When Gastropods Attack 2

It began in Britain, in an isolated attack on a sleeping camper. Then the real horror commenced: Leech invasion makes Japan residents see red. These land leeches, or yamabiru, are normally small (a little more than half an inch long), but their gory feast on human blood causes a stunning transformation:

Yamabiru will climb into people's socks and stay for about an hour, growing five to 10 times in size. Unlike with water leeches, people don't immediately realise they've been bitten. Only later when they see their blood-soaked feet, do they realise what has happened...

Chilling.

(Of course, leeches aren't technically gastropods: they're annelids. However, all those slimy little invertebrates are doubtless allied in the war upon humanity.)