Name: Why Hairworms Don’t Have Hair
Uploaded: 2023-10-21T17:02:31.000Z
Duration: 4 min 25 s
Description: VoiceTubeの動画で発音を聞きながら英語表現を覚えよう！学べる英語：

So you know the mind-controlling fungus that

makes its victims climb trees and all that?

Plenty of other parasites alter their host's behavior

as part of their M.O. to complete their life cycle.

But the parasites known as hairworms are doing it

with a genetic shortcoming we've never seen before.

Hairworms are missing a huge portion of genes

that are found in every other animal we know of.

And the best part is it makes their name pretty ironic.

Parasites as a general rule lead strange lives

that result in strange genetics, and hairworms fit that mold.

We know that most hairworms split their time

between freshwater and land, though a few others

are found in marine environments as well.

Well, technically most of their time is spent

inside other creatures in these habitats,

doing things like forcing their insect host to go for a swim

to let the adult worm emerge to look for a mate.

But overall, we didn't know a whole lot about them,

so researchers sequenced the genomes of two hairworm species,

And they were surprised to find their genes were very sparse.

Published in the journal Current Biology in August 2023,

their analysis revealed that hairworms are flat out missing 30%

of the basic set of genes we'd expect to find in any given animal.

And one of the key missing pieces is the ability to produce

a cell structure that is, as far as we know, universal among animals.

These parasites have no cilia, the hairlike structures found on cells.

Now, given that hairworms spend most of their time snuggled up

it's not so strange to have a reduced genome.

After all, they're not the ones doing the work

When you're a parasite, freeloading is the point.

But still, no cilia is an extreme take, even for a parasite,

because they seem so vital to, well, basically all other animals –

In single-celled organisms, these tiny hairs whip around

they get our sperm from point A to point B,

they're heavily involved in how we sense our environment.

So this key cellular feature plays a broad range of functions in cells.

And it's not just that hairworms' cells lack cilia.

It's that they couldn't make them even if they wanted to.

Their genome doesn't have the instructions to do it, period.

These gene instructions were missing in both the marine

and freshwater hairworm species that were studied,

So they're not only doing fine without cilia,

but they have been for an incredibly long period of time!

What's even more odd about this discovery is that

so they're not the type of parasite that never

And remember that cilia are crucial to animal sensory systems –

So those free-living hairworms are somehow finding mates and

reproducing without any sensory mechanism we understand so far.

Not to mention finding hosts, though once they're inside,

However hairworms are finding their way around,

This study did find a bunch of unique genes

whose functions haven't been discovered yet,

so maybe those play a key role in surviving life without cilia,

This discovery really makes us think twice about

just how much genetic equipment an organism can afford to lose.

Somehow, hairworms are pulling off life without

what we thought of as key genes for survival.

But what we do know is that hairworms are smoother

than a baby's bottom, which makes their name kind of hilarious.

you parents and teachers out there might like to know

that we have a spinoff channel: SciShow Kids.

as he goes on fun adventures and learns about the world around him.

Next Generation Science Standards for science education.

We happen to think it's a pretty great way for kids

So why not show it to the young people in your life?

Thanks for watching, everyone, and see you next time.

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Why Hairworms Don’t Have Hair

incredibly

scenario

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