented worms. The arthropods. Again like I mentioned
are the insects, spiders would be found in here. The nematodes are going to be the round
worms. And then the echinoderms which are going to be the sea stars. We would also put
sea urchins in here as well. So those are the big groups of invertebrates. If we talk
about the vertebrates, well the vertebrates, the big ones you should know if we go all
the way here would be some things that you're not familiar with like the lancelets down
to the lampreys. The cartilage fish, chondrichthyes, are going to be things like sharks, skates,
rays. We then have the bony fish. The lobe-finned fish, which we though most of them were extinct
until we found the coelacanth. The amphibians, the reptiles, the mammals. We put things like
dinosaurs and birds in this group right here. But there are going to be defining characteristics
of each of these. In other words what separates a lancelet from everything else? Well they
actually have a head as we move down here. Or if we go to the cartilage fish, they're
going to have a jaw, but the lamprey is going to be a jawless fish. So they don't have that.
We're going to get to lungs or lung derivatives or things that come from that. And so these
are characteristics that are found all the way down. So what separates mammals from reptiles
is the ability to produce milk. Now these are simply derived characteristics that are
found in this group. Remember this isn't how we classify life anymore. The way we classify
life is generally using DNA. And we're figuring out who is related to whom based on that analyzing
DNA. Figuring out similarities and then basing it that way. But this is the group of vertebrates
that you should be familiar with. There's way more than this, but it's a great start.
That's animals. And I hope that's helpful.