These are all from the National Geographic Found tumblr, where I accidentally spent a solid chunk of a full workday the other week. Oops.
Speaking of the last photo, Johan told me a story about a Chinese lady out on a night safari who was bit in half by a hippopotamus - apparently because it was so upset she snagged a photo of it using flash. I found the story questionable to say the least - until, that is, I saw the size and texture of the pearly-whites on that thing. (!)