by B. N. Sullivan
In the last several posts we have been talking about collecting sea shells, and how divers can find shells underwater.
We strongly discourage the taking of live shells from their habitat. Taking live shells depletes populations by preventing the creatures living inside from reproducing. It also can disrupt the ecological balance of the habitat, since these creatures have roles as both predators and prey.
Previously, we offered a few tips on how to figure out if there are creatures living inside a shell. Today we would like to add a word of caution, particularly in regard to Cone Shells (Conidae).
There are hundreds of species of Cone Shells. The shells are attractive, and popular with collectors, but you should know that the snails that build and inhabit Cone Shells are venomous. Handling a live Cone Shell can result in being stung.
The Cone Shell snails are carnivores: some prey on other mollusks, others eat worms, and still others actually prey on fish! The snails have a structure that works a bit like a hypodermic syringe. They produce a venom that contains neurotoxins. They inject the venom into their prey through hollow stingers. (Technically, the 'stingers' are tiny, harpoon-like radula teeth.) Depending on the species, the venom either kills or immobilizes the prey.
There have been numerous cases documenting Cone Shell envenomation in humans. Depending, again, on the Cone Shell species, and also on the site of the sting, the result can range from pain, to paralysis, to death! So, if you see a Cone Shell in the water, understand that it is a venomous creature, and approach it accordingly.
If you are going to handle a Cone Shell to see if it is alive, pick it up carefully by the crown -- that is, the broad end of the cone. The stinging part is in the proboscis, which is at the 'nose' of the cone. Better yet, use something inanimate as a tool to flip over the shell so that its aperture faces upward. You may immediately see some part of the snail, but even if you don't, you should wait for awhile to see if the animal appears and tries to right itself.
If you find shells -- including Cone Shells -- while diving, it's convenient to carry them in a small mesh bag that you can clip to a D-ring on the outside of your vest. In any event, do NOT put a cone shell into your pocket or carry it in your hand, even if you think it is empty -- just in case!
We recommend that divers (and others) who are interested in collecting shells learn something about the creatures that formed the shells and live inside them. An understanding of how and where they live, what they eat -- and what eats them -- not only facilitates knowing where to look for them, it also provides the collector with a better appreciation of how the creature fits into the ecosystem. Today we add another item to this list of reasons to learn something about these creatures: your own self-protection.
About the photos: I took these macro photos of a live Mediterranean Cone Shell (Conus mediterraneus) on a sand flat off the coast of Dhekelia, Cyprus. As far as I know, this is the only Cone Shell species native to the Mediterranean Sea. The shell is relatively small -- about 3 cm (1.25 in). By the way, despite its appearance, that brownish structure sticking out near the wide end of the shell in the second photo is not the 'stinger'. It is the snail's operculum - a sort of lid that the snail uses to close over the shell aperture for protection when it retracts into the shell. The operculum is hard, made of material similar to our fingernails.
Curiously, we have never found an empty Mediterranean Cone Shell, so we have no examples of this shell in our collection. Fortunately, we do have several nice photos of the living species. Some long-time readers of The Right Blue may recall another post featuring this species, from 2007: Muck diving - The tale of the cross-eyed cone shell