Lesson video

This lesson is called Classification and Species and is from the module Species and classification; Differences between species.

Hi there.

My name's Mrs. McCready and I'm here to guide you through today's lesson.

In our lesson today, we're going to explain how organisms are classified into groups, and see what a species is.

Now, in our lesson today we're gonna come across a number of keywords.

They're shown up on the screen now, and you can pause the video to take notes of them if you wish to, but I will introduce them one by one as we come across them.

So in our lesson today, we're going to look at the differences between organisms, then we're going to look at classification, and then we're going to look at species and genus.

So are you ready? I am, and let's get going.

Before we begin, we need to understand that an organism is a living thing, and there are millions of different types of living organisms on Earth.

So how many can you spot in the picture? Maybe pause and have a look, a really detailed look and see what you can find.

So did you spot the ostrich, the giraffe, the oryx? That's the one with really big horns.

There are plenty of zebras to see and there's also wildebeest, and perhaps some plants in the background too.

So there's enormous variety between the different organisms on Earth.

For instance, some some organisms can walk on four legs and are covered in fur.

Others, make their own food, and others, need to digest other organisms in order to get their food.

So let's just quickly check our understanding.

A stick and a stick insect are different organisms. Is that true or false? Well, hopefully, you said that was true, but why did you say that? Justify your answer.

Well, hopefully, you said that a stick insect has legs for moving around to find food, but a stick is from a tree that has no legs and makes its own food.

Well done if you got that right.

So what I'd like you to do now is to have a think of all the different animals that you can think of, and what the differences are between them.

So think about physical differences such as what they're covered in, whether they're covered in fur, or feathers, or scales.

And also behavioural differences such as when they're active like at daytime, nighttime, at dusk, and dawn, what do you think? Is there anything else that you can think of and make a mind map and put down as many differences between animals as you can think of.

So pause a video, come back to me when you're ready.

So what did you say? Well, you might have added that physical differences might include things like having a backbone, or a shell, or a soft body.

Some animals live on land, others live in water.

Animals have different types of teeth.

Some have really sharp teeth.

, others have very flat, wide teeth for grinding and chewing.

And some animals have their eyes facing forwards, whereas others have their eyes on the side of their head, and some animals don't have eyes at all.

You might have mentioned something about the type of food that they eat.

Some animals are herbivores and only eat plants, others are carnivores, and only eat other animals.

And other animals eat lots of different things, are omnivores like us, we eat both plants and animals.

You might have mentioned the different number of legs that some animals have.

Some have 2, others have 4, 6, 8, some animals have none.

You might have talked about how they move.

Some animals walk and run, others leap, some crawl, some wiggle, some don't move very much at all, or move very slowly, or very quickly.

And then as far as behavioural differences are concerned, you might have said that some animals hibernate.

You might have said about some being predators rather than prey.

And you might have said that some animals migrate, fly long distances, or travel long distances from one place to another at different times of year.

And I'm sure you've come up with many, many other differences, but there are just a few ideas in case you got stuck, well done! So let's move on to our second part of the lesson about classification.

So we humans love sorting things into groups.

So you might have sorted your books into author, or title, or genre.

So sci-fi versus romance versus the non-fiction books that you've got, for instance.

You might have sorted your music into different categories as well, or your pens and your pencils.

Librarians classify books so that we can find them easily.

And biologists classify animals, and that process of sorting organisms into different groups is called classification.

So if you've sorted anything into different groups based on their features, you have classified them.

Now scientists classify organisms into different levels.

The kingdom, phylum class, order, family, genus, and species.

They're the different levels that we classify organisms into.

And at each level, organisms have a set of common features.

The higher up in that list we are, the more organisms there are, and the fewer features that they have in common.

So in the kingdom and the phylum, there are lots and lots of organisms, and they share some characteristics with each other, but not very many.

Whereas, the lower down in that list we go, we have fewer organisms, which share far more features with each other.

So the genus and the species have very few organisms in their categories, but the features that they share, that they have in common, there are many, many of them.

So let's have a look at an example.

Let's have a look at the animal kingdom, for instance.

So in the animal kingdom, we might include lion, tigers, domestic cats, and dogs, bears, rabbits, humans, fish, birds, and earthworms. So they're all animals.

If we go to the next level down the phylum, and look specifically at the vertebrate phylum, then we will include the lion, and the tiger, and the cat, dog, bear, rabbit, the human, the fish, and the bird, but not the earthworm because the earthworm does not have a backbone.

If we look again at the next level down, the class, and specifically look at mammals, then we will include the lion, and the tiger, the cat, the dog, the bear, the rabbit, and the human, but we won't include the fish or the bird because neither of those are mammals.

The next level down, if we look at the carnivores, then we will include the lion, the tiger, the cat, the dog, and the bear, but we will exclude the rabbit and the human because neither of those are carnivores.

The rabbit is a herbivore and humans are omnivores, that means we eat both plants and animals.

The next level down is the family.

So let's zone in on the Felidae family, and that will include the lion, the tiger, and the domestic cat, but not the dog, or the bear.

And the next level down is the genus Panthera.

So, maybe you are thinking panthers here, and maybe that gives you an idea of which organisms we will include in this genus.

Well, we'll include the lion and the tiger in the genus Panthera, but not the domestic cat.

And then the final level is the species, so let's look at Panthera leo, maybe Leo you've heard of in context of Leo the Lion, the constellation, or maybe in Disney films, things like that, and so Panthera leo will only include the lion and not the tiger.

So you can see as we go down this series of classification levels, we get fewer and fewer organisms,' with more and more similarities between them and fewer differences.

Now there are five kingdoms. These are very, very large groups of organisms. And the kingdoms that scientists classify organisms into include the animal kingdom, the plant kingdom, the fungi kingdom, the protists, and the bacteria.

So the organisms in each kingdom have very basic common features.

For instance, all plants can make their own food, but there are also very many differences in their features.

For instance, some plants are evergreen, they keep their leaves all year, whilst others are deciduous, they lose their leaves in autumn.

So there are basic similarities in each of the kingdoms, and many, many differences.

So let's have a look and just check our understanding.

Which of the statements best describes the organisms in the larger groups such as kingdoms? Is it that more organisms with many similarities in their features? Is it that there are more organisms with few similarities in their features? Is it that there are less organisms with many similarities in their features? Or is it that there are less organisms with fewer similarities in their features? Which option do you think is best describing organisms in the larger groups such as kingdoms? I'll give you five seconds to think about it.

So did you select option B? Well done if you did, that kingdoms have more organisms with fewer similarities in their features.

Once we've classified an organism into a kingdom, we can then subdivide them into phyla, so that's the plural for the word phylum, one phylum, many phyla.

And again, we are grouping organisms based on their features.

So for instance, in the animal kingdom, the phyla are vertebrates.

So vertebrates are animals with a backbone, including the bird and the fish in the picture, plus mammals, reptiles, and amphibians.

Whereas the other phylum is the invertebrates within the animal kingdom.

And invertebrates do not have a backbone and include insects such as the butterfly and the stick insect shown in the picture, plus worms, arachnids, so spiders, and mollusks like slugs, and snails.

So we have these two phyla within the animal kingdom, the vertebrates, and the invertebrates.

So let's quickly check our understanding.

Here's Katie, she is a marine biologist, and while she was down at the beach, she finds these animals, a fish, a jellyfish, a sea urchin, a seagull, and a starfish fish.

So how would she, a biologist, classify these animals into two phyla? Would she group them with similar features? Would she group them by similar habitat? Or would she group them by similar name? What do you think? I'll give you five seconds to think about it.

Okay, so did you select option A? That she would classify and biologists would classify these animals by similar features such as the backbone, so the fish and the bird versus non-vertebrates, so the jellyfish, the sea urchin, and the starfish.

Well done if you selected that option.

Once we've grouped organisms into their phylum, we can then subdivide them into their classes.

And these are again, general features, this time, it might be such as the number of legs that they have.

Now looking at the invertebrates, this time, we can group invertebrate animals into the following classes.

So firstly, we can have a look at the arthropods.

These are the ones you are probably most familiar with, and include things like insects, spiders, millipedes, and butterflies, those sorts of things.

So animals with legs, jointed legs.

There's also the class of molluscs, so slugs and snails for instance, and annelid worms, so earthworms are included in the annelid worms. And there's also coelenterate, such as jellyfish.

There's also flatworms like tapeworm, and echinoderms, including starfish.

So these are the classes of invertebrate animals.

And you can see that there's actually quite a lot of differences between them, it's relatively easy to put animals, invertebrate animals into these various different classes because they are really quite different from each other.

Now we can classify ourselves because we are animals.

And so how are humans classified? Well, firstly, we're in the kingdom animal and in the vertebrate phylum because we have a backbone.

Then in the class, we are a mammal, and we are in the order primates, we are in the family of great apes called hominids.

And our genus is Homo, meaning human.

And finally, our species is sapiens, meaning wise.

So we are a vertebrate animal, in the class of mammal, the order primates, in the family of the great apes, and we are homo sapiens, that's our classification.

So let's have a look at classifying other organisms. So there's a chart there on your screen, and it includes groups and subgroups.

So which of these statements are true? Are all animals vertebrates? Are all insects invertebrates? Are jellyfish a type of fish? And do fish have more in common with birds than starfish? So which of these statements are true? I'll give you a few seconds to think about it.

Well, let's look at these options one by one, All animals are vertebrates, well, that's obviously not true because there's a group of vertebrates and a group of invertebrates Are all insects invertebrates? Well, the insects are in the class arthropods, which are in the invertebrates phylum.

So yes, that is true.

Are jellyfish are type of fish? Well, jellyfish are in the invertebrates section, and fish are in the vertebrate section, so that's not right.

And do fish have more in common with birds than starfish? Well, fish and birds are both vertebrates, and starfish are in the invertebrate section, so that is true as well.

Did you spot that? Did you reason that out, and use logic to work it out? Well done if you did, rather than just guessing, because that's really important that you can apply logic to questions like this so that when you come across other new scenarios, you can do the same.

So what I'd like you to do now is to have a look at the different organisms here, the fish, the fly, frog, the grass snake, slug, snail, and spider.

And if you can work with a partner, discuss and sort these organisms into groups.

So have a think, how many groups will you sort the organisms into? What rules are you applying to classify these organisms into their groups? And can you add the labels once you've sorted them of kingdom, phylum, and class to the groups that you've decided? So stop and really think about this.

Spend quite an amount of time on this to really think it through, make sure that your logic works sensibly, and come back to me when you're ready.

Okay, so how did you classify these organisms? Well, you might have sorted them such as this.

Well, you might have firstly said that they're all animals.

And then you might have grouped them into vertebrates and invertebrates.

And then you might have within the vertebrates, included the fish in the fish, and the grass snake in the reptile section.

And you might have included the frog within the amphibians.

And then in the invertebrate section, you might have included the fly and the spider in the arthropods because they've both got jointed legs, and you might've included the slug and the snail in the mollusc section because they're quite similar too.

So you might've sorted things in slightly different order, but hopefully, you've been able to apply the kingdom to the animal section, the animal layer, and then the phylum to the vertebrates in the invertebrates section, and then the class to the next level down.

Something a bit like that.

So just review your work, and see how your classification has compared to mine.

Okay, let's move on to our last section now, about genus and species.

So we've seen that as we move down through the classification system, we can group and describe organisms in much greater detail.

And when we get to the very bottom, we have the genus, which is very similar organisms, all grouped up together.

For instance, all bears have the genus "Ursus," and then the layer next to that, the next layer down the species, we see that there are very clear distinctions that polar bears are a different species, for instance, from brown bears.

So they're both in the genus "Ursus", but they're different species.

So what is a species then? Well, a species is a group of organisms with very similar features that can reproduce with each other to produce fertile offspring.

That means offspring that can then go and reproduce themselves.

So for example, two horses are of the same species, they can reproduce to produce fertile horses, so their babies can then grow up and have babies of their own.

Similarly, two donkeys can be produced to produce fertile donkeys, so again, their offspring can then have more offspring.

And so donkeys are in their own species as well.

But if you try and cross a horse with a donkey, you'll get a mule, and a mule is infertile.

If you want another mule, you can't cross a breed, reproduce a mule with a mule, and get another mule because that's not possible, mules are infertile.

So if you want another mule, you'll need to take a horse and a donkey, and breed those together to create another mule.

Now mules are really useful 'cause they're very strong, they've got the power of a horse and the stamina of a donkey, but you can only get a mule if you cross-breed a horse with a donkey because a horse is a different species from a donkey.

So let's have a look at this example then.

If a dog and a wolf are bred together, they produce fertile puppies, therefore the dog and the wolf are the same species.

Is that true or false, what do you think? So you should have said that that is true.

A dog and a wolf are the same species.

But why, can you justify your answer? Okay, well hopefully, you've justified your answer with the first reason, that organisms of the same species can reproduce to produce fertile offspring.

That's quite interesting, isn't it? Okay, so we've got organisms, which are of a genus and a species.

And together, the genus and the species is a binomial name.

So this is like a first name and a surname that we give to every organism, every organism has a binomial name made of the genus and the species.

So for instance, the red admiral butterfly has a binomial name of Vanessa atalanta.

It's quite pretty, isn't it? The wild daffodil that you will have seen around in springtime, Its binomial name is Narcissus pseudonarcissus.

And the fly agaric fungus, which you might have seen around in Woodland, its binomial name is Amanita muscaria.

So all organisms have a binomial name.

Humans is Homo sapiens.

And the binomial name is really important, every organism has one, but it also has some very specific formatting conventions that go with it.

So let's consider the Crocodylus niloticus, as an example, the Nile crocodile.

So if we look at the way it's written out, we can see that the genus name has the first letter capitalised, but all the other letters are lowercase, whereas the species name, niloticus is all in lowercase, and the whole thing is in italics or it could be underlined.

So these are the formatting conventions for writing out genus and species names, that the genus name has its first letter capitalised, and everything else is lowercase, and the species name is all in lowercase.

And then both the genus and the species name are either italicised or underlined.

So let's see some wrong examples.

See if you can spot the errors.

So the English Oak: quercus Robur, how is that wrong? How has that been written out wrongly.

So did you spot the q? That should have been a capital Q rather than a lowercase, and the R, that should be lowercase rather than capitalised.

And what about the Common Blackbird: Turdus Merula, what's the mistake there then? Yes, that's right, the lowercase M, that's what it should be, but it's been put as a capital letter instead.

Okay, so what's the correct example of the binomial name for the domestic cat, Felis catus, so which example is right? Have a look and see if you can spot it.

I'll give you five seconds.

So remember, a binomial name if it's correctly formatted, has a capital letter for the genus name, and the species name is all in lowercase, and it's either italicised or underlined.

And the only example there, which fulfils all of those requirements is the last one, with a capital F and a lowercase c, and that one in this case is underlined.

So well done if you spotted that, good eyes.

So what I'd like you to do now is to consider the case of the polar bear, Ursus maritimus, and the brown bear Ursus arctos, now these are bears, so they're related, but they are different species.

So take the table and complete it, fill in the gaps you've got all the information that you need there, so see what you can do with that.

Take your time, make sure you pay real close attention to it, and come back to me when you're ready.

Right, let's check our work.

So did you put the polar bear and the brown bear, both in the kingdom animal? And the vertebrate level is the phylum.

Now if the polar bear is a mammal, then so is the brown bear.

And if the brown bear is the carnivore, so is the polar bear.

And if the polar bear is in the family ursidae, then so is the brown bear.

Now the next level down is the genus, and the brown bear is in the genus Ursus, and we can see that the polar bear is also from the genus Ursus, we can see that from the name that it's been given to the side, or also, the fact that they are both bears as well.

But the differences are at the species level.

So the polar bear, its species name is maritimus, whereas the brown bear, its species name is arctos.

So did you get all 10 of those right? Well done if you did.

Okay, well I hope you've enjoyed today's lesson, I really have done.

And just to review what we've learned today, we've seen that in classification, the similarities and differences in organisms features are used to classify organisms. And that we classify organisms from kingdoms at the top, all the way down to species at the bottom.

And that in that top level, in those top levels such as kingdoms and phyla, there are more organisms with fewer similarities.

Whereas at the bottom, there are fewer organisms with more similarities.

And every organism has a binomial name, which gives it its genus and its species.

And we know that a species is a group of organisms, which can reproduce with each other to produce fertile offspring.

So I hope you've had a great lesson, I have.

It's been lovely having you to join me, and I hope to see you again soon, bye!.