Читать книгу The World's Most Dangerous Animals - Kevin Baker Baker - Страница 14

Live conus textile cone snail. Image author: Richard Ling.

Cone shells, or cone snails are marine based snails that inhabitat reef-based environments in tropical and sub-tropical climates. Although they can be found in their greatest numbers in the Indo-West Pacific region. These little creatures, however, on multiple occasions have been the subjects of envenomation reports, often times fatal for human victims.

The venom from a cone snail differs greatly between individual snails, and between snail species; the venom has evolved to be optimally harmful to the snail’s prey. Cone snails generally utilize peptide toxins as the active venomous ingredient. This permits it to possess paralytic properties, stunning the victims in almost all cases. Of further interest is the injection technique of this venom. The snails possess a long duct in which the venom is produced, this duct often exceeds the length of the snail and as the venom passes through, it is squeezed by a muscular bulb and forces out hollow, spear-like teeth on a harpoon-like proboscis. After having found its prey, the snail impales it with the hollow teeth, squeezes the venom out and effectively paralyses its victim; from here the prey is ingested directly into the stomach, consumed and digested. This extremely effective mechanism is the result of an evolutionary necessity, as with it snails are able to effectively immobilize prey that would otherwise be far faster or more manoeuvrable. A cone snail will often bury itself in the sand, with just its siphon tube exposed to sense when prey strays too close, then when it senses prey within striking range it shoots its deadly harpoon, rendering the prey immobile.

Although all of the known 500 types of cone snails are venomous, the most deadly cone snail is the 'geographic cone snail', which has already caused several human deaths.

Obviously, care should be taken not to pick up a pretty looking cone snail shell up off the beach, as it could still be alive inside. For human victims, the venom can be expected to induce weakness and loss of coordination almost immediately. After which, nausea, numbness, local pain and swelling are frequent symptoms of the venom. Scarily, in extreme cases, the venom is more than capable of inducing paralysis in the victim’s lungs, which then leads to respiratory failure.

There is no antivenin to combat a cone snail's venom at this point in time. Instead, treatment involves doing everything possible to keep the victim alive until the toxins wear off.