True jellyfish are graceful, and sometimes deadly creatures.
Their stings may cause skin rashes, muscle cramps, or even death. Jellyfish range in size from a mere twelve millimeters to more than two meters across. Despite their often enormous size, jellyfish have no head, no skeleton, and no special organs for respiration or excretion. Their life cycle involves an alternation between sesslie polyp phase and a free-swimming medusa stage, though the medusa stage, shown in the picture here usually predominates. This image of Aurelia , aka the Moon Jelly, was taken by Chris Meyer while swimming on the beautiful reefs of Lizard Island, Australia.