This is how sperm whales sleep, but Matt Kaplan at Nature has the story behind this incredible shot:
…in 2008, a team of researchers off the coast of northern Chile happened upon a pod of vertically bobbing sperm whales that seemed completely oblivious to its presence. Not a single whale responded to the team’s boat until one of them was accidentally nudged, at which point it awoke and fled, along with the rest of the group. The team’s findings suggest that, unlike other cetaceans, sperm whales appear to enter short, but periodic, bouts of sleep throughout the day — an observation that Kaplan says could hint that sperm-whales are actually “the least sleep-dependent mammals known.”
