Post all your weird/awesome underwater creature pics and info here!
I'll start with this prehistoric shark that was discovered recently near Japan:

Flaring the gills that give the species its name, a frilled shark swims at Japan's Awashima Marine Park on Sunday, January 21, 2007. Sightings of living frilled sharks are rare, because the fish generally remain thousands of feet beneath the water's surface.
Video of the shark in action! Unfortunately it died shortly only hours after it arrived at the park. 
Fish like this will not survive in captivity. Sadly, human ignorance is to blame for it's death. It's body was probably oversaturated with oxygen since it's gills are designed to filter large amounts due to the low oxygen at the depth levels it usually lives in.