Juergen Freund / Coconut / Veined octopus (Octopus marginatus) hiding in its shell home. Lembeh Strait, North Sulawesi, Indonesia.

Juergen Freund / Coconut / Veined octopus (Octopus marginatus) in a bottle cap getting a new shell to use as its home. Lembeh Strait, North Sulawesi, Indonesia.

Juergen Freund / Coconut / Veined octopus (Octopus marginatus) hiding in its bottle cap home, using a shell as a door. Lembeh Strait, North Sulawesi, Indonesia.

Juergen Freund / Coconut octopus / Veined octopus (Octopus marginatus) in its shell home. Lembeh Strait, North Sulawesi, Indonesia.

Juergen Freund / Coconut octopus / Veined octopus (Octopus marginatus) in its shell home. Lembeh Strait, North Sulawesi, Indonesia.

Juergen Freund / Coconut / Veined octopus (Octopus marginatus) hiding in its shell home. Lembeh Strait, North Sulawesi, Indonesia.

Alex Mustard / Common reef / day octopuses (Octopus cyanea) courting. The male, on the right, is rearing up and showing his mouth and tentacles, while still maintaining contact with the female. This is a rarely seen...

Alex Mustard / Common reef / day octopuses (Octopus cyanea) mating. The male, on the right, it passing his sperm to the female, on the left, by placing it under her mantle. His arm is visible on her body next to her...

Alex Mustard / A pair of mimic octopus (Thaumoctopus mimicus) mating. The male, behind, has grabbed the female and grasps her as he tries to place his sperm sac inside her mantle with his arm. Lembeh Strait, Molucca...

Alex Mustard / A pair of mimic octopus (Thaumoctopus mimicus) mating/courtship. The smaller male, right, is riding on top of the female as he tries to place his sperm sac inside her mantle with his arm. Lembeh Strai...

Alex Mustard / Pfeffer's flamboyant cuttlefish (Metasepia pfefferi) hovers just above the seabed. The largest individuals of this species, such as this one, are not as brightly coloured as the younger ones. Lembeh S...

Alex Mustard / A veined octopus (Amphioctopus marginatus) peers out from a discarded plastic bottle. Lacking a skeleton, octopuses can squeese their bodies into the smallest spaces and through the tiniest holes. Lem...