Megadolomedes
This is one very large spider, hunting in and around the frog pond at night. And yes, they can swim! She could easily take a tadpole, and almost certainly does. For scale, the branch is 40mm wide.

Megadolomedes
Hunting in the dark, by stealth and without the aid of a web, she has landed a large prize. The daytime predatory dragonfly becomes night time prey.