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THE PAPER NAUTILUS: WHAT’S THE POINT OF HAVING THREE LEGS?

Every seven years a weird but beautiful creature frequents the waters of Kangaroo Island. If you are lucky enough, you may find a paper nautilus “shell” washed up on the water’s edge at One Kangaroo Island.



The paper nautilus is the female egg chamber of an Argonaut octopus. The male is 600 times smaller and has three legs one of which is called a hectocotylus. Rather than mate in the traditional way, the male discards his third leg and projects the now detached penis towards the female. She gathers the third leg filled with sperm and fertilises the eggs protecting them within the paper nautilus shell.


The translucent white “shell” is not only a protection for her offspring, but enables this pelagic octopus to use the chamber created by the shell as a means of ballast.