Cone Shells (Conidae)

Cone shells are among the shells most liked by collectors. Divers though are well advised to handle the beautiful shells with care. Because, as it is so often the case in nature: Death lurks beyond the beauty. Cone shells are the only members of the gastropod class that may be seriously harmful to man. The venomous sting of some cone shell species may be deadly even for an adult.

The main distribution area of cone shells is the Indopacific, that means the Tropical waters of Indian and Pacific Ocean. An especially large number of species occurs in the area around Australia, thus presenting one more animal group on the long list of venomous animals in that continent. The number of documented cone shell attacks mounts to about 30 cases, all of which are about divers or beach walker that wanted to pick up one of the beautiful shells, not caring about a potential inhabitant.

Mediterranean cone (Conus mediterraneus). Picture:  Hector Giourgis, Eastern Mediterra- nean Inhabitants.

The only European species is the Mediterranean cone (Conus mediterraneus), compared to that a fairly innocuous small snail, 2 - 3 cm shell length in size, living in the marine sea weed vegetation and feeding on polychaete worms.

Cone shell attacks on man are exclusively defensive.

Cone shells may be carnivorous, but their prey are exclusively smaller sea animals such as other molluscs and worms. About 70 of the larger species (e.g. Conus geographus, Conus textile and Conus magus) also feed on fish. Those are most dangerous to man, as they have the most potent venoms.

Textile cone (Conus textile, left) eating a turban shell (Turbo   sp.). Source: conchology.be (Guido T. Poppe).

A cone shell's venom apparatus is built by the same basic construction as a Roman snail's rasp tongue, the radula. 

The number of teeth in a cone shell's radula, though, is largely reduced: Only one tooth at a time is ready for application. Each one is transformed into a long slim blade rolled together to form a hollow harpoon with a barbed hook. While the pointed end serves to be stung into the prey's body, the harpoon's other end is connected to a venom gland evolved from the a salivary gland. That way, when the harpoon tooth is stung into the prey's body, venom is injected into its organism.

Cone shells' venom apparatus.

Systematics of Gastropoda: Clade Caenogastropoda: Conidae.

• Cone Shells and Conotoxins: Dr. Bruce Livett, Biochemist at the University of Melbourne, Australia, writes about Australian cone shells and their venoms. Additionally the page provides lots of information regarding cone shells.
• Conotoxine - Muskelgifte der Kegelschnecken (Conotoxins - muscular venoms of the cone shells): Lecture script with anatomical basics, function and biochemistry of cone shell toxins (in German).