Lesson video

Hi, everybody.

It's Miss Simkin back again for your next science lesson.

I hope that you are having a lovely day so far, and I think let's just get started today on our lesson.

So our lesson question today is what adaptations do nocturnal animals have? So, so far we've looked at the adaptations of animals that live in cold environments and hot environments.

And now we're going to have a look at animals that live in nighttime environment, so they are active during the night, that's what it means to be nocturnal.

We'll talk more about that in a second.

Before we begin could you please make sure that you have these things, piece of paper, a pencil, a colouring pencil, and a ruler.

If you don't have these things just pause the video for me, and go and get them now, please.

Fantastic.

Let's start with our star words.

This is the key vocabulary that we're going to need today.

So we're going to practise saying it.

I'm going to say it and point to myself, and then you're going to say it when I point to the screen.

Adaptation, echolocation, pupil, camouflage, nocturnal, diurnal.

Well done.

Okay.

So we're going to talk about what those words mean before we start.

And some of them we have covered before in this topic.

So an adaptation is a part of an animal's body, or the way it acts that helps it to survive.

Camouflage an example of an adaptation, camouflage is when an organism blends in with its surroundings, so it's the same colour.

Echolocation is also an adaptation.

I'm actually going to save that meaning for the end of the lesson when I explain what echolocation is.

Nocturnal is our main focus for this lesson.

If an animal is nocturnal it means it's mostly active at night.

And then the opposite of nocturnal is diurnal.

So that's when an animal or an organism is mostly active during the day, so they're the opposite.

So humans were diagonal, we're mostly active during the day.

And then our last word is pupil, now this has two meanings.

Pupil can mean someone who's studying at school like you, or at home like you, but that's not what I mean today.

I mean pupil as in the part of our eye.

So if you've learned about the eye before, or maybe you've watched our other lessons on Oak National about light, then you'll know that the pupil is the black bit in your eye, the black circle.

When we get back to that part of the lesson we'll talk about it in a bit more detail.

This is what we're going to learn today.

We're going to start with our recap, we're going to look at the benefits of being nocturnal, why you might want to be nocturnal if you're an animal.

We're going to look at the differences between night and day.

We're going to look specifically at the eyes of nocturnal animals.

And then we're going to learn about echolocation which is one of my favourite science topics, I love echolocation.

So let's start with our recap.

What can you remember from our previous lessons? Here is a picture of a cactus.

Can you remember any of its adaptations that it has to help it survive? If you can pause the video and write them down now.

Great.

So well done if you remembered any of these.

A cactus has waxy skin to stop water loss.

It has spines to stop things from eating it, and also to prevent water loss.

It's got water storage inside, it's big, succulent juicy stems. And those read long roots you can see are called tap groups, and they can be 7 to 10 metres long, and that's to help the cactus to find water from far away.

Well done if you remembered those.

Again next bit of recap now that our memories are warmed up I'm going to give you three animals.

You can see here we've got an emperor penguin, a polar bear and reindeer.

These little animals we looked at in our lesson.

Can you remember any of the adaptations of these animals to live in their cold environments? Pause the video and see what you can remember.

And you don't need to write down every single adaptation.

Maybe give yourself there two seconds, and see what you can come up with.

Pause the video and do that for me now, please.

Great.

Okay, you could have written lots of things for this, camouflage is one, they're all camouflage to their environment, they all have thick fur or feathers, they all have thick layers of fat for installations.

We spoke about that last lesson, installation is what stops heat from escaping from your body.

The reindeer migrates, so it travels really long distances, they've all got claws so that they can walk easily through snow and ice without slipping and sliding everywhere.

There were lots of other things you could have written as well.

So good job if you remember any of those.

Now we're going to move to today's lesson focus, and that's the benefits of being nocturnal.

So we've spoken about it already.

If you're a nocturnal animal it means that you are mostly active at night.

So we've actually learned about animals that are nocturnal already in this unit.

So being nocturnal is an adaptation that helps an animal to survive.

So for example the kangaroo rat that we learned about when we looked at desert environments, one of its adaptations for being able to survive in a desert is that it's nocturnal.

So it's mostly active at night when it's colder in the desert, so that helps it to survive in those really hot temperatures.

It basically just avoids them in the day.

Can you think of any other reasons that an animal might be nocturnal? That's what we're going to look at next.

So here's an example of another animal that's nocturnal it's a bat, and I'm going to show you some more animals that are nocturnal in a second.

So bats don't live in the desert so what reason might a bat have for being nocturnal? So there are a couple main reasons, like our kangaroo rat it might be to avoid extreme temperatures.

Another reason that being nocturnal is an advantage is that it's much harder to be seen at night.

So if you are our bat on the previous side, and you're flying around at night, this is really helpful that it's hard to see you for two reasons.

The first is that you're less likely to be detected by your prey.

So if you're a bat and you're flying around at night trying to catch flies and moths, they're much less likely to see you coming which is really helpful, it means you're more likely to catch them.

It also helps you to avoid predators because again if you are harder to see then predators are going to be struggling to catch you.

So two good reasons, you can catch your praying more easily, and it's easier for you to hide from your own predators.

And the last reason is that there's less competition.

So let me explain what I mean by that.

Imagine you are an animal who is living in a desert, or in a Savannah where there's limited water, and there's one big watering hole or one oasis where lots of animals are going to get their water.

During the daytime this is going to be really busy, and it's going to be quite hard for you to compete to get that space and to get that water, that resource you need.

Whereas at the nighttime things are much quieter.

There's less competition at that watering hole.

So that is one of the benefits of being nocturnal, okay.

The water's just an example of a resource there but the same could be said for food, fruit trees that animals that are eating from, and so on, or and so on.

Here now are some examples of nocturnal animals that live in the UK.

So we've got badgers are nocturnal, bats are nocturnal, we've got a few species of bats here in the UK.

Owls, all sorts of species of owls, this one is a barn owl.

Hedgehogs, and Foxes.

And then here are some examples of animals that are nocturnal that don't live in the UK.

So this is a sugar glider, it's very sweet looking.

This is a scorpion, much less sweet looking.

I'm quite glad that they're active at night, and not active during the day.

And a honey badger, this is a very aggressive animal that actually can fight snakes in the Savannah.

So if you have never watched a video of a honey badger fighting a snake, I would suggest as some extra work at the end of the lesson you go and have a look.

And this very funny looking creature is called an aye-aye, so as well as looking funny, it's got a funny name, and this is actually a very peculiar kind of lemur that lives in Madagascar.

So all of these animals are nocturnal.

Do you notice anything that's similar about all of these animals? One of the things you might have noticed is that they are all a dark colour.

The majority of their body is covered in either a dark casing like the scorpion or dark fur.

Why do you think that might be? It's to help them camouflage, great.

Because they're nocturnal they're active at night when it's dark.

So if they're dark coloured they're going to blend in, they're going to camouflage much more easily.

I've got some questions for you to answer now, please.

Your questions are, what does nocturnal mean? What are some of the benefits of being nocturnal? And can you name three nocturnal animals? You can name more if you like but at least three, please.

Pause the video and complete those questions for me now.

Fantastic.

These are your answers.

Let's mark them together.

Give yourself a tip if you've got them correct.

Or if you made a mistake that's not a problem at all just underline it and write in the correct answer for me please.

So number one, nocturnal means mostly active at night.

That mostly part is quite important because it doesn't mean that we're never going to see a nocturnal animal active during the day, it just means that they do most of their activity at night time.

The same way as a diurnal animal like us we're mostly active during the day but it doesn't mean we're not sometimes up and active at night, okay? Number two, animals that are nocturnal, let me try that again, animals that are nocturnal can avoid hot day time temperatures, so that's one reason you might have written, avoid being detected by their prey or predators, and they have less competition for resources.

And number three you could have had any of the examples we went through, so owls, hedgehog, badger, bat, fox, scorpion, aye-aye, sugar glider, honey badger.

You might have had something different, if you have some good animal knowledge, and you know of a different nocturnal animals as well.

If you need some time to correct your answers just pause the video for me to do that now.

Brilliant.

Next we're going to look at night and day in a bit more detail.

We're going to think about night and day almost as an environment, and think about what conditions are different in the night and in the day.

So here is an example of a nighttime environment, and the daytime environment.

What is the main difference between these two environments? If you know it write it down, point it to your screen, say it.

Is the amount of lights, okay? So in our nighttime environment it is very dark.

There's a small amount of light coming from starlight, or light from the moon.

So the moon appears light cause it's reflecting light from the sun, but still that provides some light, but mostly it's very dark.

Whereas in the day we're getting lots of light from the sun even from a cloudy day the sunlight is still getting through.

So that's the main difference.

So as well as being an adaptation itself, so being nocturnal is an adaptation to living in a hot environment for example, there's also another set of adaptations that come along with animals that are nocturnal.

Because if you are mostly active during the night then there are certain things like it being really dark that you need to be adapted to survive.

So, quick recap of our five senses.

They're sight, hearing, smell, taste, and touch.

Which of these five senses would be effected during the night? Which one is going to have to work harder than normal, or it's not going to be very useful? It's site.

So because it's mostly dark at night it is hard for diurnal animals like us to see.

So nocturnal animals have different adaptations to allow them to see or to move around, and make sense of their environments during the nighttime.

So it might be that their sense of sight is much stronger than ours, or other diurnal animals.

Okay, so that's one way that they're adopted.

They compensate, they have a better eyesight than we do, and we're going to learn about that in the next section.

The other way that they might compensate for this lack of light is that there other types of senses.

So their hearing, their smell, their tastes, or their touch might be heightened.

This means their better.

So as well as having better eyesight than us, some nocturnal animals have better hearing, or better smell, or better taste, or better touch.

So some examples of this are snakes who are often active at night.

They don't have particularly good eyesight but they do have a really good sense of taste.

So they use their tongue to taste the air which is quite impressive.

They also have really good sense of touch because they can sense heat.

So without even touching another animal they have like thermal senses, they can just sense the body heat of an animal that's close to them.

I don't know about you but I can't do that.

If there was somebody sat next to me here I'll be able to see them.

But if my eyes were closed I wouldn't be able to feel their body heat whereas snakes can.

Some nocturnal like cats have really good sense of hearing.

Not only is their hearing better than ours they can also move their ears, I don't know if you have a cat at home if you've ever seen it do that, where they can make twitch their ears towards the direction of sound, that helps them to hear, so that's an adaptation to help them at night time.

And lots of nocturnal animals have a really good sense of taste, sorry, really good sense of smell.

And because of this they can communicate with each other with smell.

So if it's hard to see the animals around you, or to like see their tracks to figure out where they've gone, then one way around that is scent marking.

So nocturnal animals like a badger for example, they leave their scent behind.

So they'll spray it or they'll rub it.

And that means other badgers that are looking for them can come up to maybe that tree where they've said scent marked, sniff it, and go, oh, that's most like Fred, Fred rusted from here, okay.

So scent marking is another adaptation to being a nocturnal animal.

Here are your questions for this section.

Can you describe one example of an animal with heightened senses? So we just spoke through a couple of examples there.

I gave you three animals and four examples.

Can you remember one of them? And pause the video piece and write it down.

Great.

Let's mark our answers.

So you could have written any of these examples, or again if you have really good animal knowledge you might have written one of your own.

So some snakes are able to taste the air with their tongues.

Cats are able to move that ears towards different sounds.

Some snakes are able to sense heat.

And badgers and lots of other animals who are nocturnal can scent mark to communicate through smell.

Well done if you've got any of those.

And if you want to challenge yourself you might want to pause the video now, and write down a few more of these options.

Great, let's move on to looking at the eyes of nocturnal animals.

So before we begin let's just recap how we see.

So this is a zoomed in picture of a human eye.

So let's talk about how humans see because it's pretty much the same for most other animals.

So we see when light bounces off an object, and into our eyes.

It enters our eyes through something called the pupil, which is that black circle on the eye that you can see, and on your eyes as well, so that's the pupils.

So that's actually a hole through which light can enter.

It's then focused by the eye, it's collected at the back of your eye, and a signal is sent to your brain.

It's much harder to see especially for humans, and diurnal animals during the nighttime because there's not enough light entering our pupils.

But let's learn now how nocturnal animals get around this because lots of them can see really well at night.

So the first thing is the size of their eyes.

So this is a picture of an elephant as I'm sure you are aware, which is a diurnal animal, an animal that's active during the day.

Have a look at the size of its eye.

Have a look at the size of its eye in relation to its face.

If you were to put it as a fraction, I mean, it takes up a tiny amount of that space, maybe like one-fiftieth.

Now if we compare it to our lovely sugar glider from before, look at the size of the sugar glider's eyes, and look at it in comparison to its face, its eyes take up a quarter of its face.

They're really big, and that's actually why it looks so cute, we often find things with bigger eyes cuter.

Okay, so that's one of the differences between the eyes of diurnal and nocturnal animals.

Nocturnal animals have bigger eyes that allows more light to enter their eyes, and it also means their eyes are more sensitive.

Here's another animal, this one's diurnal, so lions are mostly active during the day, and that's compare it this time to another nocturnal animal, an owl.

So here you can see the owl's eyes are a bit bigger, but can you see another difference between their eyes? I'm going to give you a hint, it's one of our star words today.

Yeah, so if you have a look here the pupils are both different sizes.

So not only are eyes generally bigger in nocturnal animals, but their pupils are much bigger as well.

So you can see on the lion it's a small circle, on our owl it's a big circle.

And remember I told you that pupils are where the light enters, so if our pupils are bigger then they can let much more light in, okay.

So that's another adaptation that lets nocturnal animals see in the nighttime.

Okay, the last one I'm going to show you is another interesting thing about the eyes of lots of nocturnal animals.

So this is a cat which is a nocturnal animal, and you can see here that its pupils, sorry, are really, really big.

However, what that means is that cats can see really well at night time because that lots of light is coming in.

But during the daytime they have to be careful not to let too much light in because their eyes are much more sensitive.

So if you have ever looked directly into the sunlight which I hope you haven't 'cause it's not very safe, but you'll know that feeling of like, oh, it's too bright, I have to close my eyes.

There's such a thing as too much light coming into our eyes, and because nocturnal animals have really sensitive eyes, and they're adapted for the nighttime, it means that they have to be careful with normal amounts of light during the day, which is why cats have pupils that can turn into slits during the day.

So at night or when they're hunting like that cat in this picture, they're really big and brown to let lots of light in.

But during the day they're really thin slits, okay, this is different.

My eyes never turn into slits and nor do yours.

So this is an adaptation that cats have because they're much more sensitive to the light than we are.

And if their pupils are slits, then it stops too much light from coming into their eyes.

So if you have a cat at home have a look at its pupils, and see when they are slits, and when they're big and round.

I would like you pleased now to answer this question, describe the differences between the eyes of nocturnal, and diurnal animals.

And I have a sentence stem below for you to follow.

Now, we've spoken about three differences.

So you can either choose one to focus on, or you can put all three into your answer.

So bigger eyes, bigger pupils, and pupils that can turn to slits during the day.

And this is the sentence stem I'd like you to use, nocturnal animals have.

In contrast, diurnal animals have.

This is because.

Pause the video and complete that for me now, please.

Fantastic.

Let's check your answers.

So, we might have all written slightly different answers to this.

So don't worry, yours doesn't have to be exactly the same as mine, but here is an example, nocturnal animals have bigger eyes and bigger pupils.

In contrast, diurnal animals have relatively smaller eyes and pupils.

This is because nocturnal animals are mostly active at night when there is much less light, and so they need bigger eyes and pupils to let more light into their eyes.

This is an opportunity now for you to give yourself a tick if you feel like you covered all the points, or to pause the video and see if you can edit your answer, and make it even better using the example that I have on the board.

Pause the video and do that for me now, please.

Fantastic.

Okay, well done.

You're working really hard.

We've learned lots already this lesson.

We're going to learn about one more adaptation, we're going to learn about echolocation which is actually all to do a sound.

So we're moving away from our adaptations that are relevant to light, and we're moving into an adaptation that is all about sound.

So, this is just a picture of a speaker, and it's showing us that sounds a created when an object vibrates.

So when a speaker vibrates, and if you've ever put your hand next to a speaker then you can feel it vibrate very slowly, sounds travel in waves from an object, okay? So if you've learned about sound before then you will know that, but it's something important to understand what we're going to learn next.

So sounds travel in waves from an object.

So you can see our green sound waves moving from our speaker here.

Sometimes sounds might create an echo, and that's when the sound has bounced back 'cause it's reflected from a surface.

So this is an example of what an echo would look like if we were to draw it.

So sound coming out on a speaker, and then dancing back and creating an echo.

And if you've ever been in a cave, and you've heard an echo, echo, echo, echo, that's what it sounds like.

That's the sound bouncing off the reflected surface, okay, so that's important.

We know that sound waves travel from an object, and they're are caused by vibrations, and if they reflect back off an object they can cause an echo.

Now, bats that's an example of a nocturnal animal that use those properties of sound to their advantage.

So bats are nocturnal animals that don't have very good eyesight.

So that means they're going to have to rely on their other senses.

And bats use something called echolocation, which uses sound waves to help them kind of see in the dark.

So bats can produce a little light chirping clicking sound that sounds like, , something like that, a bit more high pitched than I'm doing, and they sent that signal out, and they see if an echo returns to them, or they hear for an echo to return.

And by waiting for that echo they can figure out what's in front of them.

So if I just give you a really simple example of this.

Imagine that I'm standing in a dark room, or I have my eyes closed, so I can't see anything.

And there's a wall in front of me, and there's one gap in that wall that I could walk through.

If I walk forward anywhere else I'm going to walk, bang into the wall.

But there's one space where there is a gap that I could walk through without getting hit, without walking into a wall.

During the daytime or when the lights are on that would be fine.

I would just use my eyes, I would see where the gap is and I'd walk through it.

At night time would be much trickier for me because I wouldn't be able to see the wall or the gap.

Now the way echolocation works is kind of like if I was in that room and I have a tennis ball in my hand, now what would happen if I threw the tennis ball at the wall? It would bounce back to me.

What would happen if I threw the tennis ball, and it went through the gap so there was no wall there, it was where the door opening was? It wouldn't bounce back to me.

So what I could do is I could stand in that room, and I could throw the tennis ball and catch it every time it came back to me.

And then the time that it didn't come back to me I would know that that's where the gap is, and I can walk through it.

And that's kind of what are doing with echolocation.

They're throwing sound out, and if it comes back to them then they know that there's something in front of them.

So I'm going to explain that now I'm using a diagram.

So here is a picture of a bat that's flying around in the nighttime trying to catch its prey.

It sends this chirp, these echolocation sound waves out, okay? And if there's nothing in front of it then they're just going to keep going, and the bat will know to keep flying in that direction, or that none of its prey is there.

However if a moth or a butterfly, an example of something that a bat would eat is in front of the bat then those sound waves are going to bounce back as an echo like that, okay? And when those sound waves bounce back as an echo the bat can then process those sounds, and it sends a signal to its brain saying that something is in front of it, that there's a butterfly there.

Now this sense in bats is so heightened and so sensitive that it's much more sensitive than me throwing a ball at something.

It doesn't just tell the bats, oh, there's something in front of you, or there's something not in front of you.

It actually tells them the size and the shape of the object, so it's very, very impressive.

So this adaptation is called echolocation because it uses echoes, so that bouncing back off sound to help the bats to locate objects, okay.

So I'm going to go through that one more time, and then I'm going to ask you to draw a picture like this yourself so following really carefully this time.

So, a bat sends sound waves out.

If there is an object in the way of those sound waves then the sound waves will bounce back towards the bat like an echo.

The bat can then hear those sounds and process them, and create an image in its brain of what is in front of it, and that's how echolocation works.

Can you have a go please at drawing your own diagrams? So draw a bat and it's preying, an outline is fine.

And then I'd like you to draw a diagram showing the steps I've just taken you through.

So sound waves, I would suggest using maybe a colour, you might even want to include a key or some labels, and labelling what's happening at each stage.

Pause the video and complete that for me now, please.

Great, now everybody's diagrams might look a little bit different, but let me show you an example.

So you might touch on something like this.

You've got your sound waves.

So your chirp being sent out by your bat, or by the bat, and then your echo that comes back, you might have included a key like I have up here, or you might have just added a label.

And then I've also labelled the sound bouncing off the object, and the bat hearing the echo which sends a signal to the brain.

Well done if your diagram looks something like this.

If you see something on mine and you're like, oh yeah, I'm going to add that to my diagram, great, just pause the video and do that for me now, please.

Great, good job.

That brings us to the end of our lesson.

Thank you for all of your hard work today, you have done a fantastic job.

If you would like to share your work then you can ask your parent or your carer to share photos of your work today with the #LearnwithOak.

Have a brilliant rest of your day.

And hopefully I will see you back here for another science lessons soon.