Meroplankton vs. Holoplankton! In the diverse and unseen world of plankton, scientists have found that all of the zooplankton fall into one of two categories. The first group is called holoplankton. Combining the Greek words of “holo” meaning whole or entire and “plankt” meaning drifter, these zooplankton spend their entire lives drifting through the epi- and meso- pelagic zones. These organisms can range in size from tiny but abundant copepods to the extremely large gelatinous cnidarians such as sea jellies and siphonophores. These animals are incredibly important food source for both small fish such as mackerel and sardines as well as some of the largest baleen whales.
The second group is called meroplankton. This name comes from the Greek terms “mero” meaning part and “plankt” meaning drifter. This group of organisms begins life drifting throughout the sea until they grow and mature enough to settle in another area. This adaptation allows many of our favorite invertebrates to colonize vast areas of sea floor and prevents competition between parents and offspring.