Gallery

Giant Pacific Octopus
Arguably the largest octopus species, based on a scientific record of a 71-kg (156-lb) individual weighed live.
Its spatial distribution includes the coastal North Pacific, along California, Oregon, Washington, British Columbia, Alaska, Russia, northern Japan, and Korea.

Atlantic Pygmy Octopus
One of the smallest octopus species, fully grown, this cephalopod reaches a mantle length of 4.5 cm (1.8 in) with arms up to 9 cm (3.5 in) long.
It often seeks shelter from predators in empty clamshells, beer cans or small openings, pulling the opening closed with its arms, combining sand and gravel to form a lid.

The Blue-Ringed Octopus
.Despite their small size, 12 to 20 cm (5 to 8 in), and relatively docile nature, they are dangerous to humans if provoked and handled, because their venom contains tetrodotoxin, a neurotoxin powerful enough to kill humans.
Their primary habitat is around southern New South Wales, South Australia, and northern Western Australia.

The Caribbean Reef Octopus
A shape-shifter, capable of changing color and texture to blend into its surroundings using specialised skin cells known as chromatophores. It can change from crimson to green, and bumpy to smooth, making it highly elusive.
Despite its name, it is found in tropical regions around the world, in the warm waters around coral reef environments and grassy and rocky sea beds.

The California Two-Spot Octopus
Found off the coast of California, and identifiable by the circular blue eyespots on each side of its head.
Due to their friendly temperament and relative hardiness, they are considered by most experts to make the best pet octopus.

The East Pacific Red Octopus
The most commonly occurring shallow-water octopus on much of the North American West Coast its range extends from the southern Gulf of California at least to the Gulf of Alaska.
It is also known as the ruby octopus, a preferred common name due to the abundance of octopus species colloquially known as red octopus.

The Octopus As Food
Octopus is consumed throughout the world by numerous sea-faring cultures. Here it is served as sushi, known in Japan as tako.

The Octopus In Art
The Octopus has a long history of appearing in art, including the famous (infamous?) Japanese erotic woodcut "The Dream of the Fisherman's Wife," also known as Tako To Ama (蛸と海女).
Source:
Wikipedia: Various Articles
Image Sources:
Article Illustrations:
Giant Pacific Octopus, California Two-Spot Octopus:
Monterey Bay Aquarium
Blue Ring Octopus:
Animal Spot
Atlantic Pygmy Octopus:
Facts Legend
Caribbean Reef Octopus, East Pacific Red Octopus, The Dream of the Fisherman's Wife:
Wikimedia
Octopus Sushi:
Deviant Art: Triangeli
Background Illustration:
Wikimedia
Sidebar Illustration:
Modified version of a graphic found at:
MarineBio