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Great white sharks are
exquisitely designed predators.
18-foot-long adults tip the scales at over one ton.
They chase their prey at 35 miles per hour,
and then secure it with 300 lethal, replaceable teeth.
These are the Ferraris of the shark world,
and like most fine-tuned cars, they're extremely complex.
Despite being the most famous sharks in the world,
scientists still know little about them.
Great white sharks are huge animals,
and yet they are able to move in
some of the most inhospitable and remote habitats on Earth,
and as a result, we humans just don't see them very often.
Evolutionary biologist Dr. Toby Daly-Engel
has uncovered some of the secrets
closely held by these elusive animals.
By using a genetic process made popular for crime scenes,
she's created a great white family tree.
The DNA analysis reveals that the great whites
may be great mothers, possibly great siblings,
and maybe even great partners.
Genetics is a really useful tool to help us
look at great white shark behavior
and habitat use in a different way.
Traditionally, in order to study great whites,
you have to catch them and attach a tag,
and then you have to be able to follow them.
With genetics, we don't actually have to necessarily
tag a shark, we can just get a tiny sample
as it's passing by and we can get enough information
about that animal to compare it to other great white sharks
all over the world.
Toby is fascinated by sharks,
but only recently spent time with great whites.
When I got a chance to see a great white shark
in the water for the first time,
the top of my head kind of blew off,
and it was just amazing.
It was like seeing a celebrity.
That's why she's traveled
to a remote Mexican coast off Baja, California,
hoping to learn more about great white shark
mating and reproduction.
The area where we went to see if we could find
great white shark pups was pretty remote.
It was a really amazing place,
really incredible arid desert ecosystems
right up against this flat, flat coastal bay
that had just chock full of gray whales
and as it turned out, baby great white sharks.
Research seemed to point to the shallow bay
as the place to find infant shark pups,
possibly born to females from Guadalupe Island,
roughly 220 miles away.
They will stay in the nursery habitat
until they get big enough to where they can rejoin
the adult sharks in the better offshore foraging areas.
Juvenile white sharks have been spotted
in other parts of the world, but not many.
Toby's team worked with the local fisherman
to find infant great whites in the bay.
They used a tested method to catch
and safely release the baby sharks.
(tense music)
Within a few days, they caught and safely released
12 infant and juvenile great whites,
but not before Toby took individual samples of their DNA.
I was going for a very, very small tissue sample
from one of the fins, and then was ready
with a little vial of preservative
that I could just pop it right into.
She wanted to find out if the pups
were related to known adults, or to each other.
Lots of people have collected DNA
from adult great white sharks,
but collecting DNA from babies can really help us
to shed light on of other side
of the great white shark life cycle
that we really know very little about.
We can actually find out where
they are potentially giving birth.
With most shark species,
it's common for a single litter of pups
to have multiple fathers.
Females use a strategy called multiple paternity,
which means that a female will actually mate
with multiple males over the course of one breeding season,
but instead of using that sperm to fertilize her eggs,
she will store that sperm from these multiple males
until she needs it.
Sperm from different males may mix
and so those pups that all have the same mom
will end up with different fathers.
It's thought that this is because
most female sharks have little say
about who they mate with,
but no one has ever seen great whites mate.
That would be amazing.
It would answer a lot of questions.
Great whites may be different,
and mate differently from other shark species.
One thing that makes them different
is that they're so big.
They don't tend to aggregate in big groups
like a lot of smaller sharks.
Creating a family tree could help
to understand the mysterious life cycle of this species
and ultimately help to protect them.
If we can identify baby sharks
and possibly connect them to an adult population,
we can actually make a case for
protecting the entirety of that shark's range,
from adulthood to infancy and back again.
In her Florida lab, Toby used the fingerprint
technique to compare the Baja babies' DNA samples
to an extensive database of adult great white shark DNA.
DNA fingerprinting is using little stretches of DNA
to compare individuals with a great degree of certainty,
and it's exactly the same method that crime labs use
to catch murderers, except that we are using shark DNA.
She personally took 12 samples
from the baby sharks and compared them
to a healthy database of adult white sharks.
Scientists have been getting DNA
from Guadalupe's adult sharks for decades.
Great whites can live as long as humans.
The estimate that we have right now
is they could live as many as 70 to 100 years,
so they live as long as most people,
but that might actually be an underestimate.
Females don't reach maturity
until they're about 16 years old,
and then they'll give birth to two to 15 pups
about every three to four years.
A great white pregnancy is more than
twice as long as a human's,
likely 20 months or longer.
So they don't reproduce very quickly,
they grow fairly slowly, and they live a long time,
which actually makes them a lot more similar
to mammals than to other kinds of fish.
Toby hoped to find matches between
the Baja pups and the known females from Guadalupe Island.
We were really hoping that we would see
an immediate connection with one of the adults
at Guadalupe because Guadalupe is fairly close
to this nursery site, so that was kind of the first thing
that I went to look for.
The analysis was disappointing.
It was really interesting when we saw
that the pups that we were sampling,
they weren't all just this one size of brand new baby
that had just been born that past year.
There was actually a mix of really new baby sharks
and some of the older individuals probably from
the last year or two litters that had grown up
a little bit but still hadn't left that nursery area.
As she pushed forward,
she discovered something completely unexpected.
We found multiple pairs of siblings,
specifically we found one brother/brother pair
and another sister/brother pair, full siblings,
but some of them were older than the others.
So what we concluded from that is that
even though these sharks were brother and sister,
they'd been born to the same mom
and the same dad in different litters.
Not just the same mother,
the same father too.
What's really interesting about that to me
is that that male and that specific female
mated with each other more than once.
Wherever the parent sharks came from,
they seem to have established a connection,
and while great whites aren't traditional parents,
mother sharks do what they can to protect their young.
What they do is they give birth in a place
where the babies will either be born into
or swim into a nursery habitat that is relatively shallow
and protected from really large predators.
(tense music)
Female great whites don't stay close
to their pups after giving birth
because the massive mothers need massive prey
after delivering at least 750 pounds of babies.
Once the last pup is born, they're off to find food fast.
But they do their very best to ensure
that their babies have a sanctuary where they can grow,
find food, and be safe from predators until they're bigger.
Great white sharks are intelligent.
They have a long time to get to know their environment.
They've not only had hundreds of millions of years
of evolution, but an individual from this species
can live to see potentially generations
of its own offspring join that same population.
From this revolutionary genetic study,
it does seem that siblings may stick close to each other,
possibly for many years.
It's part of their survival strategy,
as they perfect their hunting techniques.
Great white sharks as an apex predator
are in charge of keeping the other levels of animals
in the environment healthy by weeding out the sick
or the weak, the ones that shouldn't be reproducing.
These important and misunderstood predators
have even more sophisticated strategies for healing wounds
and even fighting cancer.
A new white shark breakthrough might ultimately benefit us.
This genetic study reveals great white superpowers.
Multiple scientists and organizations teamed up
to sequence the great white shark genome
for the very first time.
Great white sharks have a huge genome compared to humans.
They have almost twice as many chromosomes as we do,
and what that means is they don't necessarily have
more genes than we do, but they have different numbers
of copies of those genes.
So where we may have one or two genes
coding for, say, an antibody in our immune system,
sharks won't just have one copy of that immune system gene,
they may have 10.
(mysterious music)
Sharks have survived for roughly
450 million years, through all of Earth's mass extinctions,
and in the 16 million years great whites have been around,
they've perfected some amazing biology.
The scientists found genes that play a role
in DNA repair and damage response,
which could explain how these sharks grow to be so big
without the same occurrence of cancer that we have.
One of the things that investigators
who recently sequenced the great white shark genome found
was that a lot of extra copies have to do with
wound healing and in particular, clotting factors.
The genome of these sharks may be why
they are so effective at being a survivor in the ocean.
This healing power that these sharks have
is definitely been one of the keys to their survival.
It's almost like a great white shark superpower,
like Wolverine in the X-Men.
It may also lead to breakthroughs in medicine.
A lot of our genome evolved from the shark genome,
including a lot of our human immune system.
(dramatic music)
This amazing immune system can not just tell us
how sharks survive, but potentially can help us
gain insight into what it means for our own human survival.
(mysterious music)