Amphioctopus marginatus or the coconut octopus is found on sandy bottoms in bays or lagoons. It frequently buries itself in the sand with only its eyes uncovered to hide itself from predators.
The main body of the octopus is normally 8 centimeters long and including the arms, approximately 15 centimeters long. These coconut octopuses displays a typical color pattern with dark ramified lines similar to veins. The arms are usually dark in color, with contrasting white suckers. In many color displays, a lighter trapezoidal area can be seen immediately below the eye.
Why Amphioctopus marginatus are Called Coconut Octopuses?
Amphioctopus marginatus have been observed tip-toeing with coconut-shell halves suctioned to their undersides, then reassembling the halves and hiding inside for protection or deception. To protect itself, it hides among the hollow husks of coconuts. It even carry these coconut shells as an armour around it, tucking the shell under its body, sitting on it like a bowl, and moving around on tip-tentacles. This behavior of these octopuses was observed in individuals in Indonesia. The researchers filmed the octopus collecting coconut half-shells discarded by humans from the sea floor and then using these shells to hide itself, due to this behavior of these octopuses they are named “coconut octopuses”.
Diver Giving Coconut Octopus a Shell
This particular individual however has been trapped by their instincts and have made a home out of a plastic cup they found underwater. While a shell is a sturdy protection, a passing eel or flounder would probably swallow the cup with the octopus in it, most likely also killing the predator or weakening it to a point where it will be soon eaten by an even bigger fish.
this particular octopus was at about 20 meters under the water, the diver tried for a long time to give it shells hoping that it would trade the shell. Coconut octopus are famous for being very picky about which shells they keep so we had to try with many different shells before it found one to be acceptable.
If offered a shell by divers, they will test it, and if they don’t like it, they will throw it out. If they do like it, they will keep it, and often will throw out an older one that is not as good as the new one.