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  • [♩INTRO]

  • Imagine you're cruising the ocean in a submarine and your lights illuminate

  • what looks like a large plastic bag floating through the water.

  • Well, lot of trash ends up in the ocean,

  • so this doesn't seem as a complete surprise

  • until the bag begins to change shape, and you realize... it's an animal.

  • Meet Deepstaria.

  • This weird-looking creature has been mistaken for a lot of things,

  • including a whale placenta and a sea monster as well as a garbage bag.

  • And less often, it's recognized for what it is: a jellyfish.

  • But it's a jellyfish that always seems to have a friend in tow.

  • And we have no idea why.

  • There are two species of Deepstaria jellies, andthey don't look like jellyfish.

  • They lack the long stinging tentacles that are a hallmark of many jellies.

  • Instead, all you see is their bell, which is very thin, fragile,

  • and extremely oversized in comparison to other jellies,

  • measuring over half a meter wide.

  • To swim, they actually ripple these huge, delicate bells, which is pretty unusual

  • and may also contribute to their shape-shifting reputation.

  • But that's not where the weirdness ends.

  • Deepstaria jellies belong to the Ulmaridae family,

  • one of the most ancient lineages of jellyfish.

  • If you're familiar with the moon jelly, they're also a member of this family.

  • Ulmaridae jellies are cousins with another order of jellies, the Rhizostomeae.

  • And some of these aren't any more familiar-looking, either.

  • Some Rhizostomae have ditched tentacles altogether.

  • Rather than tentacles, these jellies catch and eat their prey using oral arms

  • specialized appendages that help them catch food and move it to their mouths.

  • And it turns out we also see oral arms in deep sea species of Ulmaridae.

  • Then, instead of tentacles, they dot their bells with stinging cells instead.

  • This may be a more useful strategy than tentacles for catching hard-to-find prey

  • in the deep sea, and might help explain why Deepstaria is missing them.

  • Researchers believe that Deepstaria jellies are ambush predators,

  • lying in wait with their bodies spread out wide

  • until some unfortunate creature swims into them.

  • Then they close their bell around the prey

  • and cinch themselves up tight like a trash bag.

  • And nothing escapes the inside of a Deepstaria jelly alive -- except one creature.

  • Almost every Deepstaria jellyfish encountered in the deep sea

  • has a little friend living inside of it: the giant isopod Anuropus.

  • Picture your typical garden pill bug and then supersize it

  • they can get several centimeters long.

  • Scientists aren't quite sure who benefits from this relationship and how.

  • Specifically, they don't know if the jelly gets anything from this.

  • Nor do they know whether the isopod is doing any harm,

  • or is just along for the ride.

  • They do know that these isopods are great at finding large jellies like Deepstaria,

  • and then settling in for the long haul.

  • But there's still a lot left to learn about these weird deep sea critters

  • like, how do they meet up to reproduce?

  • Why are they so hard to find?

  • And why are they so appealing to those isopods?

  • But now you know about these awesome jellies,

  • you'll never mistake one for a trash bag.

  • At least, once you spot its little hitchhiker.

  • Thanks for watching this episode of SciShow,

  • and thanks especially to the isopod to our jellyfish,

  • this month's President of Space, Matthew Brant!

  • Your continued support makes this channel possible, so thank you.

  • If you'd like to help support SciShow,

  • and maybe become President of Space yourself,

  • check out patreon.com/scishow.

  • [♩OUTRO]

[♩INTRO]

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