Fish sex -- it's weirder than you think | Marah J. Hardt | TEDxMileHigh

Did you ever wonder how fish have sex? Buckle up for a wild journey through the sex lives of everything from lobsters to anglerfish. In this hilarious talk, marine biologist Marah J. Hardt explains why sex in the sea matters, how we humans impact it, and what we can do to protect our oceans and future generations of fish.

At 17, Marah J. Hardt left high school early to study sharks in the Bahamas. There, she realized that our oceans face serious challenges and that scientists are (often) terrible at communicating them, which inspired her career in marine conservation & communication. She received her PhD in marine science from Scripps Institution of Oceanography and is working on solutions for overfishing, climate change, and the coral reef crisis. She is founder and CEO of OceanInk and the director of discovery at the Future of Fish. She wrote the book, Sex in the Sea.

This talk was given at a TEDx event using the TED conference format but independently organized by a local community. Learn more at https://www.ted.com/tedx

Right now, beneath a shimmering blue sea,

millions of fish are having sex.

(Cheers)

And the way they're doing it
and strategies they're using

looks nothing like what we see on land.

Take parrotfish.

In this species, all fish are born female.

And they look like this.

Then later in life,
she can transition into a male.

And she'll look like this.

But, it's not just a spectacular
wardrobe change.

Her body can reabsorb her ovaries
and grow testes in their place.

In just a few weeks, she'll go
from making eggs to producing sperm.

It's pretty impressive,
and in the ocean, it's also pretty common.

In fact, I bet nearly all of you have,

at some point,

had a seafood dish
made up of an individual

that started life as one sex
and transitioned to another:

oysters, grouper, shrimp,

Seeing some heads nodding, yeah?

But not all fish that change sex
start as females.

Those clownfish we know
from Finding Nemo ...

they're all born male.

So, in the real world,

when Nemo's mother died,

Nemo's dad, Marlin,
would have transitioned into Marlene,

(Laughter)

and Nemo would have likely made it
with his father-turned-mother.

(Laughter)

You can see -

(Laughter)

You can see why Pixar
took a little creative license

with the plotline, right?

(Laughter)

So sex change in the ocean
can happen in either direction

and sometimes, even back and forth.

And that's just one
of the many amazing strategies

animals use to reproduce in the ocean.

And trust me when I say,
it's one of the least surprising.

Sex in the sea is fascinating.

And it's also really important

and not just to nerdy
marine biologists like me

who are obsessed with understanding
these salty affairs.

(Laughter)

It matters for all of us.

Today we depend on wild caught fish

to help feed over 2 billion
people on the planet.

We need millions of oysters and corals
to build the giant reefs

that protect our shorelines
from rising seas and storms.

We depend on medicines
that are found in marine animals

to fight cancer and other diseases.

And for many of us, the diversity
and beauty of the oceans

is where we turn for recreation
and relaxation and our cultural heritage.

In order for us to continue to benefit

from the abundance
that ocean life provides,

the fish and coral and shrimp of today

have to be able to make fish
and shrimp and coral for tomorrow.

To do that, they have to have
lots and lots of sex.

(Laughter)

And until recently, we really didn't know
how sex happened in the sea.

It's pretty hard to study.

But thanks to new science and technology,

we now know so much more
than even just a few years ago.

And these new discoveries
are showing two things:

First, sex in the sea is really funky.

(Laughter)

Second, our actions are wreaking havoc

on the sex lives of everything
from shrimp to salmon.

So today, I'm going to share a few details
about how animals do it in the deep,

how we may be interrupting
these intimate affairs,

and what we can do to change that.

So, remember those sex-changing fish?

In many places in the world,

we have fishing rules
that set a minimum catch size.

Fishers are not allowed
to target tiny fish.

This allows baby fish to grow
and reproduce before they're caught.

That's a good thing.

So fishers go after the biggest fish,

but in parrotfish, for example,
or any sex changer,

targeting the biggest fish means
that they're taking out all the males.

That makes it hard
for a female fish to find a mate,

or it forces her to change sex
sooner, at a smaller size.

Both of these things can result
in fewer fish babies in the future.

In order for us to properly care
for these species,

we have to know if they change sex,

how, and when?

Only then can we create rules
that can support these sexual strategies,

such as setting a maximum size limit
in addition to a minimum one.

The challenge isn't that we can't think
of these sex-friendly solutions.

The challenge is knowing which solutions
to apply to which species

because even animals we know really well

surprise us when it comes
to their sex lives.

Take Maine lobster.

They don't look that romantic ...

(Laughter)

or that kinky.

They are both.

(Laughter)

During mating season,

female lobsters want to mate
with the biggest, baddest males,

but these guys are really aggressive,

and they'll attack
any lobster that approaches -

male or female.

Meanwhile the best time
for her to mate with the male

is right after she's molted,
when she's lost her hard shell.

So she has to approach this aggressive guy
in her most vulnerable state.

What's a girl to do?

(Laughter)

Her answer?

Spray him in the face,
repeatedly, with her urine.

(Laughter)

Under the sea,

pee is a very powerful love potion.

(Laughter)

Conveniently, lobsters' bladders
sit just above their brains,

and they have two nozzles
under their eye stalk

with which they can shoot
their urine forward.

(Laughter)

So the female approaches the male's den,
and as he charges out,

she lets loose a stream of urine,
and then gets the hell out of there.

(Laughter)

Only a few days of this daily dosing

is all it takes for her scent
to have a transformative effect.

The male turns from an aggressive
to a gentle lover.

By the week's end,
he invites her into his den.

(Laughter)

After that, the sex is easy.

(Laughter)

So how are we interrupting
this kind of kinky courtship?

Well, the female's urine
carries a critical chemical signal

that works because it can pass
through seawater,

and lobsters have a smell receptor
that can detect and receive the message.

Climate change is making
our oceans more acidic.

It's the result of too much
carbon dioxide entering seawater.

This changing chemistry
could scramble that message

or it could damage
the lobster's smell receptors.

Pollution from land
can have similar impacts.

Just imagine the consequence
for that female

if her love potion should fail.

These are the kinds of subtle
but significant impacts

we're having on the love lives
of these marine life.

And this is a species we know well.

Lobsters live near shore in the shallows.

Dive deeper, and sex gets even stranger.

Fanfin anglerfish live
at about 3000 feet below the surface

in pitch-black waters,

and the males are born
without the ability to feed themselves.

To survive, he has to find a female fast.

Meanwhile the female,
who is 10 times bigger than the male,

10 times,

she lets out a very strong pheromone
with which to attract mates to her.

So this tiny male is swimming
through the black waters,

smelling his way to a female.

And when he finds her,
he gives her a love bite.

And this is when things get really weird.

(Laughter)

That love bite triggers
a chemical reaction

whereby his jawbone
starts to disintegrate.

His face melts into her flesh,

and their two bodies start to fuse.

Their circulatory systems entwine,

and all his internal organs
start to dissolve,

except for ...

his testes.

(Laughter)

His testes mature just fine
and start producing sperm.

In the end, he's basically

a permanently-attached, on-demand
sperm factory for the female.

(Laughter)

It's a very efficient system,

(Laughter)

but this is not the kind of mating system
that we see on a farm, right?

I mean this is weird; it's really strange.

But if we don't know
that these kind of strategies exist,

or how they work,

we can't know what kind of impacts
we may be having,

even in the deep sea.

Just three years ago, we discovered
a new species of deep-sea octopus

where the females lay their eggs

on sponges attached to rocks
that are over two and a half miles deep.

These rocks contain rare-earth minerals,

and right now, there are companies
that are building bulldozers

that would be capable of mining
the deep-sea floor for those rocks,

but the bulldozers would scrape up

all the sponges
and all the eggs with them.

Knowingly and, in many cases, unknowingly,

we are preventing successful sex
and reproduction in the deep.

And let's be honest,
dating and mating is hard enough

without somebody coming in
and interrupting all the time, right?

We know this.

So today, while I hope
you will leave here

with some excellent
bar trivia on fish sex,

(Laughter)

I also ask that you remember this:

We are all far more intimately connected
with the oceans than we realize,

no matter where we live.

And this level of intimacy requires
a new kind of relationship with the ocean.

One that recognizes and respects
the enormous diversity of life

and its limitations.

We can no longer think of the oceans
as just something "out there,"

because every day, we depend on them
for our food security,

our own health and wellness,
and every other breath we take.

But it is a two-way relationship,

and the oceans can only
continue to provide for us

if we, in turn, safeguard
that fundamental force of life in the sea:

sex and reproduction.

So like any relationship,

we have to embrace some change
for the partnership to work.

The next time you're thinking
about having seafood,

look for sustainably caught
or farmed species

that are local and low on the food chain.

These are animals like oysters, clams,
mussels, small fish like mackerel.

These all reproduce like crazy

and with good management,
they can handle a bit of fishing pressure.

We can also rethink what we use
to wash our bodies,

clean our homes, and care for our lawns.

All those chemicals
eventually wash out to sea

and disrupt the natural
chemistry of the ocean.

Industry also has to play its part
and take a precautionary approach,

protecting sexual activity
where we know it exists

and preventing harm in the cases
where we just don't yet know enough,

like the deep sea.

And in the communities where we live,

the places we work,
and the country in which we vote,

we must take bold action
on climate change now.

(Applause)

(Cheers)

Never has it been more important
nor more possible

to fight for the solutions
that we know already exist.

But time is running out

for lobster seduction
and coral sex parties

and so many other animals

that depend on just the right temperature
and chemistry for peak sexual performance.

I know sometimes it can feel
like the problem is as big as the ocean,

but remember, nature is on our side.

Animals want to reproduce.

In fact, we've even discovered
some female sharks and rays

that when they can't find a mate,

they go off and reproduce
all on their own.

It's real-life virgin birth.

Fascinating.

Unfortunately, the strategy
can't save the species in the long term -

sex between males and females
is needed for that genetic diversity,

but the tactic can buy a population time.

And it just goes to show that in the sea,

reproduction and sex
are truly a force of nature.

And the animals are doing their part.

Imagine if we did ours

and worked with this force
rather than against it.

We can help set the mood
and then step back

and allow today's, tomorrow's,
and future generations

of fish and all ocean life

the freedom to do what they do best ...

get their spawn on!

(Laughter)

Thank you.

(Applause)