Hello everyone welcome back to another
Aquatic Adventure! I'm Erin here with
WAVE Foundation
and we are at our Surrounded By Sharks
exhibit because today
we are going to review some basics of
sharks because shark week is kicking off
on August 9th
on the Discovery channel. So I think it's
great to get a little bit of a refresher
of the basics of what a shark is, how
they live and survive,
and what their role is out in the
ecosystem. So that's what we're going to
cover today. We have some sharks swimming
around. Dan is one of our sand tiger sharks. He's
about to come up real high you may not
get to see him
and then I think I have Cal here, our sand tiger shark swimming
right at us. I'll try and identify other sharks
that I see swimming around me. Can you see Dan yet?
Oh there he is. He's right up there. He's really high though so you may not be
able to see him. So, sharks! The first question. The first
important thing for us to review about
sharks...
What are they? Right, what kind of animal
are they?
For aquatic animals oftentimes we jump straight to "fish" (which for sharks
is actually accurate) but in the ocean we can have mammals,
whales, or reptiles, sea turtles, and so there are
lots of other types of animals that live
in the ocean but sharks do fall into the
fish category. Now if I were to have asked you just to
name a fish before this, a lot of us might name Nemo or bass or
bluegill, if we like to fish. So how do all those things and all
those fish fit together? They're
really different but they are all fish.
There are two main differences between
sharks and all those other fish that we
would have named and the first one is about their gills.
They use gills to breathe because they breathe
the air or the oxygen out of the water. Rather than us who
breathe the oxygen out of the air. We
have lungs for that. Here's a shark ray.
So they have gills but Nemo, bass, and
bluegills, they all only have two gills.
Now if we all make a fishy face, please
do this with me!
Our hands are mimicking the gills on
fish. They have these
slits on the side of their head that
flap open and closed
and that is where they breathe. Those are
their gills. But they only have two,
like our hands. Sharks however have
five gill slits on each side of their
head so that means they have
ten gills, at least. There are some sharks
that have six gills on each side or
seven gills on each side. Creatively they
are named the six gill shark and the seven gill
shark. Science, we are very logical. So sharks have
five gill slits on each side. That is a
very big distinction between them and
some of the other fishes. They need
more oxygen as they swim
and to keep their body processes running.
Also a challenge for you. If you're
buying
shark gear, check to see if it has the
right number of gill slits.
A lot of them don't. So we have the gills
that's an important difference.
The other thing that's a really
important difference and really
important for shark survival
is what their body is made out of. You
and I, we are made out of bone. Our skeleton is
bone. That helps us to stand
up straight. That helps us to run on land,
walk on land. They don't have to be on land at all so
they actually don't need to have
bony skeletons. They actually have
cartilaginous skeletons, 
which means it's made out of cartilage.
Now you all might be thinking, "I  feel
like I've heard that word, cartilage."
We have cartilage in our body. A couple
of easy places to see
what it is and how flexible it is. The
best one is your ear.
So the top of your ear, not the
bottom, but the top of your ear. If you
feel that sort of hard but
really wiggly still, part inside of your
ear, that is cartilage! Now imagine for us
humans if our entire
skeleton was made like the top of our
ear and our whole body was this wiggly. Would
we be able to run around, play soccer, walk even? No!
Most students tell me that we would be a
blob on the ground. Which I think is
probably accurate. So we would not be
able to survive with a cartilaginous
skeleton.
But fish in the water, or sharks
specifically, are
able to have that really flexible body
because they don't have to stand up on
land. So while they swim, what that actually
allows them to do is be
very flexible. This cartilage is how they
are agile, or able to move quickly, in the
water.
Sharks, when they are swimming and they
want to change direction. If they're
swimming forward and they want to decide to go this way (pointing)
rather than just, you know, make a big arc.
That's not very efficient!
They will often fold their body almost
in half,
like a C and then go back the other
direction. And they would not be able to
do that if it weren't for
this cartilage skeleton. So they are very
very flexible. Now the last thing we're going to cover
as our basics, is how important they are
to the ocean ecosystems. A lot of us are
nervous about sharks because they are
predators.
And that's totally valid they are
predators. They are carnivores.
They have to eat meat. So they're going
to eat other fish,
and things that are swimming around, like 
seals, sea lions.
But that is a critical role that they
play in the ocean.
By eating those animals and because they don't want to expend too much energy, the
sharks, they actually eat the sick or dying fish
first. And so that actually helps to keep
the other
ocean populations healthier because they
pick off
the sick fish before hopefully that
passes to other fish.
So sharks are really important to
keeping the ocean ecosystems all healthy
and also in balance. If they weren't here
and those
top predators were not there, all the other
grazing fish, the smaller fish that maybe
eat
algae and seaweeds, they would
overpopulate.
And then there wouldn't be any seaweeds
because they would eat it all.
So those top predators are really
important to keep the balance of the
oceans there and in check. So
sharks are incredible animals. They are
built perfectly to live and survive in the
ocean and to be those top predators,
to keep our ocean ecosystems in balance.
I hope you guys
enjoy sharks. Do a little bit more
research maybe before we dive into shark
week.
But get excited to learn all about
sharks and these incredible ocean
predators throughout Shark Week! Enjoy!
