Conus marmoreus feeding on another snail (Courtesy of Jeanette and Scott Johnson)The marbled cone snail, like all members of the Conus genus, has adapted a very sensitive and flexible siphon, which has chemoreceptors lining the inside to detect the presence of their prey.  Studies have shown that a cone snail in an aquarium will exhibit predatory responses (such as burrowing under substrate with only siphon sticking out) as soon as a prey item is introduced into the aquarium.  A cone snail may even do this if water that a prey item has recently been in is added to the aquarium.  In the photo below, you can see the snail's black and white siphon above its proboscis.

The marbled cone snail's siphon and proboscis (Courtesy of Jeanette and Scott Johnson)Since cone snails are not known for their speed or strength, yet are still carnivorous predators, they had to adapt an efficient and fast-working venom.  More on these venoms can be found in the Venom Facts portion of this webpage.  Another example of a venomous animal is the Southern Pygmy Rattlesnake.  The venom found in cone snails is used with a modified radular tooth.  Members of the Gastropod class are known for their radula, a tongue-like organ which functions similar to a conveyor belt by scraping food off the substrate with its rows of teeth and bringing it to the snail’s mouth.  This radula is modified in carnivorous snail species, as shown below.  Radular teeth of the Conus genus are long, barbed, and harpoon-shaped, as is also seen in Conus magus, another cone snail.  They lie in a quiver-like region in the base of the proboscis.  The poison is stored in and secreted by a poison duct, which is longer than the shell of the animal itself.  To find out how the siphon and harpoon are utilized in capturing prey, visit the Nutrition page.
Examples of the modified radular tooth found in cone snails (Courtesy of Dr. Jason Biggs)
Another adaptation by the marbled cone snail is something called torsion, which all members of the Gastropods have undergone.  Mollusk bodies are separated into three parts: head-foot, mantle, and visceral mass.  Torsion is a 180 degree twist in the body components relative to the head-foot.  While this means the snail takes in food in the same area it excretes waste, it also allows for better ventilation of gills, as well as enabling the snail to withdraw its head into its shell quicker.

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