Jellyfish gyroscopes to orient the eyes skyward. Certain jellyfish look upward at the mangrove canopy while making a daily migration from mangrove swamps into the open lagoon, where they feed, and back again. Box jellyfish have more advanced vision than the other groups. Each individual has 24 eyes, two of which are capable of seeing colour, and four parallel information processing areas that act in competition, supposedly making them one of the few kinds of animal to have a 360-degree view of its environment. Jellyfish range from about one millimeter in bell height and diameter, to nearly in bell height and
Jellyfish injury or even death; small box jellyfish are responsible for many of these deaths. When conditions are favourable, jellyfish can form vast swarms. These can be responsible for damage to fishing gear by filling fishing nets, and sometimes clog the cooling systems of power and desalination plants which draw their water from the sea. The name jellyfish, in use since 1796, has traditionally been applied to medusae and all similar animals including the comb jellies (ctenophores, another phylum). The term "jellies" or "sea jellies" is more recent, having been introduced by public aquaria in an effort to avoid use of