"Dumbo" octopus (Grimpoteuthis spp), are the deepest-dwelling of all octopus species. They live on the seafloor or hover just slightly above it at depths of depths of 3000 to 4000 m / 9800 to 13000 ft. The similarity of their ear-like fins to the big ears of the Disney character Dumbo the flying elephant gave rise to its nickname. There are about 17 species of Dumbo octopus. | www.aquariumofpacific.org
"Females of this unusual octopus species sequester themselves in thin, translucent shells with which they drift across the open seas. Paper nautiluses, also called argonauts, secrete the shells to serve as cases for their eggs—but it has recently been discovered that they also function as air-trapping ballast tanks, which allow the cephalopods to hang effortlessly in the water column without sinking. Clever octopodes!"
The common octopus is the most studied of all octopus species. Its range in the eastern Atlantic extends from the Mediterranean Sea and the southern coast of England to at least Senegal in Africa. [wikipedia]