Harpoons may seem like an instrument of the past, but they are still being used in the ocean today, and in a different way than you might be thinking.
As we explored in our previous blog (Tongue or deadly weapon?), snails have a tongue-like structure covered in tiny teeth, called a radula. The radula helps snails feed in a variety of ways including scraping algae off hard surfaces and drilling holes through other shells.
In cone shells, the radula is a harpoon-launching machine. The tiny teeth are modified into harpoons, two rows of which are manufactured in the radular sack. A tiny duct carries venom to the harpoon tooth. Once a harpoon is spent, a new one moves forward ready for the next attack.
Cones feast upon marine worms, other snails, and depending on the size of the cone, sometimes fish. The venomous harpoon paralyzes the prey, allowing the snail to more easily devour its meal. The harpoons can also act as defense against octopuses and other things that might try to make a meal out of a cone.
Several dozen species live in the warm waters of Florida and the Caribbean, but the most common to wash up on our shores are the alphabet cone and the Florida cone.
None of the cones found in this area are harmful to humans, but a harpoon from one of the larger species in the Southern Pacific and Indian Oceans can be fatal.
Cone shells are some of the most valuable shells, but remember just like all living animals, they play an important role in their ecosystem. So, its best to leave the living ones right where you find them, and of course, you wouldn’t want to fall victim to a deadly harpoon!