Xenophora pallidula

Class: Gastropoda Subclass: Caenogastropoda Order: Littorinimorpha Superfamily: Xenophoroidea Family: Xenophoridae Genus: Xenophora

Author: Reeve, 1842

The seashells that belong to the genus Xenophora are known as a carrier shells because they have the habit of attach empty shells, pieces of coral, stones or grains of sand to their shells. In most species this only occur during their young state and the attachments are only on early whorls. In others such X. pallidula (photos) it continues throughout the growth giving a beautiful and interesting seashell. The Xenophora picks up and clean the selected object, then the animal cements the object to its shell with secretions from the mantle. Bivalve shells are placed with the inner side facing upward, while gastropods are usually attached with the aperture facing up. This process can take up to an hour and a half to complete, then the animal remains motionless for up to ten hours to ensure its new attachment is secure.

It is not known to what extent an artistic sensibility plays a part in this behavior. The seashells 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 (photos), 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 gastropod relatively thin shell.

Not all of the items on a Xenophora's shell are put there by the creature itself. As a solid substrate in a mucky environment, the shell is an enticing landing spot for tube worms, oysters, and, most spectacularly, glass sponges. Their new home even has the advantage of being mobile, transporting a rooted animal to new feeding grounds.