In a large part of gastropods the radula consists of a variable number of chitinous teeth, of different shape and measure, situated in the anterior share of the pharynx, just after the proboscis, by which the food is literally scraped.

In the Family Conidae, together with the Familia Terebridae and Turridae, it’s evolved a peculiar shape of radula reduced to a sharp and grooved tooth, fit to harpoon and inject the prey with a potent venom. In the primitive Toxoglossa the radular teeth are placed in several rows and may protrude to scrape the food. Rising the evolutionary scale, the teeth become more and more spears-like and loose their primitive function. They are then contained in a sac that isn’t in a direct communication with the proboscis.

The radular system of the Genus Conus consists of three parts: the venom bulb, the venom duct and the radular sac. The bulb doesn’t produce the venom but seems to have the function to pull it through the duct, where it’s elaborated, up to the sac in which the teeth are located. The bulb, that represent the more remarkable part of the system, is kidney-shaped with a sharper apex from which the venom duct starts. The radular sac varies in shape and dimensions depending on the species and it’s constituted by two distinct parts: the reserve sac that seems to have the function to bear new teeth and the ready sac that contains only few well shaped teeth. The radular sac is attached to the oesophagus near the base of the proboscis, in the opposite side compared to the genital orifice.

Teeth in several phases of growth are situated inside the reserve sac, each of them joined with the sac itself by a thin sheath. Each tooth completely shaped is transferred, in a still not well known way, from the reserve sac into the ready one and from it to the proboscis, where there is always at least one tooth ready for the use. In this way the teeth are filled with the venom.

The venom is a yellow-whitish fluid, rather viscous, with a basic pH (7.8-8.1). It’s relatively immune both at high and low temperatures and it keeps highly poisonous after a thermal treatment too. The venom chemistry is still little known and it’s rather complex.

The shape and dimension of the teeth is in relation to the feeding habits of the Conus - which, from this point of view, may be distinguished in piscivorous, molluscivorous and vermivorous - and varies according to the species. The teeth may be either very small in some vermivorous cones or very long, till twenty millimetres, in the great sized piscivorous ones. The number of the teeth may vary from about ten to more than fifty.

The piscivorous cones teeth are provided with hooks in the terminal part and have a long polished shaft without cusps at the base. The teeth of the molluscivorous cones are characteristic of many serration and a strong cusp near the base. The vermivorous cones teeth are rather short with small hooks and strong serrations; in the middle of the shaft may be an elongated relief. But the more manifest feature is a strong cusp set at the base and bent forward. It’s been supposed that this structure works to keep the tooth inside the proboscis after the prey has been harpooned. In this way the cone would be able to extract the worm from its hideout more easily.

The shells of the vermivorous cones have a rather narrow aperture. The shells of the molluscivorous cones have a narrow aperture too and are characteristic of tent patterns. On the contrary, the piscivorous ones have a very wide aperture.
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