Holoplankton and Meroplankton
Differences between Holoplankton and Meroplankton
A plankton is an organism that drifts in oceans, seas, and freshwater bodies. They consist of Zooplankton, and phytoplankton, which refer to the sea animals and plants respectively. Zooplankton comprises of Holoplankton and Meroplankton. Holoplankton comes from the Greek words “holo” meaning whole and “plankt” meaning drifter. These organisms are drifters for their entire lifetime. They remain in water column their whole life. They are known as permanent planktons. Holoplankton can also be phytoplankton (Alıçlı&Sarıhan, 2016)
Contrarywise, Meroplankton is derived from two Greek words “mero” meaning part and “plankt” meaning drifter. It refers to zooplanktons that remain in plankton form only for a specific period. They are planktonic during a part of the life cycle, usually at their larvae stage. This time varies from one species to another. Some will revisit the plankton during their reproduction phase. They will cease to be planktonic after they attain the ability to swim and become nektons or settle into the seafloor by changing into benthos. They are temporary water residing organisms. Meroplankton bear little or no resemblance to the adult form they will become (Stübner et al., 2016). th
According to Alıçlı&Sarıhan (2016), examples of Holoplankton are pteropods, Protozoan Ciliates, Radiolarian Gelatinous Jellyfish, Siphonophore Gelatinous comb jellies, some diatoms, radiolarians, dinoflagellates, amphipods, alps and, krill species. Protozoan Ciliates are unicellular organisms that have cilia in their body. These species mostly reproduce asexually but they can also reproduce sexually. Diatoms are unicellular phytoplankton that can exist as one or as a long chain. They are an important source of oxygen and usually the first step in the food chain. They can reproduce both sexually and asexually. Dinoflagellates are freshwater species and are about 200 micrometers. These organisms can chemically produce light. They reproduce asexually through mitosis.
Meroplankton, on the other hand, include Mollusc larvae-Veliger, Crustacean larvae-Shrimp, Nauplius, Urchins, and Polychaete among others. Crustaceans are freshwater planktons with benthic habitat. Their bodies are covered with a chitinous exoskeleton. Thus, they must shed the skeleton to undergo growth. They escape their predators by adapting to more nocturnal habits. Urchins have attractive spin and feet. At their larvae stage, they drift just like other planktons (Stübner et al, 2016).
In terms of size, Holoplankton and Meroplankton are very tiny organisms of approximately 1mm in length. However, their characteristics can vary depending on their locations. Jellyfish are the most significant groups of Holoplankton. They can grow up to 8 feet with tentacles of up to 200 feet. However, some scientists have argued that jellyfish are not plankton, but the fact is that they are drifting organisms which makes them planktonic. On the other hand, Meroplankton are eggs and larvae that are very tiny in physical size. Holoplankton are larger in physical size as compared to Meroplankton since the meroplanktons are at a larvae stage of their life cycle.
Zooplanktons are classified into picoplankton, nanoplankton, microplankton, mesoplankton, macroplankton and megaplankton based on their sizes as follows: picoplankton represents those of less than 2 micrometers, nanoplankton are those between 2 and 20 micrometers, microplanktons range from 20 to 200 micrometers in their physical size, most of the Crustaceans larvae and Mollusc larvae-Veliger fall unto this category, mesoplankton are 200micrometers to 20 millimeters macroplanktons range from 20 to 200 millimeters and megaplankton are larger than 200 millimeters.
Alıçlı, B. T., &Sarıhan, E. (2016). Seasonal Changes in Zooplankton Species and Groups
Composition in Iskenderun Bay (North East Levantine, Mediterranean Sea). Pakistan Journal of Zoology, 48(5), 1395-1405.
Stübner, E. I., Søreide, J. E., Reigstad, M., Marquardt, M., &Blachowiak-Samolyk, K. (2016).
Year-round meroplankton dynamics in high-Arctic Svalbard. Journal of Plankton Research, 38(3), 522-536