There are four species of blanket octopus that are so called because of the webbing between some of their arms. They are known for their tool use- they tear Portuguese man o'war tentacles off to use as weapons! Blanket octopuses also display extreme sexual dimorphism. The females can be more than six feet long, while the males are about the size of a walnut.
Joseph Elayani accompanied the Three P Diving Club on an outing underneath the waters off Romblon Island in the Philippines, and captured this remarkable footage of two colorful blanket octopuses. A longer video shows more amazing creatures seen on the same trip. -via reddit