Ocean Facts

Octopuses have three hearts—two pump blood to the gills, one pumps it to the body. Their blood is blue because it uses copper-based hemocyanin instead of iron. Each of their 8 arms has its own mini-brain that can act independently—an arm can "decide" to open a jar while the central brain focuses on something else.

In 1997, NOAA recorded an underwater sound so loud it would've required an animal larger than a blue whale to make it.