Image Gallery: Zooplankton
Zooplankton are floating or weakly swimming animals that rely on water currents to move any great distance. They are usually larger than phytoplankton, ranging from tiny copepods, less than a centimetre long, to jellyfishes and colonial salps that may be metres long. There are two major types of zooplankton: those that spend their entire lives as part of the plankton (called Holoplankton) and those that only spend a larval or reproductive stage as part of the plankton (called Meroplankton).
Zooplankton are the favourite food of a great many marine animals so camouflaging themselves is a very important survival strategy. Developing effective camouflage when you live in clear, blue water is no easy matter. The best solution and the one most often used by members of the zooplankton is to be as transparent as possible or, in the case of many surface floating jellyfishes, blue.