Xenopherans: Shell-Collecting Shells
From our friends at the Zymoglyphic Museum (which will be open to the public this coming weekend in San Mateo, CA — a once-a-year event):
Marine snails of the genus Xenophora collect shells, rocks, and other debris from their environment. They attach these objects to their shells at intervals during the shell’s growth. Sometimes it creates a neat radiating pattern; sometimes the effect is more that of a jumble of debris. The result for us in any case is that their collections become little samplings of a variety of faraway underwater realms.
It is not known to what extent an artistic sensibility plays a part in this behavior. The ones who live in shallower water (where there is enough light for them to be seen) probably use their collections for camouflage. The ones that live in the deeper, dark waters, such as X. pallidula, are believed to be motivated more by a desire to not to be sucked into the viscous muck in which they live. Attaching extensions to their shells spreads out the shell’s surface area and helps prevent the animal from sinking. The additions may also strengthen the snail’s relatively thin shell.