Jellyfish system. Nematocysts, which deliver the sting, are located mostly on the tentacles; true jellyfish also have them around the mouth and stomach. Jellyfish do not need a respiratory system because sufficient oxygen diffuses through the epidermis. They have limited control over their movement, but can navigate with the pulsations of the bell-like body; some species are active swimmers most of the time, while others largely drift. The rhopalia contain rudimentary sense organs which are able to detect light, water-borne vibrations, odour and orientation. A loose network of nerves called a "nerve net" is located in the epidermis. Although traditionally thought
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