Thimble jellyfish Thimble jellyfish The thimble jellyfish ("Linuche unguiculata") is a species of cnidarian found in the neotropical Atlantic Ocean. It is a tiny jellyfish with a straight-sided, flat-topped bell. This jellyfish is the most common cause of seabather's eruption, a reaction caused by the injection of juvenile jellyfish nematocysts into human skin. The medusa of the thimble jellyfish has straight sides with sixteen grooves, and a flat top. The coronal groove between the top and sides provides flexibility. The margin of the bell has sixteen lappets (folds), the niches between these bearing alternately rhopalia (sense organs) and short tentacles (eight of
Thimble jellyfish eruption in the Caribbean and the Gulf of Mexico. This is an itchy rash of small red papules that develops in the areas that were covered by the bather's swimwear or hair. The condition does not occur immediately, but after the bather has showered or the skin has dried, killing the jellyfish larvae which react by discharging their stinging cells. In Florida, most cases occur between March and August. A similar condition occurs on the east coast of North America after exposure to the larvae of the sea anemone "Edwardsiella lineata". Thimble jellyfish The thimble jellyfish ("Linuche unguiculata") is a