Whether you go around the block or around the world, you'll find some amazing plants
and animals here on planet Earth.
And we'll be traveling far and wide as we tour the Earth's ecosystems.
Ecosystems are places where plants and animals live.
These living things interact with everything around them, the soil and air, sun and rain.
Together, all of these things make up a unique environment that scientists call an ecosystem.
There are many different kinds of ecosystems, including forests, oceans and streams.
But today, we'll be visiting deserts and grasslands.
As we explore, we'll find that deserts and grasslands have some things in common.
But they also have plenty of differences.
Deserts are the driest places on Earth.
There's not enough water or food for many large animals, but small ones like reptiles
can live there.
Most deserts are hot and dry all year round, while grasslands have hot summers and cold
winters with snow or rain throughout the year.
More moisture means more plants can grow in grasslands, and you'll find a whole bunch
of different animals there that eat the grass.
But where would be a good place to go to find out about these ecosystems?
It wouldn't be easy to visit them all, but there is one great place to start, at the
zoo.
There's nothing like a day at the zoo to check out your fellow residents on planet Earth.
You can see some creatures you've never seen before, visit some old friends, and learn
about the ecosystems they all come from.
You can even think of an ecosystem as a neighborhood.
Today we are looking for some animals from the desert and grasslands ecosystems.
And maybe we just found one!
Whoa!
What's that?
Where does it live?
What does it eat?
And why does it have that giant tail?
Gee, these kids sure ask a lot of questions.
I'm a Gila Monster, and the ecosystem I call home is the desert.
While Gila Monsters are native to the deserts of southwestern United States and Mexico,
our distant cousins live in deserts all over the world.
By the way, we're not actually monsters.
We are reptiles.
We reptiles love to sunbathe to keep our bodies warm.
We also like the desert's interesting rock formations.
They are perfect to crawl under when we need some shade.
And of course, there are those tasty little rodents to munch on when we're hungry.
Ah, home sweet home.
The rocks and soil of the desert where the Gila Monster lives are called its habitat.
You can think of a habitat as a plant or animal's house.
I'll bet you know one thing about the desert.
It's dry.
All desert ecosystems get less than 25 centimeters or 10 inches of rain per year, and that's
not much.
There are deserts on every continent of the world, but they don't all look the same.
The deserts of Africa cover nearly a third of the continent and are almost as large as
the whole United States.
Some parts of these deserts get no rain for years at a time and are covered by sand and
gravel.
The Arabian Desert on the Arabian Peninsula has the largest sea of sand dunes in the world.
The deserts of North America don't have many sand dunes.
What they do have are the cacti and sagebrush you might see in an old cowboy movie.
Do you live in a desert?
If not, when you look outside your window, chances are you might see some clouds in the
sky.
In most ecosystems, clouds keep the sun's hot rays from heating up the earth during
the day and keep in some of the day's warmth during the night.
But desert skies have few clouds, so the sun shines down, causing daytime temperatures
to soar.
At night, deserts get pretty cold.
Sometimes the temperature even drops below freezing.
Deserts can have strong winds because there's little in the way of trees or hills to block
them.
Sometimes, sand can fly all the way from the Sahara Desert in Africa, across the Atlantic
Ocean to South America.
Deserts are not great places for most plants to grow.
There's plenty of sun, but plants also need water, and there just isn't much of that.
And since water is so scarce, desert plants have special adaptations for getting water.
Some have shallow roots that work like drinking straws, spreading out in many directions to
suck up any rain that might fall.
Others have roots that tap deep into underground water sources.
Sometimes these roots go as deep as 30 meters or 100 feet down.
And in the desert, keeping water is just as important as getting it.
Many desert plants have what you would call a water storage tank.
They store water in their fleshy leaves and stems.
The saguaro cactus and some other desert plants have spines that act as armor to prevent thirsty
animals from attacking them for their juicy pulp.
Its cacti also have a waxy coating that seals in water, like the aloe vera plant.
The aloe vera is a good example of a plant that keeps its moisture sealed inside to help
it stay moist in a dry desert environment.
Native peoples have used aloe vera as an ointment for burns and skin irritation for centuries,
and many people still use it today.
Desert animals like myself are also well adapted to the harsh conditions of the world's driest
habitats, and my desert neighbors are going to teach you some of the tricks of the trade.
It certainly seems like deserts would be hard places for animals to live, but there are
a lot more animals living here than you might think.
They all share the same neighborhood, the same ecosystem, but you might have to look
hard to see them.
Many desert animals are experts at camouflage.
Camouflage is an adaptation designed for survival, so hungry hunters don't spot and eat them.
If you go out looking for desert animals, hopefully you won't be afraid of the dark,
because you might have to look at night.
Why?
Because many desert animals are nocturnal.
That means they rest during the hot day and are active at night.
They beat the heat by hiding from it, spending the days resting in caves or underground burrows.
Then they come out to hunt and eat in the cool of the evening.
In fact, so many desert animals are nocturnal that some people say the desert comes alive
at night.
Better bring a flashlight.
Desert reptiles also have some other interesting adaptations.
Reptiles like snakes, lizards, and tortoises are cold-blooded, which means they rely on
the sun to keep their bodies warm or cool.
All they need is a spot that's the right temperature, a rock in the sun to warm up in the morning,
or a burrow underground to stay cool in the middle of a hot day.
Reptiles also have dry, scaly skin that helps them live in the desert.
It holds in water like the waxy skin of desert plants.
Some desert animals have special tools that help keep them well-fed, which is especially
useful in an ecosystem where food is scarce.
The tarantula, scorpion, and some snakes are venomous.
They have poisonous bites or stingers.
That way they can be pretty sure their meal won't get away.
You could say their niche or job is to hunt and eat prey, like rodents and insects.
Did you know that we Gila monsters are also venomous?
In fact, we're proud to be the only venomous lizards in the United States and one of only
two species in the world.
Hey, where'd everybody go?
I promise I won't bite, unless you're a yummy little rodent.
But seriously, our best trick is our tail.
When we have a big meal, we store the extra nutrients in our tail.
It's kind of like taking a doggy bag from a restaurant.
Our tails can actually double in size when they're full.
Then, when there's not much food around, we can draw on that stored food energy to
survive.
In addition to snakes and other reptiles, there are many small mammals in the desert,
too.
Mammals are animals that have hair and produce milk to feed their young.
You won't find many large mammals in the desert, both because there's not much plant life to
graze on and because there are few places large enough for them to hide from the heat.
But the oryx, a desert antelope, has a special niche in the African desert.
The oryx can get water without drinking.
It actually gets almost all the water it needs from the plants it eats.
Mammals are also exceptionally well-adapted to desert life.
Many people think they store water in those humps, but actually, the humps act more like
fuel tanks.
They're made of fatty tissue that the camels use when food is in short supply, like the
fat stored in the Gila monster's tail.
Camels can go five to seven days without eating.
And you might expect the desert is a difficult place for people to live.
To survive, they need to find ways to adapt their environment to their needs.
One way people change the desert environment is by bringing in water from nearby rivers,
or pumping it up from deep underground wells.
This is called irrigation.
And with water, the soil can grow many plants, turning deserts into farms.
If the amount of rainfall in a desert increased a little over the course of a few thousand
years, it wouldn't be long before the desert began to bloom.
And soon it might become a different but related ecosystem, a grassland.
Cool, prairie dogs.
Gee, those kids seem pretty excited to see me.
I'd take them for a personal tour of our underground burrows, but they just get stuck going down
the holes.
Welcome to my world.
Many prairie dogs live in the grasslands of North America.
Grasslands have flat or gently rolling land and strong sun and winds, a lot like deserts.
But grasslands get more water, which is a good thing for us prairie dogs.
I mean, what do I look like, a camel?
While deserts only get a little rain each year, grasslands get between 25 and 88 centimeters.
That's between 10 and 35 inches.
The extra water means grass and other plants can grow, which means dinner if you're a prairie
dog.
There are as many as 10,000 different types of wild grasses in grasslands ecosystems,
some that look like our lawns, and some that blossom into beautiful flowers.
In fact, for all plant-eating animals, called herbivores, grasslands are like a giant salad
bar.
Many different animals live on the grasslands.
Large animals like wildebeests find their niche in the grasslands of Africa.
One animal that loves the grasslands of North America is the hummingbird.
Karen Krebs is a scientist who studies these tiny, colorful birds that feed on the grasslands
flowers.
They have long bills, and they also have very long tongues, so it makes the bill even longer.
They'll stick the bill into a flower, and they're actually lapping up the nectar, just
like a cat or a dog would lap up water.
When you see hummingbirds, you hear a hum sometimes, and that's because their wings
are beating something like 80 times a second, so you hear that humming sound, which is what
gives a hummingbird their name.
Hummingbirds, butterflies, bees are examples of pollinators, and pollinators actually feed
upon plants.
They're getting sugar as a reward for fuel for flying, and what the plants are getting
in return is pollen to help them create seeds or fruits.
Animals, insects, and birds aren't the only ones who find their supper on the grasslands.
Because everything grows so well in this ecosystem, grasslands have become some of the most important
farming areas.
Grasslands are found on most of the world's continents.
They're in many different countries, so they have a lot of different names.
The grasslands of North America's Great Plains are called prairies, while those found in
South America are called pampas.
The grasslands of Europe and Asia are called steppes, and they are some of the world's
largest grasslands, but Africa has the very largest grasslands in the world.
Some are called velts, and some are called savannas.
They cover almost half the continent.
For people, grasslands are one of the ecosystems we depend on most.
They grow almost everything we eat and wear.
Think about a typical morning.
Cereal, breads, waffles, and pancakes come from grains grown on grasslands.
Eggs come from chickens that eat grain, while milk comes from cows that graze on grass.
And your clothes are made of cotton from plants that grow on grasslands and from the wool
taken from sheep that graze there.
Grasslands can be very productive, growing millions of tons of grain in other crops for
people and animals to use as food, but sometimes there are problems.
When grasslands are poorly managed, they can turn into deserts.
That's what's happening in Africa.
Only 100 years ago, areas like this were natural grasslands with many species of animals, but
people needed to use it for farms to grow food.
The farm crops didn't protect the topsoil like the native grasses, so the soil blew
away, creating more deserts.
But many farmers around the world now use special techniques to keep that from happening,
like planting trees and brush between fields to act as windbreaks so the topsoil doesn't
blow away.
Where do you think it's harder for plants to grow?
In a grassland or a desert?
Or does it depend on the kind of plant?
We're doing an experiment to find out.
By creating models of both a desert and a grassland ecosystem, we can see which kinds
of plants do best in each.
To do this experiment, we'll need four containers for growing plants, some sandy soil, some
garden soil, water, grass seeds, four small desert plants like cactus, gloves, a ruler,
and some paper to draw or write what you see.
Fill two of the containers with sandy soil and two with garden soil.
At one end of each container, plant the cactus.
Scatter the grass seeds on the soil at the other end.
Now water each container equally, enough so the seeds will be able to grow.
Then set the containers in a warm, sunny spot.
You now have four containers of the same plant life, but with different soils.
You have the dark, rich soil found in grasslands ecosystems, while the others have the loose,
sandy soil found in deserts around the world.
Every few days, check your plants out and take some notes on how they're doing.
Then give one of the sandy soil containers and one of the garden soil containers plenty
of water.
Give the others just a little.
After several days, you'll notice the grass seeds grew better in the wetter soil.
But what about the different soil types?
Did they affect the growth of any plants?
You'll see that the types of plants typically found in grasslands grow better in the dark,
rich soil with enough moisture, while those planted in the sandy soil don't look as healthy,
and the grass seeds in the sandy soil with very little water did the worst of all.
But what about the cactus?
It looks pretty good in all cases.
Desert plants will thrive in rich soil with a lot of moisture, but they don't need it
to survive because they have adapted to live in dry, sandy deserts.
So as you have proven, the ability of a plant to grow in a specific ecosystem has a lot
to do with what types of adaptations that plant has to survive in a given area with
specific soil types and rainfall amounts.
Oh, a lion!
It must be a female lion, a lioness, since it doesn't have a mane like most male lions.
I wonder what ecosystem it lives in.
Based on the ecosystems we've explored today, we could probably figure out where this lion
would be found.
Remember that deserts are hot and dry, while grasslands get more rain.
Grasslands are the kind of place a protective fur coat might come in handy.
Deserts are places where reptiles and smaller mammals live, but grasslands have big herds
of grazing animals, the kind of animals that lions could eat.
Deserts have rocky or sandy soil and few places for large animals to hide, but grasslands
have grasses that make perfect hiding places for animals like the lioness.
The lions must live in grasslands!
Yes, I agree.
But hey, I have one more question.
We know where all these animals live, but in which ecosystem do we belong?
I know the answer to that.
All of them.
We're eco-explorers, ready to study ecosystems around the world.
It's all over the world.
Thanks for watching!