Paper Nautilus or Argonaut

Today I want to introduce you to one of the most fascinating marine creatures. These beautiful and delicate shells you see, didn´t belong to a snail or a crab, they belonged to an octopus, a female octopus to be more precise.

Paper nautiluses or argonauts are a group of pelagic octopuses. Unlike their ground dwelling cousins, they spend their lives drifting in the water column, so they evolved in clever ways to adapt to this environment. Argonauts exhibit extreme sexual dimorphism in size, lifespan and features. Females can grow up to 30 cm (12 inches), with their shells while males rarely reach more than 2cm (0.8 inches). Males only mate once in their short lifetime, but females can reproduce many times during their lives. Females have been known since ancient times, because of a unique characteristic, while males were only described in the late 19th century.

The most particular feature of these animals belongs to females too: they have two special tentacles that secrete calcite. After mating, they start producing a delicate papery shell, lay their eggs inside it and get cozy themselves. They capture air at the surface and then seal it inside the shell, using it for buoyancy control, like a hot air balloon. They can control the size of the air bubble to keep their position in the water column. This way they travel, following the current accompanied by their eggs without expending energy.

A paper nautilus’ shell is a rare finding, if you are lucky to find one, treat it carefully, it’s a little and delicate treasure, a part of a creature with a unique life story!