Danielle de Carle

We found the first leech fossil that has ever been recorded.

Oh, yeah.

So parasitism is a type of symbiosis.

And symbiosis is basically just a situation where you have individuals from two or more species that live together in very close association for a long period of time.

And they're adapted for this purpose.

And parasitism is like a specific form of symbiosis where you have one organism that lives inside or on another organism.

That's called the host.

And the parasite gains nutrients at the expense of the host.

And it has some kind of adaptation for doing so.

So it's either eating little bits of the host or it's kind of stealing nutrients from the host.

So like you said, when we think about leeches, most of the time we think about ones that feed on our blood, right?

Or the blood of other vertebrates.

But today, there are lots of leeches that don't do that.

So some of them, they'll swallow basically anything that can fit in their mouths, or they'll bite off chunks of dead bodies and things like this.

And then we have...

Other leeches in the kind of modern biota, I suppose.

So they'll suck on the bodily fluids from things like crabs and shrimp.

They'll kind of attach and stick their mouth parts in the little membranous parts between the hard plates.

Oh my gosh.

And they'll suck out the bodily fluids in that way.