Researchers from James Cook University's ARC Center of Excellence for Coral Reef Studies examined stomach contents of reef sharks and conducted chemical analyses of shark body tissue to find out what they had been eating.  

Somewhat surprisingly after pumping sharks' stomachs to identify the contents of the last meal, the most common thing to find was in fact, nothing. "These results suggest that reef sharks eat small meals infrequently and opportunistically," Lead author, Dr Ashley Frisch said.

When whaling all but exterminated the Antarctic blue whale 50 years ago, the waters around South Georgia fell silent. Between 1998 and 2018, dedicated whale surveys off the sub-Antarctic island yielded a sole blue whale sighting. But a whale expedition this year and analysis by an international research team resulted in 58 blue whale sightings and numerous acoustic detections, raising hopes that the critically endangered mammal is finally recovering five decades after whaling was banned.

Marine mammals are not above the physical principles and processes that lead to bubble formation in tissues following decompression. Scientists once thought that diving marine mammals were immune from decompression sickness, but beached whales have been found to have gas bubbles in their tissues—a sign of the bends. In any case, how some marine mammals and turtles can repeatedly dive as deep and as long as they do has perplexed scientists for a very long time.