Loved by Aristotle and written about by Jules Verne, the paper nautilus, despite its name, is also known as an argonaut and is not a nautilus at all. It’s actually an octopus, and I’d suggest it is on the A-list of treasured creatures to be experienced.
When it’s time for most female octopuses to lay their eggs, they seek out a cave or other protected space. But not the argonaut. This tiny octopus makes her own protected space, a paper-thin shell. Mum and the eggs float through the open ocean inside the shell until the eggs hatch and the little ones go their own way.
The male is less than 25mm long. The female is 600 times larger and mates multiple times in her life, whereas the male only mates once and passes away. When she’s ready to lay her eggs, she uses glands on two of her arms to create a shell for both the eggs and herself. It’s as thin as a sheet of paper, and it resembles the spiral shell of a nautilus, hence its name.
At the surface, the mother takes a bubble of air into the shell. She then closes the shell and drops deeper into the water. At the right depth, the bubble allows her to float along without having to use much energy for swimming or maintaining her depth. This can help the females save energy as they drift along.
Argonauts sometimes wash up on shore, or their shells are found floating in the ocean. That convinced many that the shells were actually sails that allowed the argonaut to skim along the surface.
To find a paper nautilus is one of those OMG moments, and the sighting of shells span from Portsea through to Seaford, so it’s really just a moment of chance. Normally shells are washed up with the octopus inside. However, with the sunrise, birds are quick to eat the octopus and often break the shell to remove them from their protective casing.
By the end of an average life of a female nautilus, she will have carried several broods of eggs. Shells can grow as big as 30cm in size and just experiencing one is an awe-inspiring moment.
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