Image Gallery: Holoplankton
Holoplankton spend their entire lives as part of the plankton. This group includes krill, copepods, various pelagic (free swimming) sea snails and slugs, salps, jellyfish and a small number of the marine worms. To most people jellyfish are probably the most visible and best known of this group. Australian tropical waters contain a huge diversity of jellyfish, all of which are predatory, securing their prey using stinging cells (nematocysts) or sticky cells (colloblasts). The most famous is the Bluebottle or Portuguese Man-of-War Physalia physalis, which washes up in huge numbers on Australian beaches from time to time.