These Solar-Powered Carnivorous Flatworms Divide and Conquer
Tiny marine flatworms called acoels hunt for prey in coral reefs. They’re referred to as “plant-animals” because they’ve got a partnership with photosynthetic algae that live inside of them. But this acoel’s real superpower is its ability to regenerate any part of their body!
TRANSCRIPT
Those aren’t cornflakes.
This rock is absolutely covered with tiny marine flatworms, called acoels.
They’re not just an animal.
They’re also kind of a plant.
And they’re practically immortal.
They use simple eyes called ocelli to seek out the sunniest spots on tropical coral reefs.
Where they spread themselves out like beach blankets.
But they don’t just lay around sunbathing all day.
Acoels are also skilled hunters.
They catch prey by engulfing them with their body and jamming them into their mouth.
You can see their meal trying in vain to escape.
Also, they don’t have a butt.
Their poop just goes right back out through their mouth.
So you wouldn’t want to kiss one.
They aren’t just hunters.
These acoels are gardeners, too.
See those green dots?
Those are algae.
And those reddish cells belong to the acoel itself.
When the sun hits our flatworm friend, the algae inside produce sugars through photosynthesis.
Researchers think they share those sugars with their host.
In return, the acoel provides its, um, waste, which is kind of like fertilizer for the algae.
And the acoel protects its house guests.
Researchers think the acoels pack toxic chemicals in those reddish cells.
So predators tend to leave them alone.
Without its algae, the acoel would eventually die, even if it had plenty of prey to eat.
Scientists call a creature like this a holobiont, a single being made up of two or more completely different species.
In this case, a solar-powered predator.
But that’s not even the weirdest thing about them.
Researchers at Stanford University and the University of San Francisco are studying acoels, because of how they regenerate.
And to do that …
It’ll be OK, I promise.
You’d think getting cut in half would be a bad thing, but within minutes, the wounded front half seals up.
In a couple days, it’ll have a whole new tail.
And the back side?
It doesn’t just make a new head.
It makes two!
But it’s hard to share one body with two heads.
So each half eventually pulls away from the other.
Where there was once one acoel, now there are three!
What seemed like a moment of doom was actually one of rebirth.
But they don’t need the researcher’s scalpel; acoels can drop their tail and clone themselves on their own.
The acoel and their algae can multiply themselves like this over and over indefinitely, making them functionally immortal.
Acoels can do this because they’re packed with stem cells which morph into any body part the acoel needs to regrow.
And since they can’t hunt until they grow new heads, they’re extra reliant on the energy they get from their algae.
In these desperate times, the acoels even eat some of their algae.
Sorry!
Every relationship has its challenges.
But the acoel and its algae have a deal:
By taking advantage of each one’s abilities, they’re greater than the sum of their parts.
Hi. It’s Laura.
Guess who else could be considered a holobiont?
You!
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