Cone snails are marine gastropods characterized by a conical shell and beautiful color patterns. Cone snails possess a harpoonlike tooth capable of injecting a potent neurotoxin that can be dangerous to humans.
There are about 600 species of cone snails, all of which are poisonous. Cone snails live in shallow reefs partially buried under sandy sediment, rocks or coral in tropical and subtropical waters. Some species have adapted to colder waters.
Mechanisms of Injury
Injuries typically occur when the animal is handled. Cone snails administer stings by extending a long flexible tube called a proboscis and then firing a venomous, harpoonlike tooth (radula).
Signs and Symptoms
A cone snail sting can cause mild to moderate pain, and the area may develop other signs of an acute inflammatory reaction such as redness and swelling. Conus toxins affect the nervous system and are capable of causing paralysis, which may lead to respiratory failure and death.
If you see a beautiful cone-shaped marine snail, it is probably a cone snail. It’s difficult to tell whether a cone snail is inhabiting a given shell, as they are able to hide deep inside them. Since all cone snails are venomous, err on the side of safety, and do not touch it.
Unfortunately there is no specific treatment for cone-snail envenomations. First aid focuses on controlling pain but may not influence outcomes. Envenomation will not necessarily be fatal, but depending on the species, the amount of venom injected, and the victim’s size and susceptibility, complete paralysis may occur, and this may lead to death. Cone snail venom is a mixture of many different substances, including tetrodotoxin (TTX).
The prevalence and incidence of cone snail envenomations are unknown but probably rare in divers and the general population. Shell collectors (professional or amateur) may be at higher risk.
- Clean the wound with fresh water, and provide care for the small puncture wound.
- Apply a pressure immobilization bandage. Application of heat might help with pain management, but since TTX is a heat-stable toxin, the application of heat will not denature the toxin.
- Watch for signs and symptoms of progressive paralysis.
- Be prepared to provide mechanical ventilations with a bag valve mask or a manually triggered ventilator.
- Do not wait for signs and symptoms of paralysis. Always seek an evaluation at the nearest emergency department. The bite site might be painless and still be lethally toxic.
Implications in Diving
For the Diver
- If you see a marine snail with a cone-shaped shell, it is best to assume it is a species of cone snail and refrain from handling it — even if the shell appears to be empty.
- Remember all species of cone snails can cause envenomation.
- If you or someone you are diving with has been stung, seek professional medical evaluation. Any doctor should be able to help, regardless of any dive medicine knowledge or training.
- Do not neglect these injuries. Although fatalities are rare, they are possible.
For the Diver Operator
Strongly discourage your customers from handling these creatures or their shells.
- As the leader of the expedition, you have a duty of care if a diver gets injured during your trip.
- Provide first aid treatment as descried above.
- There are many folkloric first-aid treatments proposals; use common sense, and refrain from attempting any scientifically unsound solutions. Remember you might be liable.
- Make sure you have your customers evaluated by a medical professional.
For the Physician
- Treatment is symptomatic.
- Complications include flaccid paralysis.
- Observation for 6 to 8 hours is recommended to rule out respiratory depression.
- Conus toxins are composed of several proteins, carbohydrates and quaternary ammonium derivates, which can cause cardiotoxicity , convulstant activity, vasoactive effects and flaccid paralysis.
- Thermocoagulation could help denature some toxin components at the wound site.
- There is no antivenom available.
For additional information about marine life injuries, check out the Hazardous Marine Life Medical Reference Book.