Inspired by the efficient swimming motion of the bluegill sunfish, MIT researchers are building a mechanical fin that could one day propel robotic submarines. Propeller-driven submarines, or ...

A so-called autonomous underwater vehicle, it swims by wagging a tail fin like its biological brother, the tuna, and may be able to cover three times the distance of propeller-driven devices ...

Researchers believe its second fluke was either lost due to a fishing line becoming snagged around the fin, cutting off circulation, or due to it being cut by a propeller, triggering an infection.

“A propeller sliced his dorsal fin in two spots, causing the tall end of it to collapse to his left,” the institute says. “Luckily, it appears his fin has healed well.” Bottlenose dolphins ...