Are we interrupting the kinky sex lives of fish Marah J. Hardt
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 clown fish 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 mated
with his father turned mother.
(Laughter)
You can see –
(Laughter)
Yeah.
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.
It matters for all of us.
Today, we depend on wild caught fish
to help feed over two 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.
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.
Second, our actions are wreaking havoc
on the sex lives of everything
from shrimp to salmon.
I know. It can be hard to believe.
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,
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?
Her answer?
Spray him in the face
repeatedly with her urine.
(Laughter)
Under the sea, pee
is a very powerful love potion.
Conveniently, lobsters' bladders
sit just above their brains,
and they have two nozzles
under their eye stalks
with which they can shoot
their urine forward.
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.
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.
After that, the sex is easy.
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 lobsters' 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
3,000 feet below the surface
in the 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.
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 intwine,
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,
but this is not the kind
of mating strategy
that we see on a farm, right?
I mean, this is weird.
It’s really strange.
But if we don’t know
that these kinds 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?
I mean, 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 of 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.
(Audience: Yeah!)
(Applause)
Thank you.
(Applause)