[instrumental music playing]
NARRATOR: On Shark
Awareness Day,
these ancient fish are given
a much deserved spotlight.
Awe inspiring and
fear provoking,
sharks are among the most
popular and misunderstood
animals on Earth.
And while names like
hammerheads, bulls,
and great whites are
often the most recognized,
there are hundreds more.
In fact, over 500 species
have been discovered so far.
These species range wildly,
not only in size and shape,
but in lifestyle.
Of course, there are the
familiar apex predator sharks
that can detect one drop of
blood in 25 gallons of water,
and will even eat other sharks.
But some species
like the whale shark
are instead filter feeders.
They open their giant mouths
to suction in water containing
food, like small
plankton, that then
get captured by filtering pads.
The massive amount of
water taken in then
gets strained out
through their gills.
They can do this
all while stationary
until they get their fill.
Their natural buoyancy comes
from their body structure.
Shark skeletons are composed
of cartilage, which is lighter
than bone, and makes
them one of the most
flexible animals on earth.
But since cartilage decomposes
quickly after a shark dies,
scientists have to rely on what
remains for fossil records,
their teeth.
Luckily, sharks leave
plenty of evidence.
Having up to 35,000
teeth in a lifetime
and being replaced sometimes
in as little as 24 hours,
shark teeth are also
coated in fluoride, making
them cavity and age resistant.
Tooth-like in appearance,
scales cover sharks' skin.
This toughened skin
provides protection
against the elements and
decreases drag while swimming.
Known as dermal denticles,
meaning small skin teeth,
these scales, along
with actual teeth,
make up most records
of early sharks.
From these fossil records,
it's estimated that sharks
and their relatives have been
around for the past 400 million
years, making sharks 40
million years older than trees,
165 million years older
than the first dinosaurs,
and around 397 million
years older than we humans.
Incredibly resilient,
they have survived
all five mass extinctions.
It's been suggested that more
than 3,000 species of shark
have existed since their origin.
Unfortunately, shark populations
have been on the decline
for the past several decades.
Some are endangered
and an estimated
one quarter of shark species
are threatened with extinction.
Hunted primarily for their fins,
which are seen by some people
as a delicacy, more
than 100 million sharks
are killed each year.
Further adding to the
danger of extinction,
sharks grow slowly and
take years to reproduce,
making a rebound in the
population even more difficult.
Sharks' position at the
top of the food chain
affects the entire
ocean ecosystem.
If they disappeared, other
ocean species would follow.
So on Shark Awareness
Day, take a moment
to share the importance of
these incredibly beautiful
fish with family and friends.
With more awareness
and protection,
these ancient creatures
of the world's oceans
will continue to circle
the seas for millions
more years to come.
