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  • 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)

Right now,

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Are we interrupting the kinky sex lives of fish? | Marah J. Hardt

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    林宜悉 posted on 2020/11/06
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