Hawaiian Marine Life Profiles: Invertebrates
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|Most people that live in Hawaii know about the dangerous animals found in the waters surrounding us, such as sharks, wana and box jellies, but one of the little known marine hazards is the seemingly unlikely cone snail. Cone snails are predatory animals, stinging their victims with a venomous harpoon-like tooth which can be hazardous to humans. Though cone snails primarily use their tooth to subdue prey, it can also be used defensively, stinging other animals, or humans, that get too close. Though all cone snails have venom glands, only a few species are dangerous enough to be fatal to humans.
Cone snails are generally buried in the sand or rubble during the day and are active during the night. They hunt by smell using a siphon which can be extended away from the shell's opening. Depending on the species, cones may prefer marine worms, snails (including other cones) or sleeping fishes. The venomous tooth is located at the tip of the proboscis, a muscular extension of the mouth. When the cone snails shoot fish with their tooth, they hold on to the tooth to keep the fish from swimming away. Eventually the venom, which affects the nervous system and also deteriorates the animalís tissues, takes effect, allowing the snail to eat the fish whole. By extending the proboscis, the snail can eat its prey without the snail having to leave its protective shell. If the prey is a worm or other snail, the tooth is released, because it will not be able to travel too far away for the cone to find it.
Cone snails are found in all habitats from shallow to moderate depths. Cone snails, one of the largest families of marine snails, have heavy, smooth shells. The live snails are covered by a skin-like layer called a periostracum which can either be opaque or translucent. The patterns on the shell can often be obscured by the periostracum or algal and calcareous growths growing on the skin.
There are at least 34 different species of cone snails in Hawaii, and one snail is found no where else in the world. Most cones in Hawaii are less than 3 inches, but the largest one, the leopard cone, can be up to 9 inches. The early Hawaiians used the word pupu 'ala for cone snails and pupu poniuniu (dizzy shell) for cone snails that caused pain.
Cone snails may look harmless, but they should not be handled by an inexperienced diver or snorkeler. Even experienced divers should handle them briefly, and only by the wide end, although the tooth can reach all areas of the shell. Currently, scientists are experimenting with the venom to determine if it could have medical importance, possibly in treating chronic pain. Though they can be very beautiful, even empty cone shells should be left in the ocean, since they can be inhabited by certain species of hermit crabs whose flattened bodies fit perfectly into the narrow crevices of the shell.