Successful Snails

Compared to other snails, cone snails, including Conus magus, are a rather primitive form of snail. Many other species within the Gastropoda have adapted greatly; they have gone from completely marine dwelling, to completely terrestrial, including Gastrocopta abbreviata, Vertigo meramecensis, and Haplotrema concavum, but the Cone Snails remain marine species with fully intact gills. Having said this, they still have gone through their own adaptations to become more efficient and successful in their habitat and in interactions with other organisms. Some of the most important adaptations that make these snails a successful species include their shell shape, sedative secretion, modified radula, and venom.

The shell of Conus magus is a very important aspect in its life. Although it could use its venom for protection from the predators that often feed on it are organisms with exoskeletons, like crabs. The exoskeleton doesn't allow for venom to be "injected" into the body of the crab, so the venom ends up being used more for predation than protection. Its main form of protection from crabs, who use their claws to pry open its shell, is the shell itself. The cone shape of the shell makes it harder for the crab to hold and manipulate the shell, giving the snail more chance of being disregarded by the crab and surviving. The shell shape also is helpful in burrowing into the ocean floor, allowing the snail to hide from predators or surprise unsuspecting fish when hunting. Although the pattern on the shell has not been known to have a specific use, in certain environments it can be helpful in camouflaging the snail in its surroundings. This is once again helpful in hiding and hunting.

Cone snails have the ability to secrete chemicals into the water in hopes of sedating fish in their immediate environment. The sedation is the first step in their complicated process of hunting. With the fish somewhat sedated, the snail can wait for it to come close, then use a combination of its modified radula and venom on the radula to capture the fish and enjoy the meal.

The radula is a unique feature to the members of the phylum Mollusca. In most of the species the radula is like a conveyor belt of tiny chitinous teeth that are used for scraping food off the substrate and into the mouth. In the species Conus magus, along with the other members of the genus Conus, the radula has been modified. Their radula instead have harpoon-like structures that contain venom (the full description can be found on the nutrition page, Meal Time). With its shell buried under the sand the snail will stick out its modified radula. Fish typically would not find the thin radula to be suspicious, especially after being exposed to the sedative, and swim right past it. As soon as the fish brushes up against the radula the harpoon is shot into it. This adaptation has allowed the snails to be carnivorous. Without this modified radula the snail would have great difficulty obtaining fish, or any other type of animal, because it would have no way of catching them. The snails are so slow that most other species in their habitat will easily "outrun" them. This radula lets them take advantage of their minimal activity level and let the prey come to them instead of hunting down the prey themselves.

The entire carnivorous hunting process could not be successful without the venom. The sedative makes the fish a little careless and the radula allows for the snail to get ahold of the fish but without the venom the fish could easily fight its way out of being eaten. The slow moving snail would not be able to put up a big enough fight against a fish of equal size and the snail would be left without a meal time and time again. The peptides in the venom result in the fish becoming completely stiff, allowing the snail to pull the fish into their mouth. If the fish was not injected with the venom it would surely not let the snail pull it into its mouth and eat it. The fish would struggle and try to protect itself from being eaten. The venom injection assures the snail a meal and also protects it from being injured by a fish fighting against it. Without the venom the snail would have no chance of catching a fish for dinner.

The body anatomy of the snail has also been important in making it so successful with no need to move onto land. The body is essentially composed of five external parts. These parts include the proboscis, siphon, eye stalks, mouth, and foot. The proboscis is the structure that contains the modified radula harpoon and is the primary structure used in hunting. The siphon is a nose like structure that too helps in hunting. This structure detects fish in the immediate environment surrounding the snail. It is also important in respiration because it directs water to the gills and therefore into the open circulatory system providing the snail oxygen. The magician's cone has two eye stalks located on either side of the mouth. Each contain an eye, however, it is uncertain how well the snails can see, if at all. The mouth is located at the anterior end of the snail where it is extended outward from the shell for consuming of prey. Lastly is the foot. This is a long muscle that runs along the opening of the shell to help move the snail along the ocean floor.

As illustrated with Conus magus adaptations are usually made in response to the surrounding environment. To learn about the habitat of the Magician's Cone Snail be sure to visit Home Sweet Home.

Return Home.

Created by Kayla Haas, BIO 203 To Check out other organism websites visit University of Wisconsin-La Crosse www.multipleorganisms.net www.uwlax.edu

Conus magus, The Magician's Cone Snail

Successful Snails