A common question is whether a seemingly lifeless jellyfish can still sting. Even when washed ashore or fragmented, jellyfish can retain their ability to sting. This highlights the need for caution, as they can pose a hazard even when appearing harmless.
How Jellyfish Deliver a Sting
Jellyfish possess specialized stinging cells called nematocysts, primarily located on their tentacles. Each nematocyst functions like a miniature, spring-loaded harpoon, containing a coiled, barbed tubule filled with venom. When triggered, typically by touch or pressure, a rapid increase in internal pressure causes the tubule to uncoil and forcefully eject, piercing the skin and injecting venom within a fraction of a second. This mechanism allows jellyfish to immobilize prey and defend themselves.
The discharge of a nematocyst is an autonomous process, meaning it is not consciously controlled. The venom, a complex mix of proteins, causes immediate pain and can lead to various reactions depending on the species and the amount of venom injected. Thousands of these microscopic stingers can be present on a single tentacle, each ready to fire independently upon contact.
The Stinging Capability of Deceased Jellyfish
A dead jellyfish can still sting. This capability stems from the independent nature of nematocysts. These stinging cells do not rely on the jellyfish being alive or even intact to discharge their venom. The mechanical trigger that causes a nematocyst to fire remains active long after the jellyfish’s death.
Factors influencing how long a dead jellyfish remains capable of stinging include the species, environmental conditions, and the time elapsed since its death. Nematocysts can continue to function for hours, particularly if the tentacles remain damp. A jellyfish drying out on a hot beach will eventually lose its stinging potency as the nematocysts dehydrate, but those recently washed ashore or still submerged in water can pose a risk. Even detached tentacles, or fragments of a jellyfish, contain active nematocysts and can deliver a sting. Avoid touching any jellyfish, whether it appears alive or dead.
Responding to a Jellyfish Sting
Immediate action can help manage discomfort and prevent further envenomation. First, safely remove the affected person from the water. Carefully remove any visible tentacles using tweezers or a gloved hand; avoid using bare hands, as this can lead to further stings. Do not rub or scrape the area, as this can cause more nematocysts to discharge.
Rinsing the affected area with seawater is recommended, but fresh water should be avoided as it can cause remaining nematocysts to fire more venom. For many species, applying vinegar for at least 30 seconds can help inactivate unfired nematocysts. However, vinegar should not be used for stings from Portuguese man-of-war, as it can worsen the reaction for this species. Soaking the stung area in hot water, as hot as can be tolerated (up to 113°F or 45°C), for 20 to 40 minutes can help relieve pain. Seek medical attention if symptoms are severe, such as difficulty breathing, chest pain, swelling of the face or mouth, or if the sting covers a large area.