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Home » Fish Sex – It’s Weirder Than You Think: Marah J. Hardt (Transcript)

Fish Sex – It’s Weirder Than You Think: Marah J. Hardt (Transcript)

Full text of Marah J. Hardt’s talk: Fish sex – it’s weirder than you think at TEDx MileHigh conference. In this hilarious talk, marine biologist Marah J. Hardt explains why (fish) sex in the sea matters, how we humans impact it, and what we can do instead to protect our oceans, and future generations of fish.


Marah J. Hardt – Marine Biologist

Right now, beneath a shimmering blue sea, millions of fish are having sex. 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, and Nemo would have likely made it with his father-turned-mother.

You can see why Pixar took a little creative license with the plotline, right?

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.

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