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There are at least 900,000 species of insects and the ocean is the largest biome on the planet, so you would think there would be tons of insects riding the waves. But it turns out the sea skaters are the only ones weird enough to make it work.

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 Introduction (0:00)

There are bugs in the ocean, actual insects riding the waves, and I did not expect this. Maybe this isn't surprising to you, but insects are land creatures. Like, okay, yes, shrimp and lobsters are basically sea bugs. Crustaceans are arthropods, like many of the other things on land that we usually call bugs.

And don't get me wrong, I love insects. I think it's safe to say that I pay more attention to insects than the average person. I just thought that the ocean was an insect-free zone. There's already all kinds of weird stuff living there, like this very strange, sheet-like jellyfish and the isopods that I guess sometimes live inside of them. Did the ocean really need insects, too?

And for the most part, natural history has agreed with me, because, of all the 900,000 species of insects in the world that we know about--and we estimate that there are actually way more than that, like 5.5 million by some calculations--there are only 5 that live in, or really on, the open ocean, despite the ocean being the largest biome on the planet.

So maybe I should really be asking why aren't there more ocean insects? They're really good at living everywhere else. Why not the ocean? Well, turns out, life in the ocean for an insect is actually pretty hard. To survive there, you need a specific set of adaptations that definitely make you a bizarre beast.

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These ocean-going insects are called sea skaters, and they're essentially the saltwater version of water striders, those long-legged guys that you might have seen scooting across the surface of a pond or lake. Now, there are also members of this family that live in coastal waters and in mangrove habitats close to the shore, and they might be where the true oceanic sea skaters come from. Their ancestors could have gotten washed out to sea and adapted to life on the open ocean.

Because the ocean is just bigger water, right? So it seems like sea skaters should have been able to skate on out there no problem. Except, compared to other places that water striders and their cousins live, the ocean is rough. It's a very turbulent environment. constantly battered by things like high winds and harsh weather. Life as a sea skater means being able to survive massive storms in the open ocean without drowning, and that takes some pretty bizarre adaptations, like a double later of specially groomed, extremely water-repellent body hair called setae.

Yes, these insects are covered in tiny specialized body hairs that they groom using a wax from a gland on the underside of their bodies. Together, the layered structure of the hairs and the wax, along with their exoskeletons made of chitin, help make sea skaters super hydrophobic. Their bodies just repel water. The hairs also trap a later of air that keeps them buoyant and helps them breathe if they do accidentally end up underwater, and this is what allows them to stay afloat in choppy seas, along with the fact that they can literally walk on top of the waves.

Like their freshwater cousins, sea skaters are able to support themselves with their long middle and hind legs on the water's surface by spreading out their weight and exploiting the water's surface tension. Surface tension is caused by the cohesive forces that make water molecules want to stick together. Basically, the positive and negative charges of the atoms in water are attracted to each other like magnets, and that makes the surface of the water kind of like a stretchy trampoline for tiny insects.

Sea skaters propel themselves along it by rowing with their middle legs and can even jump off the surface of the water, reaching a maximum acceleration of approximately 40 G's, which is pretty extreme. For context, astronauts experience just over 3 G's during a normal launch, and even this can cause them to pass out. But it's no problem for sea skaters, who use this super ability to avoid getting eaten, not that there's much for a predator to eat.

Sea skaters are even smaller. than regular water striders, at around 4-5 millimeters long, and this might help them be less visible to hungry predators. And being tiny essentially allows them to avoid turbulence from the breaking waves of the ocean's surface, because they're so much smaller than the water's eddies, which sounds great, except how does such a tiny bug do regular big stuff, like find food and mates in the vastness of the open ocean?

Well, sea skaters seems to eat whatever floats their way, mostly things like zooplankton, dead jellyfish, and insects that have gotten washed out to sea, but they've also been observed to eat other, younger sea skaters. Out there, you kind of have to take what you can get. And as far as mates go, we don't really know how sea skaters find them. It might just be through ocean currents causing chance encounters, or the bugs might be more active participants. It's hard to figure out.

What we do know is that they lay their eggs on natural floating debris, like feathers, shells, and bits of wood, and on human-made debris, like plastic and other garbage. Surprisingly, the Great Pacific Garbage Patch, that floating mass of trash in the North Pacific, might actually be great for the sea skaters, because it gives them a lot more surfaces on which to lay their eggs. Scientists have recorded an increase of sea skater eggs in that area, which might end up having effects down the food chain for animals that eat the skaters and their eggs.

It also looks like sea skaters have adapted to a life where they might not run into food or mates for a long time by stretching out what's called their life history. An organism's life history includes all the changes it goes through in its life, from things like how fast it grows to how many offspring it has to how long it lives, and sea skaters basically do the opposite of "live fast and die young." They live slow, instead. They grow slower and live longer than freshwater or coastal water sliders.

This is probably part of the total package of adaptations that allows them to survive on the open ocean while other insects can't. It's not enough for a bug to just be super water-repellent, acrobatic, and tiny. They also need to be long-lived and lucky, and that's probably why they're the only true ocean bugs that we know of.

The pin club subscription window is open now until the end of August 8th. The entomologists among you might notice that the pin looks more like a water strider than it does a sea skater, and that was a mix-up on our end, but all Gerrids are cool, so this pin, still very cool. Sign up today, and you'll get your sea skater pin in the middle of the month and the pins after that around the time each new video goes up.

Show us your pins on Twitter at @BizarreBeasts and on Instagram and Facebook at @BizarreBeastsShow, where we'll be sharing extra info about sea skaters all month long. And, as always, profits from the pin club go to support our community's efforts to decrease maternal mortality in Sierra Leone.

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