![]() ![]() Surprisingly, many cone snail peptides act on pain targets, but it is not clear what advantage the snail would derive from numbing the prey’s pain. The complex mixture of peptides in cone snail venom blocks many ion channels and neuron receptors in prey species. Each cone snail peptide can target a particular kind of ion channel. Īnimal nerve cells contain many kinds of ion channels, whose function aids in transmitting signals along the nerve. In these diet-shifting species, the shape of the radular dart changes as well – those eating worms have unbarbed darts, while those eating fish have backward pointing barbs to help keep hold of the fish. Specimen CM 127704, photo by Tim Pearce.Ĭonus magus is one of the species whose diet shifts from worms to fish as it grows. Textile cone (Conus textile), a sea snail with venom powerful enough to kill humans. Their venom cocktail changes from worm toxins to fish toxins when they switch prey. When very young, the fish eaters are too small to eat fish, so they eat worms, then switch to fish later. At different stages of development, they can express different genes. The venom cocktail targets particular kinds of prey worm-eaters have a different suite of peptides than fish eaters. That means the peptides undergo extensive modifications after being translated from DNA, including bromination, glycosylation, and amino acid epimerization (changing from L to D, like becoming their own mirror image). įurthermore, cone venom peptides are one of the most highly post-translationally modified classes of gene products known. The rapid evolution appears to result from extensive gene duplications that provide abundant opportunities for natural selection during predator-prey interactions. They evolve twice as fast as most other known proteins. Each of the 600 or so species of cone snail has its own unique cocktail of peptides, with very little overlap of peptides among species, yielding >50,000 peptides among the cone snails of the world.Ĭone snail venom peptides are among the most rapidly evolving protein-coding genes in animals. ![]() The venom contains about 100 different peptides (short proteins) that act as neurotoxins. They use a hypodermic dart (a modified radular tooth) to inject venom. Most cone snails eat worms, some eat other snails, and some catch and eat fish. ![]() I thank the authors for their permission to use Figure 3 of their article.Cone snails live in the sea and inject venom to paralyze their prey. In their study, which includes sophisticated 3D-reconstruction techniques, the authors showed that the individual teeth start as thin, simple, plate-like structures that will gradually enroll longitudinally (think of someone rolling up a carpet) to form the hollow-cylindrical shape typical of cone snail teeth. Severtsov Institute of Ecology and Evolution, also in Moscow, described the formation of the hypodermic teeth in the Flea-bearing Cone, Conus pulicarius Hwass in Bruguière, 1792. In an article published this week in the Journal of Molluscan Studies, Elena Vortsepneva and Alexander Tzelin from Moscow University, and Yuri Kantor of the A.N. However, their harpoon-like and hollow shapes are very characteristic and distinctive from the radular teeth of other mollusks. The hypodermic teeth are part of the cone snail’s radula, a ribbon of teeth common to most mollusks. The toxins seep from the gland cells into the lumen, or hollow space within the tube, and are forced into the prey’s skin through the contractions of a venom bulb, which acts like the bulb of a turkey baster. Cone snail teeth are hollow, capable of piercing the prey’s “skin,” and dispense toxins produced in a tubular, elongated venom gland. Worms, fishes, and other mollusks, are the preferred prey items of cone snails, with each cone snail species favoring prey belonging to just one of these categories and not the others. After a strike, each toxin provokes a specific reaction on the prey animal. ![]() Each distinct species produces its own, particular cocktail of different toxins. Cone snails subdue and kill their prey using harpoon-like teeth that act as hypodermic needles that deliver potent “venom cocktails” to their prey. ![]()
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