picture a polar bear in the desert no
what you're imagining is way too cute
take off the sunglasses and the swim
trunks there he's hot he's hungry he's
downright miserable why is he such a
grumpy bear well it's because he's not
where he belongs there aren't any tasty
seals to eat no cold water to enjoy and
no snow to sleep in the desert isn't his
habitat you know that a habitat is the
area where something lives but from
polar bears to porcupines animals don't
just need a place to live they also rely
on the other living and non-living
things around them to survive and life
looks different in different places
around the world so what makes a habitat
a home
well what do you need i need sandwiches
pancakes carrots maybe some nice peaches
so i need food and i need water i need a
place to live and i need a place to film
crash course videos you could say this
is my habitat animals need these things
too food water shelter and space to live
for animals their food comes from their
neighbors the other living things in
their habitat you know that plants and
animals all fall somewhere along the
food chain which is a model we use to
describe the flow of energy between
living things but the real world is made
up of lots and lots of food chains and
those chains can get kind of messy i
mean look at our polar bear sure his
favorite food is seal but in a pinch
he'll eat walrus dead whales bird's eggs
and if he has absolutely no other choice
plants the polar bear is at the top of
multiple food chains and that's not
unusual most animals don't just eat one
thing and neither do i i'm at the top of
the pancake food chain and the carrot
food chain it just so happens i prefer
pancakes so you can see how food chains
are actually all tangled around with
each other with many different ones
overlapping kind of like a web so we
call this a food web food webs are big
tangled systems that include every plant
and animal in a habitat and as you might
guess all food webs are different let's
compare two different habitats to see
how the food webs play out
first we'll go back to our old stomping
ground the forest let's begin with you
know this people the plants trees grass
and other plants that change energy from
the sun into sugar but then you have
some animals that eat other animals this
is where things get a little more
complicated today an owl makes a mouse
his lunch but tomorrow it may be a
rabbit today a snake snacks on a
squirrel but a few days later our owl
friend might make a meal of another meat
eater like the snake finally the
decomposers insects fungi and bacteria
are breaking down whatever's left over
from uneaten rotten fruit to leftover
animal carcasses as they break down
matter they provide more nutrients for
the plants it's a bit of a different
story up in the arctic i mean look at
all that ice i know what you're thinking
where are the plants how do we have a
food web without plants zoom in on the
sea water zoom way in further further
stop can you see those tiny plants
they're called phytoplankton and just
like plants on land they convert energy
from the sun really small creatures
called zoa plankton eat the
phytoplankton in all kinds of small fish
dine on the zooplankton larger fish eat
the smaller fish there are big marine
mammals too beluga whales eat fish while
humpback whales eat the tiny plankton
and krill and what else eats fish seals
that's our polar bear's favorite food
but up here you can't afford to be picky
so we may have to nibble on some whale
carcass if necessary as for decomposers
there aren't many bugs or earthworms in
this cold climate there are bacteria but
since it's so cold the decomposers break
down matter much more slowly than in the
forest
so you can see food webs and the
ecosystems that support them look
different in different parts of the
world depending on the habitat
conditions flat or mountainous land more
or less water
these seemingly small changes in
habitats affect what kind of plants and
animals live there up in the arctic a
polar bear has the right conditions to
keep him happy first he fits into his
food web perfectly the food that's
available to him has enough fat and
protein to keep his energy up second he
fits into his habitat perfectly he has
the body adaptations to not just survive
but feel really comfortable in the super
cold a polar bear isn't built to survive
in the desert or the forest so let's put
our poor polar bear back where he
belongs i was starting to feel bad for
the guy