Taking the trend in selfies to new depths, video cameras mounted on the fins of reef sharks in Hawaii are giving scientists new insights into what the predators do all day.

One camera showed a sandbar shark starting its morning at about 300 feet (90.9 meters) below the surface, then swimming steadily upward as the day wore on, joining a mixed school of sandbar sharks, oceanic blacktips, and scalloped hammerheads.

The whole motley crew "spiraled up like a shark tornado," says Carl Meyer, who studies sharks at the University of Hawaii, in Kane'ohe on Oahu.

Another video captured a sandbar shark leisurely swimming along a reef, then suddenly darting away as it rushed to meet up with a