photograph by Mehmet Salih Bilal

Eggcase of Argonauta nodosa, showing the derived double keel of the genus (via Wikipedia)

Sciartober Day 7: A female paper nautilus for the prompt: shelled. The females create the shells for protecting their eggs, but it also acts as a flotation device. Sumiiro thinline brushpen, Prismacolor fine line marker on Canson XL Watercolor.

photograph by Dennis Corpuz

Name: Greater argonaut (argonauta argo) Phylum: Mollusca Class: Cephalopoda Order: Octopoda   Family: Argonautidae   Region: A. argo is cosmopolitan, occurring in tropical and subtropical waters worldwide. A dwarf form exists in the Mediterranean Sea, which was described as Argonauta argo mediterranea, although this taxon is now regarded as invalid. Risk of Extinction: No info More Info: The female of the species, like all argonauts, creates a paper-thin eggcase that coils around the octopus much like the way a nautilus lives in its shell, hence the name paper nautilus. A. argo is the largest species in the genus and also produces the largest eggcase. (photo taken from http://adictamente.blogspot.com.es/2013/02/animales-con-nombre-mitologicos.html)