Index: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Home > Plankton
Plankton is the aggregate community of weakly swimming but mostly drifting small organisms that inhabit the water column of the ocean, seas, and bodies of freshwater. The name comes from the Greek term, —meaning "wanderer" or "drifter". While some forms of plankton can move several hundreds of meters vertically in a single day (a behavior called diel vertical migration), their horizontal position is mostly determined by water movement ( currents) in the body of water they inhabit. Larger organisms, such as squid, fish, and marine mammals that can control their horizontal movement and swim against the average flow of the water environment, are called nekton. The study of plankton is termed planktology.Plankton concentration and distribution are sensitive to chemical and physical changes in the water.
1 Size groups
Plankton are often described in terms of size. Usually the following divisions are used:
- Megaplankton, 20-200 cm
- Macroplankton, 2-20 cm
- Mesoplankton, 0.2 mm-2 cm
- Microplankton, 20-200 μm
- Nanoplankton, 2-20 μm
- Picoplankton, 0.2-2 μm, mostly bacteria
- Femtoplankton, smaller than 0.2 μm, consisting of marine viruses
However, some of these terms may be used with very different boundaries, especially on the larger end of the scale. The existence and importance of nano- and even smaller plankton was only discovered during the 1980s, but they are thought to make up the largest the proportion of all plankton in number and diversity.
2 Functional groups
Hyperia macrocephala A copepod (Calanoida sp.) ca. 1-2mm long
Plankton are also divided into broad functional groups:
- PhytoplanktonPhytoplankton refers to the algal component of the plankton that drifts in the water column. The name comes from the Greek terms, , meaning "wanderer" or "drifter", and phyton or " plant". Phytoplankton, like other plants, obtain energy through the proces (from Greek phyton or plant), algaThe algae (singular is alga comprise several different groups of living things that produce energy through photosynthesis. They are generally regarded as simple plants, and some are related to the higher plants. Others represent independent lines of evolue that live near the water surface where there is sufficient light to support photosynthesisPhotosynthesis is a biochemical process in which plants, green algae, and some bacteria use the energy of light to combine water and carbon dioxide into oxygen and energy. It nourishes nearly all living things directly or indirectly, making it vital to li
- Zooplankton (from Greek zoon or animal), small protozoaProtozoa are single- celled creatures with nuclei that show some characteristics usually associated with animals, most notably mobility and heterotrophy. They belong among the eukaryotes, and are often grouped in the kingdom Protista together with the pla, crustaceans, and various other animalSubkingdom Parazoa Porifera (sponges) Subkingdom " Agnotozoa" Placozoa Orthonectida Rhombozoa Subkingdom Metazoa "Radiata" Cnidaria Ctenophora (comb jellies) Bilateria Protostomia Acoelomorpha Platyhelminthes (flatworms) Nemertina (ribbon worms) Gastrotris that feed on other plankton. Some of the eggs and larvae of larger animals, such as fish, crustaceans, and annelids, are included here.
- Bacterioplankton, bacteria and archaea, which play an important role in absorbing nutrients dissolved in the water.
Read more »