The paper is behind a paywall, but I suspect the article doesn’t say because the paper doesn’t come to a conclusion, but I would guess either predation or avoiding being prey themselves.

The video is, I assume, behind the paywalled journal article. There’s really not much they can do about that.

I scrolled down and saw the video.

Thank you.

…that leech fell. Wtf is this jumping business

How dare you! That is not flying! I know what flying is!

They fly now.

That’s not flying, that’s just falling with style.