Zooplankton are the heterotrophic component of the planktonic community (the " zoo- " prefix comes from Ancient Greek : ζῷον , romanized : zôion , lit. 'animal'), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequently, they drift or are carried along by currents in the ocean , or by currents in seas , lakes or rivers .
121-530: The smallmouth bass ( Micropterus dolomieu ) is a species of freshwater fish in the sunfish family ( Centrarchidae ) of the order Perciformes . It is the type species of its genus Micropterus ( black basses ), and is a popular game fish sought by anglers throughout the temperate zones of North America , and has been spread by stocking —as well as illegal introductions—to many cool-water tributaries and lakes in Canada and more so introduced in
242-556: A cell wall , as found in plants and many algae . Although the traditional practice of grouping protozoa with animals is no longer considered valid, the term continues to be used in a loose way to identify single-celled organisms that can move independently and feed by heterotrophy . Marine protozoans include zooflagellates , foraminiferans , radiolarians and some dinoflagellates . Radiolarians are unicellular predatory protists encased in elaborate globular shells usually made of silica and pierced with holes. Their name comes from
363-423: A mutation–selection balance . It is predicted that a viral quasispecies at a low but evolutionarily neutral and highly connected (that is, flat) region in the fitness landscape will outcompete a quasispecies located at a higher but narrower fitness peak in which the surrounding mutants are unfit, "the quasispecies effect" or the "survival of the flattest". There is no suggestion that a viral quasispecies resembles
484-400: A "classical" method of determining species, such as with Linnaeus, early in evolutionary theory. However, different phenotypes are not necessarily different species (e.g. a four-winged Drosophila born to a two-winged mother is not a different species). Species named in this manner are called morphospecies . In the 1970s, Robert R. Sokal , Theodore J. Crovello and Peter Sneath proposed
605-424: A 'smallest clade' idea" (a phylogenetic species concept). Mishler and Wilkins and others concur with this approach, even though this would raise difficulties in biological nomenclature. Wilkins cited the ichthyologist Charles Tate Regan 's early 20th century remark that "a species is whatever a suitably qualified biologist chooses to call a species". Wilkins noted that the philosopher Philip Kitcher called this
726-454: A better, more exciting fight than any other black bass . Rods are usually of ultralight to medium-heavy action. They may also be caught with a fly rod using a dry or wet artificial fly , nymphs, streamers, or imitations of larger aquatic creatures, such as hellgrammites , crawfish, or leeches. Floating topwater popper fly patterns and buzz baits are also popular for smallmouth fishing. For river fishing, spinning tackle or fly tackle has been
847-668: A central role in determining the magnitude of ectothermic temperature-size responses, but it is hard to disentangle the relative effects of oxygen and temperature from field data because these two variables are often strongly inter-related in the surface ocean. Zooplankton can be broken down into size classes which are diverse in their morphology, diet, feeding strategies, etc. both within classes and between classes: Microzooplankton are defined as heterotrophic and mixotrophic plankton. They primarily consist of phagotrophic protists , including ciliates, dinoflagellates, and mesozooplankton nauplii . Microzooplankton are major grazers of
968-428: A connected series of neighbouring populations, each of which can sexually interbreed with adjacent related populations, but for which there exist at least two "end" populations in the series, which are too distantly related to interbreed, though there is a potential gene flow between each "linked" population. Such non-breeding, though genetically connected, "end" populations may co-exist in the same region thus closing
1089-643: A critical role in supporting the ocean's biological pump through various forms of carbon export , including the production of fecal pellets, mucous feeding webs, molts, and carcasses. Fecal pellets are estimated to be a large contributor to this export, with copepod size rather than abundance expected to determine how much carbon actually reaches the ocean floor. The importance of fecal pellets can vary both by time and location. For example, zooplankton bloom events can produce larger quantities of fecal pellets, resulting in greater measures of carbon export. Additionally, as fecal pellets sink, they are reworked by microbes in
1210-432: A different species from its ancestors. Viruses have enormous populations, are doubtfully living since they consist of little more than a string of DNA or RNA in a protein coat, and mutate rapidly. All of these factors make conventional species concepts largely inapplicable. A viral quasispecies is a group of genotypes related by similar mutations, competing within a highly mutagenic environment, and hence governed by
1331-885: A focused effort be placed on the development of instrumentation that can link changes in phytoplankton biomass or optical properties with grazing. Grazing is a central, rate-setting process in ocean ecosystems and a driver of marine biogeochemical cycling . In all ocean ecosystems, grazing by heterotrophic protists constitutes the single largest loss factor of marine primary production and alters particle size distributions. Grazing affects all pathways of export production, rendering grazing important both for surface and deep carbon processes. Predicting central paradigms of ocean ecosystem function, including responses to environmental change requires accurate representation of grazing in global biogeochemical, ecosystem and cross-biome-comparison models. Several large-scale analyses have concluded that phytoplankton losses, which are dominated by grazing are
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#17327725743141452-617: A gel matrix, which can increase massively in size during blooms . As a result, Phaeocystis is an important contributor to the marine carbon and sulfur cycles . A number of forams are mixotrophic. These have unicellular algae as endosymbionts , from diverse lineages such as the green algae , red algae , golden algae , diatoms , and dinoflagellates . Mixotrophic foraminifers are particularly common in nutrient-poor oceanic waters. Some forams are kleptoplastic , retaining chloroplasts from ingested algae to conduct photosynthesis . By trophic orientation, dinoflagellates are all over
1573-508: A genetic boundary suitable for defining a species concept is present. DNA barcoding has been proposed as a way to distinguish species suitable even for non-specialists to use. One of the barcodes is a region of mitochondrial DNA within the gene for cytochrome c oxidase . A database, Barcode of Life Data System , contains DNA barcode sequences from over 190,000 species. However, scientists such as Rob DeSalle have expressed concern that classical taxonomy and DNA barcoding, which they consider
1694-729: A geographical region, so are zooplankton. However, species of zooplankton are not dispersed uniformly or randomly within a region of the ocean. As with phytoplankton, 'patches' of zooplankton species exist throughout the ocean. Though few physical barriers exist above the mesopelagic , specific species of zooplankton are strictly restricted by salinity and temperature gradients, while other species can withstand wide temperature and salinity gradients. Zooplankton patchiness can also be influenced by biological factors, as well as other physical factors. Biological factors include breeding, predation, concentration of phytoplankton, and vertical migration. The physical factor that influences zooplankton distribution
1815-409: A healthy environment, though they are still much more resilient than most trout species. Carnivorous, its diet comprises crayfish , amphibians , insects , and smaller fish, while the larvae feed on various zooplankton and insect larvae. Adults also cannibalize young of other parents. The female can lay up to 21,100 eggs, which are guarded by the male in his nest. When the weather gets colder, and
1936-511: A light yellow-brown and are more oval-shaped. There are two recognized subspecies, the Northern smallmouth bass ( M. dolomieui dolomieui ) and the Neosho smallmouth bass ( M. dolomieui velox ). The Northern smallmouth bass is much more widespread than the much smaller subgroup called the Neosho smallmouth bass. The Neosho are native to an ecologically isolated region of the lower Midwest known as
2057-465: A lineage should be divided into multiple chronospecies , or when populations have diverged to have enough distinct character states to be described as cladistic species. Species and higher taxa were seen from the time of Aristotle until the 18th century as categories that could be arranged in a hierarchy, the great chain of being . In the 19th century, biologists grasped that species could evolve given sufficient time. Charles Darwin 's 1859 book On
2178-556: A loss of river habitat caused by damming many formerly wild rivers to form lakes or reservoirs. In recent years, a renewed emphasis on preserving water quality and riparian habitat in the nation's rivers and lakes, together with stricter management practices, eventually benefited smallmouth populations and has caused a resurgence in their popularity with anglers. Today, smallmouth bass are very popular game fish , frequently sought by anglers using conventional spinning and bait casting gear, as well as fly fishing tackle. The smallmouth bass
2299-612: A lot about past environments and climates. Dinoflagellates are a phylum of unicellular flagellates with about 2,000 marine species. Some dinoflagellates are predatory , and thus belong to the zooplankton community. Their name comes from the Greek "dinos" meaning whirling and the Latin "flagellum" meaning a whip or lash . This refers to the two whip-like attachments (flagella) used for forward movement. Most dinoflagellates are protected with red-brown, cellulose armour. Excavates may be
2420-492: A misnomer, need to be reconciled, as they delimit species differently. Genetic introgression mediated by endosymbionts and other vectors can further make barcodes ineffective in the identification of species. A phylogenetic or cladistic species is "the smallest aggregation of populations (sexual) or lineages (asexual) diagnosable by a unique combination of character states in comparable individuals (semaphoronts)". The empirical basis – observed character states – provides
2541-541: A mix of internal plastids and external sources. Many marine microzooplankton are mixotrophic, which means they could also be classified as phytoplankton. Zooplankton ( / ˈ z oʊ . ə p l æ ŋ k t ən / ; / ˌ z oʊ . ə ˈ p l æ ŋ k t ən / ) are heterotrophic (sometimes detritivorous ) plankton . The word zooplankton is derived from Ancient Greek : ζῷον , romanized : zôion , lit. 'animal'; and πλᾰγκτός , planktós , 'wanderer; drifter'. Zooplankton
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#17327725743142662-449: A particular species, including which genus (and higher taxa) it is placed in, is a hypothesis about the evolutionary relationships and distinguishability of that group of organisms. As further information comes to hand, the hypothesis may be corroborated or refuted. Sometimes, especially in the past when communication was more difficult, taxonomists working in isolation have given two distinct names to individual organisms later identified as
2783-400: A perfect model of life, it is still a useful tool to scientists and conservationists for studying life on Earth, regardless of the theoretical difficulties. If species were fixed and clearly distinct from one another, there would be no problem, but evolutionary processes cause species to change. This obliges taxonomists to decide, for example, when enough change has occurred to declare that
2904-409: A result, zooplankton are primarily found in surface waters where food resources (phytoplankton or other zooplankton) are abundant. Zooplankton can also act as a disease reservoir . Crustacean zooplankton have been found to house the bacterium Vibrio cholerae , which causes cholera , by allowing the cholera vibrios to attach to their chitinous exoskeletons . This symbiotic relationship enhances
3025-905: A result, zooplankton must acquire nutrients by feeding on other organisms such as phytoplankton, which are generally smaller than zooplankton. Most zooplankton are microscopic but some (such as jellyfish ) are macroscopic , meaning they can be seen with the naked eye . Many protozoans (single-celled protists that prey on other microscopic life) are zooplankton, including zooflagellates , foraminiferans , radiolarians , some dinoflagellates and marine microanimals . Macroscopic zooplankton include pelagic cnidarians , ctenophores , molluscs , arthropods and tunicates , as well as planktonic arrow worms and bristle worms . The distinction between autotrophy and heterotrophy often breaks down in very small organisms. Recent studies of marine microplankton have indicated over half of microscopic plankton are mixotrophs , which can obtain energy and carbon from
3146-400: A short way of saying that something applies to many species within a genus, but not to all. If scientists mean that something applies to all species within a genus, they use the genus name without the specific name or epithet. The names of genera and species are usually printed in italics . However, abbreviations such as "sp." should not be italicised. When a species' identity is not clear,
3267-501: A slender but muscular fusiform body shape making them powerful swimmers. The coloration of the smallmouth bass' ctenoid scales range from golden-olive to dark brown dorsally which fades to a yellowish white ventrally with dark brown vertical bars or blotches along the body and dark brown horizontal bars on the head. The combination of the muscular fusiform body shape and camouflage like coloring make these fish highly effective ambush predators. The coloration can vary greatly depending on
3388-404: A specialist may use "cf." before the epithet to indicate that confirmation is required. The abbreviations "nr." (near) or "aff." (affine) may be used when the identity is unclear but when the species appears to be similar to the species mentioned after. With the rise of online databases, codes have been devised to provide identifiers for species that are already defined, including: The naming of
3509-523: A species as groups of actually or potentially interbreeding natural populations, which are reproductively isolated from other such groups. It has been argued that this definition is a natural consequence of the effect of sexual reproduction on the dynamics of natural selection. Mayr's use of the adjective "potentially" has been a point of debate; some interpretations exclude unusual or artificial matings that occur only in captivity, or that involve animals capable of mating but that do not normally do so in
3630-400: A species as determined by a taxonomist. A typological species is a group of organisms in which individuals conform to certain fixed properties (a type), so that even pre-literate people often recognise the same taxon as do modern taxonomists. The clusters of variations or phenotypes within specimens (such as longer or shorter tails) would differentiate the species. This method was used as
3751-491: A species. All species definitions assume that an organism acquires its genes from one or two parents very like the "daughter" organism, but that is not what happens in HGT. There is strong evidence of HGT between very dissimilar groups of prokaryotes , and at least occasionally between dissimilar groups of eukaryotes , including some crustaceans and echinoderms . The evolutionary biologist James Mallet concludes that there
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3872-685: A species. Generally the term includes the unknown element of a distinct act of creation. Many authors have argued that a simple textbook definition, following Mayr's concept, works well for most multi-celled organisms , but breaks down in several situations: Species identification is made difficult by discordance between molecular and morphological investigations; these can be categorised as two types: (i) one morphology, multiple lineages (e.g. morphological convergence , cryptic species ) and (ii) one lineage, multiple morphologies (e.g. phenotypic plasticity , multiple life-cycle stages). In addition, horizontal gene transfer (HGT) makes it difficult to define
3993-528: A taxonomic decision at the discretion of cognizant specialists, is not governed by the Codes of Zoological or Botanical Nomenclature, in contrast to the PhyloCode , and contrary to what is done in several other fields, in which the definitions of technical terms, like geochronological units and geopolitical entities, are explicitly delimited. The nomenclatural codes that guide the naming of species, including
4114-517: A traditional biological species. The International Committee on Taxonomy of Viruses has since 1962 developed a universal taxonomic scheme for viruses; this has stabilised viral taxonomy. Most modern textbooks make use of Ernst Mayr 's 1942 definition, known as the Biological Species Concept as a basis for further discussion on the definition of species. It is also called a reproductive or isolation concept. This defines
4235-447: A variation on the morphological species concept, a phenetic species, defined as a set of organisms with a similar phenotype to each other, but a different phenotype from other sets of organisms. It differs from the morphological species concept in including a numerical measure of distance or similarity to cluster entities based on multivariate comparisons of a reasonably large number of phenotypic traits. A mate-recognition species
4356-515: A variety of reasons. Viruses are a special case, driven by a balance of mutation and selection , and can be treated as quasispecies . Biologists and taxonomists have made many attempts to define species, beginning from morphology and moving towards genetics . Early taxonomists such as Linnaeus had no option but to describe what they saw: this was later formalised as the typological or morphological species concept. Ernst Mayr emphasised reproductive isolation, but this, like other species concepts,
4477-408: A year, meaning they respond to climate changes between years. Sparse, monthly sampling will still indicate vacillations. Protozoans are protists that feed on organic matter such as other microorganisms or organic tissues and debris. Historically, the protozoa were regarded as "one-celled animals", because they often possess animal -like behaviours, such as motility and predation , and lack
4598-438: Is "an entity composed of organisms which maintains its identity from other such entities through time and over space, and which has its own independent evolutionary fate and historical tendencies". This differs from the biological species concept in embodying persistence over time. Wiley and Mayden stated that they see the evolutionary species concept as "identical" to Willi Hennig 's species-as-lineages concept, and asserted that
4719-600: Is a categorization spanning a range of organism sizes including small protozoans and large metazoans . It includes holoplanktonic organisms whose complete life cycle lies within the plankton, as well as meroplanktonic organisms that spend part of their lives in the plankton before graduating to either the nekton or a sessile , benthic existence. Although zooplankton are primarily transported by ambient water currents, many have locomotion , used to avoid predators (as in diel vertical migration ) or to increase prey encounter rate. Just as any species can be limited within
4840-400: Is a group of sexually reproducing organisms that recognise one another as potential mates. Expanding on this to allow for post-mating isolation, a cohesion species is the most inclusive population of individuals having the potential for phenotypic cohesion through intrinsic cohesion mechanisms; no matter whether populations can hybridise successfully, they are still distinct cohesion species if
4961-458: Is a set of organisms adapted to a particular set of resources, called a niche, in the environment. According to this concept, populations form the discrete phenetic clusters that we recognise as species because the ecological and evolutionary processes controlling how resources are divided up tend to produce those clusters. A genetic species as defined by Robert Baker and Robert Bradley is a set of genetically isolated interbreeding populations. This
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5082-406: Is being exported via zooplankton fecal pellet production. Carcasses are also gaining recognition as being important contributors to carbon export. Jelly falls – the mass sinking of gelatinous zooplankton carcasses – occur across the world as a result of large blooms. Because of their large size, these gelatinous zooplankton are expected to hold a larger carbon content, making their sinking carcasses
5203-414: Is called speciation . Charles Darwin was the first to describe the role of natural selection in speciation in his 1859 book The Origin of Species . Speciation depends on a measure of reproductive isolation , a reduced gene flow. This occurs most easily in allopatric speciation, where populations are separated geographically and can diverge gradually as mutations accumulate. Reproductive isolation
5324-412: Is called the specific name or the specific epithet (in botanical nomenclature , also sometimes in zoological nomenclature ). For example, Boa constrictor is one of the species of the genus Boa , with constrictor being the species' epithet. While the definitions given above may seem adequate at first glance, when looked at more closely they represent problematic species concepts. For example,
5445-403: Is described formally, in a publication that assigns it a unique scientific name. The description typically provides means for identifying the new species, which may not be based solely on morphology (see cryptic species ), differentiating it from other previously described and related or confusable species and provides a validly published name (in botany) or an available name (in zoology) when
5566-658: Is evidence from DNA analysis that dinoflagellate symbiosis with radiolarians evolved independently from other dinoflagellate symbioses, such as with foraminifera . A mixotroph is an organism that can use a mix of different sources of energy and carbon , instead of having a single trophic mode on the continuum from complete autotrophy at one end to heterotrophy at the other. It is estimated that mixotrophs comprise more than half of all microscopic plankton. There are two types of eukaryotic mixotrophs: those with their own chloroplasts , and those with endosymbionts —and others that acquire them through kleptoplasty or by enslaving
5687-671: Is further weakened by the existence of microspecies , groups of organisms, including many plants, with very little genetic variability, usually forming species aggregates . For example, the dandelion Taraxacum officinale and the blackberry Rubus fruticosus are aggregates with many microspecies—perhaps 400 in the case of the blackberry and over 200 in the dandelion, complicated by hybridisation , apomixis and polyploidy , making gene flow between populations difficult to determine, and their taxonomy debatable. Species complexes occur in insects such as Heliconius butterflies, vertebrates such as Hypsiboas treefrogs, and fungi such as
5808-726: Is hard or even impossible to test. Later biologists have tried to refine Mayr's definition with the recognition and cohesion concepts, among others. Many of the concepts are quite similar or overlap, so they are not easy to count: the biologist R. L. Mayden recorded about 24 concepts, and the philosopher of science John Wilkins counted 26. Wilkins further grouped the species concepts into seven basic kinds of concepts: (1) agamospecies for asexual organisms (2) biospecies for reproductively isolated sexual organisms (3) ecospecies based on ecological niches (4) evolutionary species based on lineage (5) genetic species based on gene pool (6) morphospecies based on form or phenotype and (7) taxonomic species,
5929-573: Is heavily dependent on latitudinal location. Smallmouth require clean stone, rock, or gravel substrate for a successful spawn. In the United States, smallmouth bass were first introduced outside of their native range with the construction of the Erie Canal in 1825, extending the fish's range into central New York state. During the mid-to-late 19th century, smallmouth were transplanted via the nation's rail system to lakes and rivers throughout
6050-514: Is loss from zooplankton in the form of respired CO 2 . The relative sizes of zooplankton and prey also mediate how much carbon is released via sloppy feeding. Smaller prey are ingested whole, whereas larger prey may be fed on more “sloppily”, that is more biomatter is released through inefficient consumption. There is also evidence that diet composition can impact nutrient release, with carnivorous diets releasing more dissolved organic carbon (DOC) and ammonium than omnivorous diets. Zooplankton play
6171-403: Is no easy way to tell whether related geographic or temporal forms belong to the same or different species. Species gaps can be verified only locally and at a point of time. One is forced to admit that Darwin's insight is correct: any local reality or integrity of species is greatly reduced over large geographic ranges and time periods. The botanist Brent Mishler argued that the species concept
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#17327725743146292-478: Is not valid, notably because gene flux decreases gradually rather than in discrete steps, which hampers objective delimitation of species. Indeed, complex and unstable patterns of gene flux have been observed in cichlid teleosts of the East African Great Lakes . Wilkins argued that "if we were being true to evolution and the consequent phylogenetic approach to taxa, we should replace it with
6413-543: Is potentially the toughest fighting freshwater fish in North America, and is commonly the targeted species in many fresh water fishing tournaments. In addition to wild populations, the smallmouth bass is stocked in cool rivers and lakes throughout Canada and the United States. In shallow streams, it is a wary fish, though usually not to the extent of most trout. The smallmouth is highly regarded for its topwater fighting ability when hooked – old fishing journals referred to
6534-402: Is recycled back to the marine environment. Low feeding rates typically lead to high AE and small, dense pellets, while high feeding rates typically lead to low AE and larger pellets with more organic content. Another contributing factor to DOM release is respiration rate. Physical factors such as oxygen availability, pH, and light conditions may affect overall oxygen consumption and how much carbon
6655-456: Is released from zooplankton individuals or populations. Absorption efficiency (AE) is the proportion of food absorbed by plankton that determines how available the consumed organic materials are in meeting the required physiological demands. Depending on the feeding rate and prey composition, variations in AE may lead to variations in fecal pellet production, and thus regulates how much organic material
6776-610: Is sensitive to changes in temperature due to the thermal dependence of physiological processes. The plankton is mainly composed of ectotherms which are organisms that do not generate sufficient metabolic heat to elevate their body temperature, so their metabolic processes depends on external temperature. Consequently, ectotherms grow more slowly and reach maturity at a larger body size in colder environments, which has long puzzled biologists because classic theories of life-history evolution predict smaller adult sizes in environments delaying growth. This pattern of body size variation, known as
6897-586: Is similar to Mayr's Biological Species Concept, but stresses genetic rather than reproductive isolation. In the 21st century, a genetic species could be established by comparing DNA sequences. Earlier, other methods were available, such as comparing karyotypes (sets of chromosomes ) and allozymes ( enzyme variants). An evolutionarily significant unit (ESU) or "wildlife species" is a population of organisms considered distinct for purposes of conservation. In palaeontology , with only comparative anatomy (morphology) and histology from fossils as evidence,
7018-471: Is sometimes an important source of genetic variation. Viruses can transfer genes between species. Bacteria can exchange plasmids with bacteria of other species, including some apparently distantly related ones in different phylogenetic domains , making analysis of their relationships difficult, and weakening the concept of a bacterial species. Zooplankton Zooplankton can be contrasted with phytoplankton ( cyanobacteria and microalgae ), which are
7139-594: Is threatened by hybridisation, but this can be selected against once a pair of populations have incompatible alleles of the same gene, as described in the Bateson–Dobzhansky–Muller model . A different mechanism, phyletic speciation, involves one lineage gradually changing over time into a new and distinct form (a chronospecies ), without increasing the number of resultant species. Horizontal gene transfer between organisms of different species, either through hybridisation , antigenic shift , or reassortment ,
7260-671: The Dale Hollow Reservoir , on the Kentucky/Tennessee border, in 1955. In conventional fishing, smallmouth may be successfully caught on a wide range of natural and artificial baits or lures, including crankbaits , hair jigs, plastic jerkbaits, artificial worms, spinnerbaits , and all types of soft plastic lures, including curly tail grubs or tubes with lead head jigs. Spinning reels or baitcasting reels may be used, with line strengths of 6 to 15 pounds typically utilized. According to many, smallmouth typically put up
7381-530: The ICZN for animals and the ICN for plants, do not make rules for defining the boundaries of the species. Research can change the boundaries, also known as circumscription, based on new evidence. Species may then need to be distinguished by the boundary definitions used, and in such cases the names may be qualified with sensu stricto ("in the narrow sense") to denote usage in the exact meaning given by an author such as
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#17327725743147502-666: The Portuguese Man o' War ; crustaceans such as cladocerans , copepods , ostracods , isopods , amphipods , mysids and krill ; chaetognaths (arrow worms); molluscs such as pteropods ; and chordates such as salps and juvenile fish. This wide phylogenetic range includes a similarly wide range in feeding behavior: filter feeding , predation and symbiosis with autotrophic phytoplankton as seen in corals. Zooplankton feed on bacterioplankton , phytoplankton, other zooplankton (sometimes cannibalistically ), detritus (or marine snow ) and even nektonic organisms . As
7623-399: The fly agaric . Natural hybridisation presents a challenge to the concept of a reproductively isolated species, as fertile hybrids permit gene flow between two populations. For example, the carrion crow Corvus corone and the hooded crow Corvus cornix appear and are classified as separate species, yet they can hybridise where their geographical ranges overlap. A ring species is
7744-507: The jaguar ( Panthera onca ) of Latin America or the leopard ( Panthera pardus ) of Africa and Asia. In contrast, the scientific names of species are chosen to be unique and universal (except for some inter-code homonyms ); they are in two parts used together : the genus as in Puma , and the specific epithet as in concolor . A species is given a taxonomic name when a type specimen
7865-563: The marine food web , gelatinous organisms with a body plan largely based on water that offers little nutritional value or interest for other organisms apart from a few specialised predators such as the ocean sunfish and the leatherback sea turtle . That view has recently been challenged. Jellyfish, and more gelatinous zooplankton in general, which include salps and ctenophores , are very diverse, fragile with no hard parts, difficult to see and monitor, subject to rapid population swings and often live inconveniently far from shore or deep in
7986-545: The oligotrophic waters of the open ocean. Through sloppy feeding, excretion, egestion, and leaching of fecal pellets , zooplankton release dissolved organic matter (DOM) which controls DOM cycling and supports the microbial loop . Absorption efficiency, respiration, and prey size all further complicate how zooplankton are able to transform and deliver carbon to the deep ocean . Excretion and sloppy feeding (the physical breakdown of food source) make up 80% and 20% of crustacean zooplankton-mediated DOM release respectively. In
8107-406: The "cynical species concept", and arguing that far from being cynical, it usefully leads to an empirical taxonomy for any given group, based on taxonomists' experience. Other biologists have gone further and argued that we should abandon species entirely, and refer to the "Least Inclusive Taxonomic Units" (LITUs), a view that would be coherent with current evolutionary theory. The species concept
8228-624: The Central Interior Highlands, which weave through southwestern Missouri, northern Arkansas and northeastern Oklahoma. They eat tadpoles , fish, aquatic insects, and crayfish . The world record size is 11 pounds 15 ounces (5.41 kg) caught in the Dale Hollow reservoir, on the Kentucky — Tennessee border. The smallmouth bass is found in clearer water than the largemouth, especially streams, rivers, and
8349-411: The Latin for "hole bearers". Their shells, often called tests , are chambered (forams add more chambers as they grow). The shells are usually made of calcite, but are sometimes made of agglutinated sediment particles or chiton , and (rarely) silica. Most forams are benthic, but about 40 species are planktic. They are widely researched with well-established fossil records which allow scientists to infer
8470-521: The Latin for "radius". They catch prey by extending parts of their body through the holes. As with the silica frustules of diatoms, radiolarian shells can sink to the ocean floor when radiolarians die and become preserved as part of the ocean sediment . These remains, as microfossils , provide valuable information about past oceanic conditions. Like radiolarians, foraminiferans ( forams for short) are single-celled predatory protists, also protected with shells that have holes in them. Their name comes from
8591-626: The Origin of Species explained how species could arise by natural selection . That understanding was greatly extended in the 20th century through genetics and population ecology . Genetic variability arises from mutations and recombination , while organisms themselves are mobile, leading to geographical isolation and genetic drift with varying selection pressures . Genes can sometimes be exchanged between species by horizontal gene transfer ; new species can arise rapidly through hybridisation and polyploidy ; and species may become extinct for
8712-642: The United States. The maximum recorded size is approximately 27 inches (69 cm) and 12 pounds (5.4 kg). The smallmouth bass is native to the upper and middle Mississippi River basin, the Saint Lawrence River – Great Lakes system, the Champlain Valley , and the Hudson Bay basin. Its common names include smallmouth , bronzeback , brown bass , brownie , smallie , bronze bass , and bareback bass . Smallmouth have
8833-405: The abbreviation "sp." in the singular or "spp." (standing for species pluralis , Latin for "multiple species") in the plural in place of the specific name or epithet (e.g. Canis sp.). This commonly occurs when authors are confident that some individuals belong to a particular genus but are not sure to which exact species they belong, as is common in paleontology . Authors may also use "spp." as
8954-570: The amount of hybridisation is insufficient to completely mix their respective gene pools . A further development of the recognition concept is provided by the biosemiotic concept of species. In microbiology , genes can move freely even between distantly related bacteria, possibly extending to the whole bacterial domain. As a rule of thumb, microbiologists have assumed that members of Bacteria or Archaea with 16S ribosomal RNA gene sequences more similar than 97% to each other need to be checked by DNA–DNA hybridisation to decide if they belong to
9075-436: The bacterium's ability to survive in an aquatic environment, as the exoskeleton provides the bacterium with carbon and nitrogen. Body size has been defined as a "master trait" for plankton as it is a morphological characteristic shared by organisms across taxonomy that characterises the functions performed by organisms in ecosystems. It has a paramount effect on growth, reproduction, feeding strategies and mortality. One of
9196-474: The biological species concept, "the several versions" of the phylogenetic species concept, and the idea that species are of the same kind as higher taxa are not suitable for biodiversity studies (with the intention of estimating the number of species accurately). They further suggested that the concept works for both asexual and sexually-reproducing species. A version of the concept is Kevin de Queiroz 's "General Lineage Concept of Species". An ecological species
9317-505: The biological species concept, a cladistic species does not rely on reproductive isolation – its criteria are independent of processes that are integral in other concepts. Therefore, it applies to asexual lineages. However, it does not always provide clear cut and intuitively satisfying boundaries between taxa, and may require multiple sources of evidence, such as more than one polymorphic locus, to give plausible results. An evolutionary species, suggested by George Gaylord Simpson in 1951,
9438-428: The boundaries between closely related species become unclear with hybridisation , in a species complex of hundreds of similar microspecies , and in a ring species . Also, among organisms that reproduce only asexually , the concept of a reproductive species breaks down, and each clone is potentially a microspecies. Although none of these are entirely satisfactory definitions, and while the concept of species may not be
9559-472: The ciliate abundance was mixotrophic, and up to 65% of the amoeboid, foram and radiolarian biomass was mixotrophic. Phaeocystis species are endosymbionts to acantharian radiolarians. Phaeocystis is an important algal genus found as part of the marine phytoplankton around the world. It has a polymorphic life cycle, ranging from free-living cells to large colonies. It has the ability to form floating colonies, where hundreds of cells are embedded in
9680-433: The concept of a chronospecies can be applied. During anagenesis (evolution, not necessarily involving branching), some palaeontologists seek to identify a sequence of species, each one derived from the phyletically extinct one before through continuous, slow and more or less uniform change. In such a time sequence, some palaeontologists assess how much change is required for a morphologically distinct form to be considered
9801-416: The concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. About 14% of these had been described by 2011. All species (except viruses ) are given a two-part name , called a "binomial". The first part of a binomial is the genus to which the species belongs. The second part
9922-493: The contribution of jellyfish to the energy budgets of predators may be much greater than assumed because of rapid digestion, low capture costs, availability, and selective feeding on the more energy-rich components. Feeding on jellyfish may make marine predators susceptible to ingestion of plastics." According to a 2017 study, narcomedusae consume the greatest diversity of mesopelagic prey, followed by physonect siphonophores , ctenophores and cephalopods . The importance of
10043-457: The cryptophytes by itself, and instead relies on ingesting ciliates such as the red Myrionecta rubra , which sequester their chloroplasts from a specific cryptophyte clade (Geminigera/Plagioselmis/Teleaulax)". Free-living species in the crustacean class Copepoda are typically 1 to 2 mm long with teardrop-shaped bodies. Like all crustaceans, their bodies are divided into three sections: head, thorax, and abdomen, with two pairs of antennae;
10164-450: The dilution technique, an elegant method of measuring microzooplankton herbivory rate, has been developed for almost four decades (Landry and Hassett 1982). The number of observations of microzooplankton herbivory rate is around 1600 globally, far less than that of primary productivity (> 50,000). This makes validating and optimizing the grazing function of microzooplankton difficult in ocean ecosystem models. Mesozooplankton are one of
10285-547: The entire phototrophic cell. The distinction between plants and animals often breaks down in very small organisms. Possible combinations are photo- and chemotrophy , litho- and organotrophy , auto- and heterotrophy or other combinations of these. Mixotrophs can be either eukaryotic or prokaryotic . They can take advantage of different environmental conditions. Many marine microzooplankton are mixotrophic, which means they could also be classified as phytoplankton. Recent studies of marine microzooplankton found 30–45% of
10406-435: The evidence to support hypotheses about evolutionarily divergent lineages that have maintained their hereditary integrity through time and space. Molecular markers may be used to determine diagnostic genetic differences in the nuclear or mitochondrial DNA of various species. For example, in a study done on fungi , studying the nucleotide characters using cladistic species produced the most accurate results in recognising
10527-496: The first pair is often long and prominent. They have a tough exoskeleton made of calcium carbonate and usually have a single red eye in the centre of their transparent head. About 13,000 species of copepods are known, of which about 10,200 are marine. They are usually among the more dominant members of the zooplankton. In addition to copepods the crustacean classes ostracods , branchiopods and malacostracans also have planktonic members. Barnacles are planktonic only during
10648-980: The fishes age, habitat, water quality, diet, and the spawning cycle. Generally, the protruding jaw of the smallmouth does not extend back beyond the eyes which are red or brown. They have two dorsal fins which are separated by a shallow interdorsal notch. The front dorsal has 9–11 spiney rays and the back dorsal has 13–15 soft rays. Males are generally smaller than females. The males tend to range around two pounds, while females can range from three to six pounds. Their average sizes and coloration can differ, depending on if they are found in lacustrine or riverine habitats. Smallmouth found in riverine habitats are generally long and slender which allows greater agility in moving water, while those found in lacustrine habitats and shorter and deeper bodied. Riverine smallmouth that live in dark water tend to be rather torpedo-shaped and very dark brown to be more efficient for feeding. Lacustrine smallmouth bass, however, that live in sandy areas, tend to be
10769-452: The larger size classes of zooplankton. In most regions, mesozooplankton are dominated by copepods , such as Calanus finmarchicus and Calanus helgolandicus . Mesozooplankton are an important prey for fish. As plankton are rarely fished, it has been argued that mesoplankton abundance and species composition can be used to study marine ecosystems' response to climate change. This is because they have life cycles that generally last less than
10890-461: The larval stage. Ichthyoplankton are the eggs and larvae of fish ("ichthyo" comes from the Greek word for fish ). They are planktonic because they cannot swim effectively under their own power, but must drift with the ocean currents. Fish eggs cannot swim at all, and are unambiguously planktonic. Early stage larvae swim poorly, but later stage larvae swim better and cease to be planktonic as they grow into juvenile fish . Fish larvae are part of
11011-418: The majority of organic carbon loss from marine primary production . However, zooplankton grazing remains one of the key unknowns in global predictive models of carbon flux, the marine food web structure and ecosystem characteristics, because empirical grazing measurements are sparse, resulting in poor parameterisation of grazing functions. To overcome this critical knowledge gap, it has been suggested that
11132-413: The most basal flagellate lineage. Dinoflagellates often live in symbiosis with other organisms. Many nassellarian radiolarians house dinoflagellate symbionts within their tests. The nassellarian provides ammonium and carbon dioxide for the dinoflagellate, while the dinoflagellate provides the nassellarian with a mucous membrane useful for hunting and protection against harmful invaders. There
11253-420: The most is mixing of the water column ( upwelling and downwelling along the coast and in the open ocean) that affects nutrient availability and, in turn, phytoplankton production. Through their consumption and processing of phytoplankton and other food sources, zooplankton play a role in aquatic food webs , as a resource for consumers on higher trophic levels (including fish), and as a conduit for packaging
11374-481: The most popular angling tools for smallmouth in North America for many years. When fishing in colder water, it is believed to be more effective to fish with smaller lures like hair jigs or small spinners. During the rest of the year, smallmouth are usually taken using soft plastic tubes or spinnerbaits. The best spots in rivers to fish for smallmouth are behind rocks or in eddies, where water swirls around. Smallmouth can also be taken in cool lakes like Lake Erie or any of
11495-541: The nation's eastern trout rivers were polluted or experienced elevated water temperatures, reducing the range of native brook trout . Smallmouth bass were often introduced to northern rivers with increased water temperatures and slowly became a popular gamefish with many anglers. Equally adaptable to large, cool-water impoundments and reservoirs, the smallmouth also spread far beyond its original native range. Later, smallmouth populations also began to decline after years of damage caused by overdevelopment and pollution, as well as
11616-574: The northern and western United States, as far as California. Shippers found that smallmouth bass were a hardy species that could be transported in buckets or barrels by rail, sometimes using the spigots from the railroad water tanks to aerate the fingerlings. They were introduced east of the Appalachians just before the Civil War, and afterwards transplanted to the states of New England. With increased industrialization and land use changes, many of
11737-523: The northern lakes. Species A species ( pl. : species) is a population of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring , typically by sexual reproduction . It is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity . Other ways of defining species include their karyotype , DNA sequence, morphology , behaviour, or ecological niche . In addition, paleontologists use
11858-483: The numerous fungi species of all the concepts studied. Versions of the phylogenetic species concept that emphasise monophyly or diagnosability may lead to splitting of existing species, for example in Bovidae , by recognising old subspecies as species, despite the fact that there are no reproductive barriers, and populations may intergrade morphologically. Others have called this approach taxonomic inflation , diluting
11979-440: The ocean. It is difficult for scientists to detect and analyse jellyfish in the guts of predators, since they turn to mush when eaten and are rapidly digested. But jellyfish bloom in vast numbers, and it has been shown they form major components in the diets of tuna , spearfish and swordfish as well as various birds and invertebrates such as octopus , sea cucumbers , crabs and amphipods . "Despite their low energy density,
12100-410: The oldest manifestations of the biogeography of traits was proposed over 170 years ago, namely Bergmann's rule , in which field observations showed that larger species tend to be found at higher, colder latitudes. In the oceans, size is critical in determining trophic links in planktonic ecosystems and is thus a critical factor in regulating the efficiency of the biological carbon pump . Body size
12221-531: The organic material in the biological pump . Since they are typically small, zooplankton can respond rapidly to increases in phytoplankton abundance, for instance, during the spring bloom . Zooplankton are also a key link in the biomagnification of pollutants such as mercury . Ecologically important protozoan zooplankton groups include the foraminiferans , radiolarians and dinoflagellates (the last of these are often mixotrophic ). Important metazoan zooplankton include cnidarians such as jellyfish and
12342-593: The paper is accepted for publication. The type material is usually held in a permanent repository, often the research collection of a major museum or university, that allows independent verification and the means to compare specimens. Describers of new species are asked to choose names that, in the words of the International Code of Zoological Nomenclature , are "appropriate, compact, euphonious, memorable, and do not cause offence". Books and articles sometimes intentionally do not identify species fully, using
12463-674: The person who named the species, while the antonym sensu lato ("in the broad sense") denotes a wider usage, for instance including other subspecies. Other abbreviations such as "auct." ("author"), and qualifiers such as "non" ("not") may be used to further clarify the sense in which the specified authors delineated or described the species. Species are subject to change, whether by evolving into new species, exchanging genes with other species, merging with other species or by becoming extinct. The evolutionary process by which biological populations of sexually-reproducing organisms evolve to become distinct or reproductively isolated as species
12584-566: The place. Some dinoflagellates are known to be photosynthetic , but a large fraction of these are in fact mixotrophic , combining photosynthesis with ingestion of prey ( phagotrophy ). Some species are endosymbionts of marine animals and other protists, and play an important part in the biology of coral reefs . Others predate other protozoa, and a few forms are parasitic. Many dinoflagellates are mixotrophic and could also be classified as phytoplankton. The toxic dinoflagellate Dinophysis acuta acquire chloroplasts from its prey. "It cannot catch
12705-642: The plankton community. As the primary consumers of marine phytoplankton, microzooplankton consume ~ 59–75% daily of the marine primary production , much larger than mesozooplankton. That said, macrozooplankton can sometimes have greater consumption rates in eutrophic ecosystems because the larger phytoplankton can be dominant there. Microzooplankton are also pivotal regenerators of nutrients which fuel primary production and food sources for metazoans. Despite their ecological importance, microzooplankton remain understudied. Routine oceanographic observations seldom monitor microzooplankton biomass or herbivory rate, although
12826-531: The plant-like component of the plankton community (the " phyto- " prefix comes from Ancient Greek: φῠτόν , romanized: phutón , lit. 'plant', although taxonomically not plants ). Zooplankton are heterotrophic (other-feeding), whereas phytoplankton are autotrophic (self-feeding), often generating biological energy and macromolecules through chlorophyllic carbon fixation using sunlight — in other words, zooplankton cannot manufacture their own food, while phytoplankton can. As
12947-417: The putative explanation for annual cycles in phytoplankton biomass, accumulation rates and export production. In addition to linking primary producers to higher trophic levels in marine food webs , zooplankton also play an important role as “recyclers” of carbon and other nutrients that significantly impact marine biogeochemical cycles , including the biological pump . This is particularly important in
13068-487: The result of misclassification leading to questions on whether there really are any ring species. The commonly used names for kinds of organisms are often ambiguous: "cat" could mean the domestic cat, Felis catus , or the cat family, Felidae . Another problem with common names is that they often vary from place to place, so that puma, cougar, catamount, panther, painter and mountain lion all mean Puma concolor in various parts of America, while "panther" may also mean
13189-586: The ring. Ring species thus present a difficulty for any species concept that relies on reproductive isolation. However, ring species are at best rare. Proposed examples include the herring gull – lesser black-backed gull complex around the North pole, the Ensatina eschscholtzii group of 19 populations of salamanders in America, and the greenish warbler in Asia, but many so-called ring species have turned out to be
13310-413: The rocky areas and stumps and also sandy bottoms of lakes and reservoirs. It can also survive in a stronger current than other black bass. The smallmouth prefers cooler water temperatures than its cousin the largemouth bass , and as a result will often seek out deeper, faster moving water during the hot summer months. Because it is intolerant of pollution , the smallmouth bass is a good natural indicator of
13431-508: The same species. This concept was narrowed in 2006 to a similarity of 98.7%. The average nucleotide identity (ANI) method quantifies genetic distance between entire genomes , using regions of about 10,000 base pairs . With enough data from genomes of one genus, algorithms can be used to categorize species, as for Pseudomonas avellanae in 2013, and for all sequenced bacteria and archaea since 2020. Observed ANI values among sequences appear to have an "ANI gap" at 85–95%, suggesting that
13552-529: The same species. When two species names are discovered to apply to the same species, the older species name is given priority and usually retained, and the newer name considered as a junior synonym, a process called synonymy . Dividing a taxon into multiple, often new, taxa is called splitting . Taxonomists are often referred to as "lumpers" or "splitters" by their colleagues, depending on their personal approach to recognising differences or commonalities between organisms. The circumscription of taxa, considered
13673-435: The same study, fecal pellet leaching was found to be an insignificant contributor. For protozoan grazers, DOM is released primarily through excretion and egestion and gelatinous zooplankton can also release DOM through the production of mucus. Leaching of fecal pellets can extend from hours to days after initial egestion and its effects can vary depending on food concentration and quality. Various factors can affect how much DOM
13794-409: The smallmouth bass as "ounce for ounce and pound for pound the gamest fish that swims". Smallmouth bass are not usually taken for the table, but rather are caught and released by most anglers. However, smaller specimens in cooler water often have higher quality filets of white, firm flesh when cooked. The current all-tackle world record for a smallmouth bass is 11 lb 15 oz, caught by David Hayes in
13915-455: The so-called "jelly web" is only beginning to be understood, but it seems medusae, ctenophores and siphonophores can be key predators in deep pelagic food webs with ecological impacts similar to predator fish and squid. Traditionally gelatinous predators were thought ineffectual providers of marine trophic pathways, but they appear to have substantial and integral roles in deep pelagic food webs . Grazing by single-celled zooplankton accounts for
14036-506: The species concept and making taxonomy unstable. Yet others defend this approach, considering "taxonomic inflation" pejorative and labelling the opposing view as "taxonomic conservatism"; claiming it is politically expedient to split species and recognise smaller populations at the species level, because this means they can more easily be included as endangered in the IUCN red list and can attract conservation legislation and funding. Unlike
14157-511: The temperature-size rule (TSR), has been observed for a wide range of ectotherms, including single-celled and multicellular species, invertebrates and vertebrates. The processes underlying the inverse relationship between body size and temperature remain to be identified. Despite temperature playing a major role in shaping latitudinal variations in organism size, these patterns may also rely on complex interactions between physical, chemical and biological factors. For instance, oxygen supply plays
14278-407: The water column, which can thus alter the carbon composition of the pellet. This affects how much carbon is recycled in the euphotic zone and how much reaches depth. Fecal pellet contribution to carbon export is likely underestimated; however, new advances in quantifying this production are currently being developed, including the use of isotopic signatures of amino acids to characterize how much carbon
14399-572: The water temperature drops below 15 C (60 F), smallmouth will often migrate in search of deeper pools in which they enter a semi-hibernation state, moving sluggishly and feeding very little until the warm season returns. The migration patterns of smallmouth have been tracked and it is not unusual for a smallmouth to travel 12 miles in a single day in a stream, creek or river. The overall migration can exceed 60 miles. Smallmouth generally begin spawning patterns in spring or early summer when water temperatures are between 15–18 °C (59.0–64.4 °F), which
14520-540: The wild. It is difficult to define a species in a way that applies to all organisms. The debate about species concepts is called the species problem. The problem was recognised even in 1859, when Darwin wrote in On the Origin of Species : I was much struck how entirely vague and arbitrary is the distinction between species and varieties. He went on to write: No one definition has satisfied all naturalists; yet every naturalist knows vaguely what he means when he speaks of
14641-413: The zooplankton that eat smaller plankton, while fish eggs carry their own food supply. Both eggs and larvae are themselves eaten by larger animals. Gelatinous zooplankton include ctenophores , medusae , salps , and Chaetognatha in coastal waters. Jellyfish are slow swimmers, and most species form part of the plankton. Traditionally jellyfish have been viewed as trophic dead ends, minor players in
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