A firm, dome-shaped jellyfish up to 20 cm (8 in) across, dense enough to feel like cartilage, with eight thick mouth arms and no trailing tentacles at all. Without long tentacles there is nothing to catch a diver, and the sting is negligible.
It arrives in swarms. Populations build through the season and then appear in numbers that can fill the water column for days, driven by wind and current rather than by any movement of their own - the animals swim, but not against anything. Then they are gone.
Each bell is a moving shelter. Juvenile fish, particularly jacks and drums, ride under and beside the arms, using a stinging animal as cover in open water with nowhere else to hide; they leave and rejoin as the bell drifts. Looking under a jellyfish is one of the more reliable ways to find a fish species you would otherwise never see.
Feeding is not done with tentacles either. The mouth arms are covered in thousands of tiny openings that trap plankton in mucus and pass it inward, so the animal filters continuously as it pulses.
- firm dome-shaped bell, cartilage-like to the touch, with no trailing tentacles
- eight thick mouth arms ending in short knobs
- often carries small fish sheltering under the bell
- bell up to 20 cm across
