This article is about the marine organisms. For the SpongeBob SquarePants character, see Plankton (SpongeBob SquarePants)

Photomontage of plankton organisms

Plankton consist of any drifting organisms (animals, plants, or bacteria) that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. This is a list of characters from the Nickelodeon animated series SpongeBob SquarePants. Photomontage is the process (and result of making a composite photograph by cutting and joining a number of other photographs Plants are living Organisms belonging to the kingdom Plantae. The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Any water in the sea that is not close to the bottom is in the pelagic zone. An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. This article is about the body of water For other uses see SEA and Seas. Freshwater is a word that refers to bodies of water such as Ponds lakes rivers and streams containing low concentrations of dissolved Salts and other Total dissolved Plankton are defined by their ecological niche rather than their genetic classification. In Ecology, a niche (pronounced nich nēsh or nish A shorthand definition of niche is how an organism makes a living They provide a crucial source of food to aquatic life.

Definitions

Some marine diatoms - a key phytoplankton group

The name plankton is derived from the Greek word πλανκτος ("planktos"), meaning "wanderer" or "drifter". Diatoms ( Greek: (dia = "through" + (temnein = "to cut" i Phytoplankton are the Autotrophic component of the Plankton community Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly ^[1] While some forms of plankton are capable of independent movement and can swim up to several hundreds of meters vertically in a single day (a behavior called diel vertical migration), their horizontal position is primarily determined by currents in the body of water they inhabit. The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International A day (symbol d is a unit of Time equivalent to 24 Hours and the duration of a single Rotation of planet Earth with respect to the Diel vertical migration refers to a pattern of movement that some Organisms living in the Ocean 's Photic zone undertake each day An ocean current is continuous directed movement of Ocean water. By definition, organisms classified as plankton are unable to resist ocean currents. This is in contrast to nekton organisms that can swim against the ambient flow of the water environment and control their position (e. Nekton refers to the aggregate of actively swimming aquatic organisms in a body of water (usually oceans or lakes able to move independently of water currents g. squid, fish, and marine mammals). Squid are marine Cephalopods of the order Teuthida, which comprises around 300 species Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two Marine mammals are a diverse group of roughly 120 species of Mammal that are primarily Ocean -dwelling or depend on the ocean for food

Within the plankton, itself, holoplankton are those organisms that spend their entire life cycle as part of the plankton (e. Holoplankton are organisms that are planktonic for their entire life cycle A life cycle is a period involving 1 Generation of an Organism through means of Reproduction, whether through Asexual reproduction or Sexual g. most algae, copepods, salps, and some jellyfish). Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms Copepods are a group of small Crustaceans found in the sea and nearly every freshwater habitat and they constitute the biggest source of protein in the oceans A salp (plural salps; also salpa, plural salpae or salpas) is a barrel-shaped free-floating Tunicate. Jellyfish are free-swimming members of the phylum Cnidaria. They have several different basic morphologies that represent several different cnidarian classes including the By contrast, meroplankton are those organisms that are only planktonic for part of their lives (usually the larval stage), and then graduate to either the nekton or a benthic (sea floor) existence. Meroplankton are organisms that are planktonic for only a part of their life cycles usually the larval stage A larva ( Latin; plural larvae) is a juvenile form of Animal with indirect development, undergoing Metamorphosis (for example Benthos are the organisms which live on in or near the Seabed, also known as the Benthic zone. Examples of meroplankton include the larvae of sea urchins, starfish, crustaceans, marine worms, and most fish. Sea urchins are small globular spiny sea cat animals composing most of class Echinoidea. Starfish (also called sea stars) are any Echinoderms belonging to the class Asteroidea. Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting A worm is a common name given to a diverse group of invertebrate animals that have a long soft body and no legs Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two

Plankton abundance and distribution are strongly dependent on factors such as ambient nutrients concentrations, the physical state of the water column, and the abundance of other plankton. A nutrient is food or chemicals that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment

The study of plankton is termed planktology. Planktology is the study of Plankton, various Microorganisms that inhabit bodies of Water. Individual plankton are referred to as plankters.
Biologist Peter DeBoer describes plankton as "micro organisms, without which, nothing on earth would exist. Nothing. "

Functional groups

An amphipod (Hyperia macrocephala)

Plankton are primarily divided into broad functional (or trophic level) groups:

• Phytoplankton (from Greek phyton, or plant), autotrophic, prokaryotic or eukaryotic algae that live near the water surface where there is sufficient light to support photosynthesis. Amphipoda (amphipods are an order of animals that includes over 7000 described Species of Shrimp -like Crustaceans ranging from 1 mm to 140 mm In Ecology, trophic dynamics is the system of trophic levels ( Greek trophē, food which describe the position that an organism occupies Phytoplankton are the Autotrophic component of the Plankton community An autotroph (from the Greek autos = self and trophe = nutrition is an Organism that produces complex Organic compounds from simple The prokaryotes (proʊˈkærioʊts singular prokaryote /proʊˈkæriət/ are a group of Organisms that lack a Cell nucleus (= karyon or any other Animals Plants fungi, and Protists are eukaryotes (juːˈkærɪɒt or -oʊt Organisms whose cells are organized into complex Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. Among the more important groups are the diatoms, cyanobacteria and dinoflagellates. Diatoms ( Greek: (dia = "through" + (temnein = "to cut" i Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy The dinoflagellates are a large group of Flagellate Protists Most are marine Plankton, but
• Zooplankton (from Greek zoon, or animal), small protozoans or metazoans (e. Zooplankton are the Heterotrophic (sometimes detritivorous) type of Plankton. Protozoa (in Greek πρῶτον proton "first" and ζῷα zoia "animals" are unicellular Eukaryotes (singular g. crustaceans and other animals) that feed on other plankton and telonemia. Structure of crustaceans As Arthropods crustaceans have a stiff Exoskeleton, which must be shed to allow the animal to grow ( Ecdysis or molting Telonemia are a Phylum of microscopic Eukaryote, Single-celled organisms They are Protists and are suggested to have Evolutionary significance Some of the eggs and larvae of larger animals, such as fish, crustaceans, and annelids, are included here. In most Birds and Reptiles an egg ( Latin ovum) is the Zygote, resulting from Fertilization of the Ovum. A larva ( Latin; plural larvae) is a juvenile form of Animal with indirect development, undergoing Metamorphosis (for example The annelids, collectively called Annelida (from Latin anellus "little ring" are a large phylum of Animals comprising
• Bacterioplankton, bacteria and archaea, which play an important role in remineralising organic material down the water column (note that the prokaryotic phytoplankton are also bacterioplankton). Bacterioplankton refers to the bacterial component of the Plankton that drifts in the water column The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have In Biogeochemistry, remineralisation refers to the transformation of Organic molecules to Inorganic forms typically mediated by biological activity

This scheme divides the plankton community into broad producer, consumer and recycler groups. In reality, the trophic level of some plankton is not straightforward. For example, although most dinoflagellates are either photosynthetic producers or heterotrophic consumers, many species are mixotrophic depending upon their circumstances. A mixotrophic organism is one that obtains its electrons from an inorganic electron source ( Hydrogen-sulfide, Ammonium, Hydrogen) but uses organic matter

Size groups

Siphonophora – the "conveyor belt" of the upgrowing larvae and the ovarium can be seen

Plankton are also often described in terms of size. ^[2] Usually the following divisions are used:

However, some of these terms may be used with very different boundaries, especially on the larger end of the scale. A virus (from the Latin virus meaning Toxin or Poison) is a sub-microscopic infectious agent that is unable 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 proportion of all plankton in number and diversity. Year 1980 ( MCMLXXX) was a Leap year starting on Tuesday (link displays the 1980 Gregorian calendar)

Distribution

An amphipod

Plankton are found throughout the oceans, seas and lakes of Earth. Amphipoda (amphipods are an order of animals that includes over 7000 described Species of Shrimp -like Crustaceans ranging from 1 mm to 140 mm However, the local abundance of plankton varies horizontally, vertically and seasonally. The primary source of this variability is the availability of light. All plankton ecosystems are driven by the input of solar energy (but see chemosynthesis), and this confines primary production to surface waters, and to geographical regions and seasons when light is abundant. Chemosynthesis is the biological conversion of one or more carbon molecules (usually Carbon dioxide or Methane) and nutrients into organic matter using the Oxidation

A secondary source of variability is that of nutrient availability. Although large areas of the tropical and sub-tropical oceans have abundant light, they experience relatively low primary production because of the poor availability of nutrients such as nitrate, phosphate and silicate. The Tropics are centered on the Equator and limited in Latitude by the Tropic of Cancer in the northern hemisphere at approximately 23°26' (23 The subtropics are the zones of the Earth immediately north and south of the tropic zone which is bounded by the Tropic of Cancer and the Tropic of In Inorganic chemistry, a nitrate is a salt of Nitric acid with an Ion composed of one Nitrogen and three Oxygen atoms A phosphate, an Inorganic chemical, is a salt of Phosphoric acid. For the Artificial intelligence Androids of the 1990s Science fiction series Space Above and Beyond, see Silicate (AI This is a product of large-scale ocean circulation and stratification of the water column. An ocean current is continuous directed movement of Ocean water. In such regions, primary production, still usually occurs at greater depth, although at a reduced level (because of reduced light).

Despite significant concentrations of macronutrients, some regions of the ocean are unproductive (so-called HNLC regions)^[3]. HNLC stands for "high-nutrient low-chlorophyll" - a term used in marine ecology to describe areas of the ocean where the number of Phytoplankton (standing stock are Field studies have found that the mineral micronutrient iron is deficient in these regions, and that adding it can lead to the formation of blooms of many (though not all) kinds of phytoplankton^[4]. Micronutrients are Nutrients needed for life in small quantities Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 An algal bloom is a rapid increase in the population of Algae in an aquatic system Iron primarily reaches the ocean through the deposition of atmospheric dust on the sea surface. Paradoxically, oceanic areas adjacent to unproductive, arid regions of continents thus typically have abundant phytoplankton (e. In general terms the Climate of a local or region is said to be arid when it is characterized by a severe lack of available Water, to the extent of hindering g. , the western Atlantic Ocean, where trade winds bring dust from the Sahara Desert in north Africa). The trade winds (also called trades) are the prevailing pattern of easterly winds found in the Tropics near the Earth's Equator. The Sahara (الصحراء الكبرى aṣ-ṣaḥrā´ al-kubra, "The Great Desert" is the world's largest hot Desert and the world's second largest It has been suggested that large-scale "seeding" of the world's oceans with iron could generate blooms of phytoplankton large enough to draw down enough carbon dioxide out of the atmosphere to offset its anthropogenic emissions (responsible for global warming), although other researchers have disputed the scale of this effect^[5]. Iron fertilization is the intentional introduction of Iron, an essential Nutrient, to the upper Ocean to stimulate the marine Food chain Global warming is the increase in the average measured temperature of the

While plankton are found in the greatest abundance in surface waters, they occur throughout the water column. At depths where no primary production occurs, zooplankton and bacterioplankton instead make use of organic material sinking from the more productive surface waters above. This flux of sinking material can be especially high following the termination of spring blooms. The spring bloom is a sudden and strong bloom of Phytoplankton such as Diatoms or Dinoflagellates in the spring in temperate and sub-polar bodies of water

Biogeochemical significance

A copepod (Calanoida sp. Copepods are a group of small Crustaceans found in the sea and nearly every freshwater habitat and they constitute the biggest source of protein in the oceans ) ca. 1-2 mm long

Aside from representing the bottom few levels of a food chain that leads up to commercially important fisheries, plankton ecosystems play a role in the biogeochemical cycles of many important chemical elements. To help compare different Orders of magnitude this page lists Lengths between 10&minus3 m and 10&minus2 m (1 mm and 1 cm Food chains, also called food networks and/or trophic networks, describe the feeding relationships between species within an Ecosystem. Commerce is a division of trade or production which deals with the exchange of goods and services from producer to final consumer For the fishing industry and the practice of fishing see Fishing. An ecosystem is a natural unit consisting of all plants animals and micro-organisms( Biotic factors in an area functioning together with all of the non-living physical ( In Ecology and Earth science, a biogeochemical cycle is a circuit or pathway by which a Chemical element or Molecule moves through both biotic A chemical element is a type of Atom that is distinguished by its Atomic number; that is by the number of Protons in its nucleus. Of particular contemporary significance is their role in the ocean's carbon cycle. The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the Biosphere, Pedosphere, Geosphere, Hydrosphere, and

As stated, phytoplankton fix carbon in sunlit surface waters via photosynthesis. Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 Through (primarily) zooplankton grazing, this carbon enters the planktonic foodweb, where it is either respired to provide metabolic energy, or accumulates as biomass or detritus. Cellular respiration is the set of the metabolic reactions and processes that take place in Organisms cells to convert biochemical energy from Metabolism is the set of Chemical reactions that occur in living Organisms in order to maintain Life. Biomass, in Ecology, is the mass of living biological organisms in a given area or Ecosystem at a given time In Biology, detritus is non-living particulate organic material (as opposed to dissolved organic material As living or dead organic material is typically more dense than seawater it tends to sink, and in open ocean ecosystems away from the coasts this leads to the transport of carbon from surface waters to the deep. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different Seawater is Water from a Sea or Ocean. On average seawater in the world's oceans has a Salinity of about 3 The coast is defined as the part of the land adjoining or near the Ocean. This process is known as the biological pump, and is one of the reasons that the oceans constitute the largest (active) pool of carbon on Earth. In Oceanic Biogeochemistry, the biological pump is the sum of a suite of biologically-mediated processes that transport Carbon from the surface Earth science (also known as geoscience, the geosciences or the Earth Sciences) is an all-embracing term for the Sciences related to the planet

Some researchers have even proposed that it might be possible to increase the ocean's uptake of carbon dioxide generated through human activities by increasing the production of plankton through fertilization, primarily with the micronutrient iron. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Anthropogenic effects processes objects or materials are those that are derived from Human activities as opposed to those occurring in Natural environments without For soil improvement see Fertilization (soil. Micronutrients are Nutrients needed for life in small quantities Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 However, it is debatable whether this technique is practical at a large scale, and some researchers have drawn attention to possible drawbacks such as ocean anoxia and resultant methanogenesis (caused by the excess production remineralising at depth). Anoxic sea water is sea water depleted of Oxygen. It is generally found in areas with restricted water exchange Methanogens are Archaea that produce Methane as a Metabolic byproduct in Anoxic conditions In Biogeochemistry, remineralisation refers to the transformation of Organic molecules to Inorganic forms typically mediated by biological activity ^[6]

Importance to fish

Sea foam is produced by plankton

Zooplankton are initially the sole prey item for almost all fish larvae as they use up their yolk sacs and switch to external feeding for nutrition. This article is about the body of water For other uses see SEA and Seas. The most general definition of foam is a substance that is formed by trapping many gas Bubbles in a Liquid or Solid. Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two A larva ( Latin; plural larvae) is a juvenile form of Animal with indirect development, undergoing Metamorphosis (for example Fish species rely on the density and distribution of zooplankton to coincide with first-feeding larvae for good survival of larvae, which can otherwise starve. Natural factors (e. g. variations in oceanic currents) and man-made factors (e. g. dams on rivers) can strongly affect zooplankton density and distribution, which can in turn strongly affect the larval survival, and therefore breeding success and stock strength, of fish species.

See also

• Algal bloom
• Biological pump
• Gelatinous zooplankton
• Iron fertilization
• Nekton
• Ocean acidification
• Paradox of the plankton
• Primary production

References

External links

• Plankton*Net, taxonomic database of images of plankton species