These Are A Few of My Favorite Species: Carrier Shells

Xenophora pallidula from the Comotes Sea in the Philippines. Photo and shell are from C.R. McClain. Bottom view

Xenophora pallidula from the Comotes Sea in the Philippines. Photo and shell are from C.R. McClain. Bottom view

The carrier shells of the family Xenophoridae are the most remarkable bunch of snails.  Both their common name and their Latin name give away their uniqueness.  Xenophoridae in Latin actually translates to foreign carrying.  A carrier shell will cement stones, other shells, sponges, and other debris to its shell.  The individual pieces of foreign matter become larger as the snail grows and is often cemented to outer shell at regular intervals.

Xenophora pallidula from the Comotes Sea in the Philippines. Photo and shell are from C.R. McClain. Note the different snail species and the coral glued to the shell. You can all see the cage formed under the shell by the shell spines.

Xenophora pallidula from the Comotes Sea in the Philippines. Photo and shell are from C.R. McClain. Note the different snail species and the coral glued to the shell. You can all see the cage formed under the shell by the shell spines.

Why would an animal glue other things to itself, including other snails?  Shell spines serve as a wonderful defense for snails.  Obviously spines are pokey but they also increase the effective size of shell.  Pain and size make it hard of predators to manipulate the shell into their mouths and down their gullets.  Indeed, the objects also afford some camouflage.  Most interesting, is that Xenophorids stay between the shell and ocean floor to feed.  That cage of spines, or “spines” as the case may be, protects them. Nothing can get in there to munch on their little heads.

But, making spines is costly. It takes o’ so much energy and really who can be bothered?  Shell material is soooo expensive.  So instead of running down to the Home Depot to buy your own lumber why not steal your neighbor’s instead?  Or in this case steal your neighbor and use his body as a ceiling support.

Three groups of Xenophorids exist. Onustus with four species and Stellaria with five species glue small things to themselves but most of the shell remains exposed (>70%).  In contrast the Xenophora with about 20 species is ostentatious in how much bio-bling they will put on themselves.  They are the Mr. T of gastropods.

How exactly do Xenophorids glue these foreign bodies to themselves? Snails possess a mantle, thin layer of tissue that covers the body and contacts the internal shell. This is the part of the sail that secretes calcium carbonate in a protein matrix to grow new shell.  A Xenophorid will grab an object with their muscular foot and hold it place on the shell while the mantle secretes a little mollusk glue, that calcium carbonate cocktail, to fix it.

Also see

THESE ARE A FEW OF MY FAVORITE SPECIES: THE TORPEDO RAY

THESE ARE A FEW OF MY FAVORITE SPECIES: ALMOST ZOMBIE LIKE BRACHIOPODS

THESE ARE A FEW OF MY FAVORITE SPECIES: ANYTHING WITH AN INSTRUMENT ON IT

THESE ARE A FEW OF MY FAVORITE SPECIES: CARNIVOROUS SPONGES

THESE ARE A FEW OF MY FAVORITE SPECIES: SPOTTED PORCUPINE FISH

THESE ARE A FEW OF MY FAVORITE SPECIES: PISTOL SHRIMP

THESE ARE A FEW OF MY FAVORITE SPECIES: PIG BUTT WORM

THESE ARE A FEW OF MY FAVORITE SPECIES: PAINTED FROGFISH

 

 

Dr. M (1771 Posts)

Craig McClain is the Executive Director of the Lousiana University Marine Consortium. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Additionally, Craig is obsessed with the size of things. Sometimes this translated into actually scientific research. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (http://deepseanews.com/), a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.


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