Blanket octopus pairs are some of the undersea world’s oddest couples. What’s so startling is the size difference: Males are about the size of a walnut—less than an inch long—but some ...

The dozen or so species that make up Grimpoteuthis are called Dumbo octopuses because of the two large fins—one on either side of the mantle—that protrude like ears. Add in the octopus’s ...

Octopuses have a large nervous system, with the average octopus having about 500 million neurons or brain cells. That puts it in the same “brain range” as smaller mammals such as dogs. Unlike ...