Whales and dolphins... round the globe communication in high frequency bleeps, chirps and moans that we can scarely understand
I highly suggest that any one who dives in the marine environment to put on a dry-suit and get hit (sonically) by a sounding fin-whale. My ears are still ringing, 9 years later, and it was a small female several hundred yards away schooling some euphausiids!
Ow! I got drunk the night after that! And the bartender told me to stop yelling, and I told her I wasn't. If she'd been any closer when she 'barked', my skull would've been in several distinct pieces.
Philosophy, n. A route of many roads leading from nowhere to nothing.