I just read an amazing article by Gwen Pearson about baby dragonflies.
As you know, they start life as underwater nymphs. (Mosquitoes do the same thing.) And these dragonfly nymphs breathe through the gills in their butts. They also swim with their butts— as Pearson writes, by “un-clenching their rectum, water in the rectal chamber can be jetted out at high pressure, pushing the nymph forward through the water.”
Oh, and they eat with their butts (sort of). First, look at this.
Gah! What just happened? A dragonfly nymph just went all "Alien" on a water bug! Specifically:
The ability of a dragonfly nymph to successfully snatch and grab food is directly related to its anus. The mouth-grabber is hydraulically activated. The dragonfly draws water in through the anus, clenches, then compresses its abdominal and thoracic muscles against the water-filled rectal chamber. This raises the internal body cavity pressure, and pushes the [jaws] out.
And those jaws are powerful: “the dragonfly nymphs generates a pound WITH THEIR BUTTS.”