Mollusks include cones (including cone snails), cephalopods (including octopi and squids), and bivalves.
Cone snails are a rare cause of marine envenomation among divers and shell collectors in the Indian and Pacific Oceans. When the snail is aggressively handled (eg, during shell cleaning, when placed in a pocket), it injects its venom through a harpoon-like tooth. Multiple neurotoxins in the venom block ion channels and neurotransmitter receptors, resulting in paralysis, which is usually reversible but has resulted in some deaths.
Treatment is supportive and may include local pressure immobilization (eg, by wrapping wide crepe or other fabric bandages around the limb), immersion in hot water, and tetanus prophylaxis (see table ). Severe cases may require respiratory support.
Conus californicus is the only known dangerous cone snail in North American waters. It is present in waters of the eastern Pacific Ocean. Its sting causes localized pain, swelling, redness, and numbness that rarely progresses to paralysis or shock. Like for other cone snail bites, treatment is largely supportive. Local measures seem to be of little value, and reports that local injection of epinephrine and neostigmine are helpful are unproved. Severe Conus stings may require mechanical ventilation Overview of Mechanical Ventilation Mechanical ventilation can be Noninvasive, involving various types of face masks Invasive, involving endotracheal intubation Selection and use of appropriate techniques require an understanding... read more and measures to reverse shock.
The bites of North American octopi are rarely serious.
Bites from the blue-ringed octopus, most common in Australian waters, cause tetrodotoxin Tetrodotoxin poisoning Fish poisoning and shellfish poisoning commonly cause gastrointestinal, neurologic, or histamine-mediated manifestations. (See also General Principles of Poisoning.) Ciguatera poisoning may... read more envenomation, with local anesthesia, neuromuscular paralysis, and respiratory failure; treatment is supportive.
The large (up to 1.5 m), aggressive Humboldt squid is present off the west coast of the Americas; it has reportedly bitten fishermen and divers. Other squid species are of less concern.
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