Genus ( / ˈ dʒ iː n ə s / ; pl. : genera / ˈ dʒ ɛ n ər ə / ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses . In binomial nomenclature , the genus name forms the first part of the binomial species name for each species within the genus.
141-537: Alternate taxonomy: For genera , see below . Cichlids / ˈ s ɪ k l ɪ d z / are fish from the family Cichlidae in the order Cichliformes . Traditionally Cichlids were classed in a suborder, the Labroidei , along with the wrasses ( Labridae ), in the order Perciformes , but molecular studies have contradicted this grouping. On the basis of fossil evidence, it first appeared in Argentina during
282-452: A negative pressure in the mouth. Instead, when the moray bites prey, it first bites normally with its oral jaws, capturing the prey. Immediately thereafter, the pharyngeal jaws are brought forward and bite down on the prey to grip it; they then retract, pulling the prey down the moray eel's gullet, allowing it to be swallowed. All vertebrates have a pharynx, used in both feeding and respiration. The pharynx arises during development through
423-456: A few changes to the form of cranial bones, allow it to achieve extreme jaw protrusion. Pharyngeal jaws are a second set of jaws distinct from the primary (oral) jaws. They are contained within the throat, or pharynx , of most bony fish . They are believed to have originated, in a similar way to oral jaws, as a modification of the fifth gill arch which no longer has a respiratory function. The first four arches still function as gills. Unlike
564-407: A genus is determined by taxonomists . The standards for genus classification are not strictly codified, so different authorities often produce different classifications for genera. There are some general practices used, however, including the idea that a newly defined genus should fulfill these three criteria to be descriptively useful: Moreover, genera should be composed of phylogenetic units of
705-467: A group, cichlids exhibit a similar diversity of body shapes, ranging from strongly laterally compressed species (such as Altolamprologus , Pterophyllum , and Symphysodon ) to species that are cylindrical and highly elongated (such as Julidochromis , Teleogramma , Teleocichla , Crenicichla , and Gobiocichla ). Generally, however, cichlids tend to be of medium size, ovate in shape, and slightly laterally compressed, and generally similar to
846-567: A high speed of jaw opening, opening their jaws in 20 milliseconds and completing the whole process in 50-60 milliseconds, comparable to modern fishes that use suction feeding to assist in prey capture. They could also produce high bite forces when closing the jaw, estimated at 6,000 N (1,350 lb f ) at the tip and 7,400 N (1,660 lb f ) at the blade edge in the largest individuals. The pressures generated in those regions were high enough to puncture or cut through cuticle or dermal armour suggesting that Dunkleosteus terrelli
987-413: A large great white shark may have up to five layers. In the rostrum (snout), the cartilage can be spongy and flexible to absorb the power of impacts. In sharks and other extant elasmobranchs the upper jaw is not fused to the cranium , and the lower jaw is articulated with the upper. The arrangement of soft tissue and any additional articulations connecting these elements is collectively known as
1128-651: A later homonym of a validly published name is a nomen illegitimum or nom. illeg. ; for a full list refer to the International Code of Nomenclature for algae, fungi, and plants and the work cited above by Hawksworth, 2010. In place of the "valid taxon" in zoology, the nearest equivalent in botany is " correct name " or "current name" which can, again, differ or change with alternative taxonomic treatments or new information that results in previously accepted genera being combined or split. Prokaryote and virus codes of nomenclature also exist which serve as
1269-447: A layer of tiny hexagonal plates called " tesserae ", which are crystal blocks of calcium salts arranged as a mosaic . This gives these areas much of the same strength found in the bony tissue found in other animals. Generally sharks have only one layer of tesserae, but the jaws of large specimens, such as the bull shark , tiger shark , and the great white shark , have two to three layers or more, depending on body size. The jaws of
1410-628: A long time and redescribed as new by a range of subsequent workers, or if a range of genera previously considered separate taxa have subsequently been consolidated into one. For example, the World Register of Marine Species presently lists 8 genus-level synonyms for the sperm whale genus Physeter Linnaeus, 1758, and 13 for the bivalve genus Pecten O.F. Müller, 1776. Within the same kingdom, one generic name can apply to one genus only. However, many names have been assigned (usually unintentionally) to two or more different genera. For example,
1551-483: A male and female leads to courtship. Courtship in male cichlids follows the establishment of some form of territory, sometimes coupled with building a bower to attract mates. After this, males may attempt to attract female cichlids to their territories by a variety of lekking display strategies or otherwise seek out females of their species. However, cichlids, at the time of spawning, undergo a behavioral change such that they become less receptive to outside interactions. This
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#17327728529301692-600: A mating partner is unavailable. Pit spawning, also referred to as substrate breeding, is a behavior in cichlid fish in which a fish builds a pit in the sand or ground, where a pair court and consequently spawn. Many different factors go into this behavior of pit spawning, including female choice of the male and pit size, as well as the male defense of the pits once they are dug in the sand. Cichlids are often divided into two main groups: mouthbrooders and substrate brooders. Different parenting investment levels and behaviors are associated with each type of reproduction. As pit spawning
1833-480: A minor part of their diets. Other cichlids are detritivores and eat organic material, called Aufwuchs (offal); among these species are the tilapiines of the genera Oreochromis , Sarotherodon , and Tilapia . Other cichlids are predatory and eat little or no plant matter. These include generalists that catch a variety of small animals, including other fishes and insect larvae (e.g. Pterophyllum ), as well as variety of specialists. Trematocranus
1974-503: A mixed school of young have also been observed in multiple cichlid species, including Amphilophus citrinellus , Etroplus suratensis , and Tilapia rendalli . Comparably, the fry of Neolamprologus brichardi , a species that commonly lives in large groups, are protected not only by the adults, but also by older juveniles from previous spawns. Several cichlids, including discus ( Symphysodon spp.), some Amphilophus species, Etroplus , and Uaru species, feed their young with
2115-399: A more or less coherent skull roof in lungfish and holost fish. The simpler structure is found in jawless fish , in which the cranium is represented by a trough-like basket of cartilaginous elements only partially enclosing the brain, and associated with the capsules for the inner ears and the single nostril. Cartilaginous fish , such as sharks , also have simple skulls. The cranium
2256-485: A primary study species in fish-feeding biomechanics due to their jaw structure. They have protractile mouths, usually with separate jaw teeth that jut outwards. Many species can be readily recognized by their thick lips, the inside of which is sometimes curiously folded, a peculiarity which gave rise the German name of "lip-fishes" ( Lippfische ). The nasal and mandibular bones are connected at their posterior ends to
2397-409: A reference for designating currently accepted genus names as opposed to others which may be either reduced to synonymy, or, in the case of prokaryotes, relegated to a status of "names without standing in prokaryotic nomenclature". An available (zoological) or validly published (botanical) name that has been historically applied to a genus but is not regarded as the accepted (current/valid) name for
2538-439: A remarkably rapid change in coloration, during which a successfully dominant territorial male assumes a more vivid and brighter coloration, while a subordinate or "nonterritorial" male assumes a dull-pale coloration. In addition to color displays, cichlids employ their lateral lines to sense movements of water around their opponents to evaluate the competing male for physical traits/fitness. Male cichlids are very territorial due to
2679-463: A series of six or more outpocketings called pharyngeal arches on the lateral sides of the head. The pharyngeal arches give rise to a number of different structures in the skeletal, muscular and circulatory systems in a manner which varies across the vertebrates. Pharyngeal arches trace back through chordates to basal deuterostomes who also share endodermal outpocketings of the pharyngeal apparatus. Similar patterns of gene expression can be detected in
2820-437: A set of three narrow coronoid bones lie above the prearticular bone. As the name implies, the majority of the teeth are attached to the dentary, but there are commonly also teeth on the coronoid bones, and sometimes on the prearticular as well. This complex primitive pattern has, however, been simplified to various degrees in the great majority of vertebrates, as bones have either fused or vanished entirely. In teleosts , only
2961-500: A skin secretion from mucous glands. The species Neolamprologus pulcher uses a cooperative breeding system, in which one breeding pair has many helpers that are subordinate to the dominant breeders. Parental care falls into one of four categories: substrate or open brooders, secretive cave brooders (also known as guarding speleophils), and at least two types of mouthbrooders , ovophile mouthbrooders and larvophile mouthbrooders. Open- or substrate-brooding cichlids lay their eggs in
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#17327728529303102-427: A taxon; however, the names published in suppressed works are made unavailable via the relevant Opinion dealing with the work in question. In botany, similar concepts exist but with different labels. The botanical equivalent of zoology's "available name" is a validly published name . An invalidly published name is a nomen invalidum or nom. inval. ; a rejected name is a nomen rejiciendum or nom. rej. ;
3243-558: A time as opposed to the simultaneous replacement of an entire row. However, in piranhas and pacus , all the teeth on one side of the jaw are replaced at a time. Tooth shape depends on the shark's diet: those that feed on mollusks and crustaceans have dense and flattened teeth used for crushing, those that feed on fish have needle-like teeth for gripping, and those that feed on larger prey such as mammals have pointed lower teeth for gripping and triangular upper teeth with serrated edges for cutting. The teeth of plankton-feeders such as
3384-491: A time, attaching them to the spawning surface, which may be a pit constructed on the substrate or another surface. The number of eggs laid was correlated to the space available on the substrate. Once the eggs were attached, the male swam over the eggs and fertilized them. The parents would then dig pits in the sand, 10–20 cm wide and 5–10 cm deep, where larvae were transferred after hatching. Larvae began swimming 8 days after fertilization and parenting behaviors and some of
3525-455: A total of c. 520,000 published names (including synonyms) as at end 2019, increasing at some 2,500 published generic names per year. "Official" registers of taxon names at all ranks, including genera, exist for a few groups only such as viruses and prokaryotes, while for others there are compendia with no "official" standing such as Index Fungorum for fungi, Index Nominum Algarum and AlgaeBase for algae, Index Nominum Genericorum and
3666-425: A true maxilla. Their upper jaw is instead formed from a cartilagenous bar that is not homologous with the bone found in other vertebrates. Some fish have permanently protruding upper jawbones called rostrums . Billfish ( marlin , swordfish and sailfish ) use rostrums (bills) to slash and stun prey. Paddlefish , goblin sharks and hammerhead sharks have rostrums packed with electroreceptors which signal
3807-525: A very wide variety of food items. This is assumed to be one reason why they are so diverse. The features that distinguish them from the other families in the Labroidei include: Kullander (1998) recognizes eight subfamilies of cichlids: the Astronotinae , Cichlasomatinae , Cichlinae , Etroplinae , Geophaginae , Heterochromidinae , Pseudocrenilabrinae , and Retroculinae . A ninth subfamily,
3948-498: A wider variety of foods based on availability. Carnivorous cichlids can be further divided into piscivorous and molluscivorous, since the morphology and hunting behavior differ greatly between the two categories. Piscivorous cichlids eat other fish, fry, larvae, and eggs. Some species eat the offspring of mouthbrooders by head-ramming, wherein the hunter shoves its head into the mouth of a female to expel her young and eat them. Molluscivorous cichlids have several hunting strategies amongst
4089-416: Is a fusion of two bones along the palatal fissure that form the upper jaw . This is similar to the mandible (lower jaw), which is also a fusion of two halves at the mandibular symphysis. In bony fish, the maxilla is called the "upper maxilla," with the mandible being the "lower maxilla". The alveolar process of the maxilla holds the upper teeth, and is referred to as the maxillary arch. In most vertebrates,
4230-414: Is a piece of cartilage from which the mandibles (lower jaws) of vertebrates evolved. Originally it was the lower of two cartilages which supported the first gill arch (nearest the front) in early fish. Then it grew longer and stronger, and acquired muscles capable of closing the developing jaw. In early fish and in chondrichthyans (cartilaginous fish such as sharks ), Meckel's cartilage continued to be
4371-502: Is a reproductive behavior, many different physiological changes occur in the cichlid while this process is occurring that interfere with social interaction. Different kinds of species that pit spawn, and many different morphological changes occur because of this behavioral experience. Pit spawning is an evolved behavior across the cichlid group. Phylogenetic evidence from cichlids in Lake Tanganyika could be helpful in uncovering
Cichlid - Misplaced Pages Continue
4512-404: Is a single structure forming a case around the brain, enclosing the lower surface and the sides, but always at least partially open at the top as a large fontanelle . The most anterior part of the cranium includes a forward plate of cartilage, the rostrum , and capsules to enclose the olfactory organs. Behind these are the orbits, and then an additional pair of capsules enclosing the structure of
4653-513: Is a specialized snail -eater, while Pungu maclareni feeds on sponges . A number of cichlids feed on other fish, either entirely or in part. Crenicichla species are stealth predators that lunge from concealment at passing small fish, while Rhamphochromis species are open-water pursuit predators that chase down their prey. Paedophagous cichlids such as the Caprichromis species eat other species' eggs or young, in some cases ramming
4794-466: Is also the case for Etroplus maculatus and E. suratensis from India and Sri Lanka. Within the cichlid family, carnivores, herbivores, omnivores, planktivores, and detritivores are known, meaning the Cichlidae encompass essentially the full range of food consumption possible in the animal kingdom. Various species have morphological adaptations for specific food sources, but most cichlids consume
4935-716: Is based on body movements, such as shaking and pelvic fin flicking. In addition, open- and cave-brooding parents assist in finding food resources for their fry. Multiple neotropical cichlid species perform leaf-turning and fin-digging behaviors. Ovophile mouthbrooders incubate their eggs in their mouths as soon as they are laid, and frequently mouthbrood free-swimming fry for several weeks. Examples include many East African Rift lakes ( Lake Malawi , Lake Tanganyika , and Lake Victoria ) endemics, e.g.: Maylandia , Pseudotropheus , Tropheus , and Astatotilapia burtoni , along with some South American cichlids such as Geophagus steindachneri . Larvophile mouthbrooders lay eggs in
5076-541: Is believed to have been a spit-spawning species. Both Madagascar and Indian cichlids retain this feature. However, of the African cichlids, all extant substrate brooding species originate solely from Lake Tanganyika. The ancestor of the Lake Malawi and Lake Victoria cichlids were mouthbrooders. Similarly, only around 30% of South American cichlids are thought to retain the ancestral substrate-brooding trait. Mouthbrooding
5217-612: Is discouraged by both the International Code of Zoological Nomenclature and the International Code of Nomenclature for algae, fungi, and plants , there are some five thousand such names in use in more than one kingdom. For instance, A list of generic homonyms (with their authorities), including both available (validly published) and selected unavailable names, has been compiled by the Interim Register of Marine and Nonmarine Genera (IRMNG). The type genus forms
5358-531: Is equally at home in freshwater marshes and mangrove swamps, and lives and breeds in saltwater environments such as the mangrove belts around barrier islands . Several species of Tilapia , Sarotherodon , and Oreochromis are euryhaline and can disperse along brackish coastlines between rivers. Only a few cichlids, however, inhabit primarily brackish or salt water, most notably Etroplus maculatus , Etroplus suratensis , and Sarotherodon melanotheron . The perhaps most extreme habitats for cichlids are
5499-417: Is formed from the pterygoids and vomers alone, all of which bear teeth. Much of the skull is formed from cartilage , and its overall structure is reduced. In vertebrates, the lower jaw ( mandible or jawbone) is a bone forming the skull with the cranium. In lobe-finned fishes and the early fossil tetrapods , the bone homologous to the mandible of mammals is merely the largest of several bones in
5640-515: Is often coupled with some physiological change in appearance. Cichlids can have maternal, paternal, or biparental care. Maternal care is most common among mouthbrooders, but cichlids' common ancestor is thought to exhibit paternal-only care. Other individuals outside of the parents may also play a role in raising young; in the biparental daffodil cichlid ( Neolamprologus pulcher ), closely related satellite males, those males that surround other males' territories and attempt to mate with female cichlids in
5781-568: Is rather common and can also be seen in convict cichlids ( Cichlasoma nigrofasciatum ). Other cichlids have an ectothermal mucus that they grow and feed to their young, while still others chew and distribute caught food to offspring. These strategies, however, are less common in pit-spawning cichlids. Cichlids have highly organized breeding activities. All species show some form of parental care for both eggs and larvae , often nurturing free-swimming young until they are weeks or months old. Communal parental care, where multiple monogamous pairs care for
Cichlid - Misplaced Pages Continue
5922-498: Is regulated by frequency-dependent selection . In cichlids generally, the oral and pharyngeal teeth differ with different species in ways that allow them to process different kinds of prey. Primary oral jaws contain teeth which are used to capture and hold food, while pharyngeal jaws have pharyngeal teeth which function as a chewing tool. This allows for different nutritional strategies, and because of this, cichlids are able to colonize different habitats. The structural diversity of
6063-460: Is somewhat arbitrary. Although all species within a genus are supposed to be "similar", there are no objective criteria for grouping species into genera. There is much debate among zoologists about whether enormous, species-rich genera should be maintained, as it is extremely difficult to come up with identification keys or even character sets that distinguish all species. Hence, many taxonomists argue in favor of breaking down large genera. For instance,
6204-474: Is the type species , and the generic name is permanently associated with the type specimen of its type species. Should the specimen turn out to be assignable to another genus, the generic name linked to it becomes a junior synonym and the remaining taxa in the former genus need to be reassessed. In zoological usage, taxonomic names, including those of genera, are classified as "available" or "unavailable". Available names are those published in accordance with
6345-595: Is thought to have evolved individually up to 14 times, and a return to substrate brooding as many as three separate times between both African and Neotropical species. Cichlids have a great variety of behaviors associated with substrate brooding, including courtship and parental care alongside the brooding and nest-building behaviors needed for pit spawning. Cichlids' behavior typically revolves around establishing and defending territories when not courting, brooding, or raising young. Encounters between males and males or females and females are agonistic, while an encounter between
6486-592: The Cichla species, are valued game fish. The family also includes many popular freshwater aquarium fish kept by hobbyists, including the angelfish , oscars , and discus . Cichlids have the largest number of endangered species among vertebrate families, most in the haplochromine group. Cichlids are particularly well known for having evolved rapidly into many closely related but morphologically diverse species within large lakes, particularly Lakes Tanganyika , Victoria , Malawi , and Edward . Their diversity in
6627-583: The Early Eocene epoch, about 48.6 million years ago; however, molecular clock estimates have placed the family's origin as far back as 67 million years ago, during the late Cretaceous period. The closest living relative of cichlids is probably the convict blenny , and both families are classified in the 5th edition of Fishes of the World as the two families in the Cichliformes, part of
6768-484: The Early Permian about 290 million years ago. The original selective advantage offered by the jaw may not be related to feeding, but rather to increased respiration efficiency. The jaws were used in the buccal pump still observable in modern fish and amphibians , that uses "breathing with the cheeks" to pump water across the gills of fish or air into the lungs in the case of amphibians. Over evolutionary time
6909-621: The International Code of Zoological Nomenclature ; the earliest such name for any taxon (for example, a genus) should then be selected as the " valid " (i.e., current or accepted) name for the taxon in question. Consequently, there will be more available names than valid names at any point in time; which names are currently in use depending on the judgement of taxonomists in either combining taxa described under multiple names, or splitting taxa which may bring available names previously treated as synonyms back into use. "Unavailable" names in zoology comprise names that either were not published according to
7050-824: The International Plant Names Index for plants in general, and ferns through angiosperms, respectively, and Nomenclator Zoologicus and the Index to Organism Names for zoological names. Totals for both "all names" and estimates for "accepted names" as held in the Interim Register of Marine and Nonmarine Genera (IRMNG) are broken down further in the publication by Rees et al., 2020 cited above. The accepted names estimates are as follows, broken down by kingdom: The cited ranges of uncertainty arise because IRMNG lists "uncertain" names (not researched therein) in addition to known "accepted" names;
7191-470: The Ptychochrominae , was later recognized by Sparks and Smith. Cichlid taxonomy is still debated, and classification of genera cannot yet be definitively given. A comprehensive system of assigning species to monophyletic genera is still lacking, and there is not complete agreement on what genera should be recognized in this family. As an example of the classification problems, Kullander placed
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#17327728529307332-971: The Rio Grande in South Texas . Madagascar has its own distinctive species ( Katria , Oxylapia , Paratilapia , Paretroplus , Ptychochromis , and Ptychochromoides ), only distantly related to those on the African mainland. Native cichlids are largely absent in Asia, except for 9 species in Israel , Lebanon , and Syria ( Astatotilapia flaviijosephi , Oreochromis aureus , O. niloticus , Sarotherodon galilaeus , Coptodon zillii , and Tristramella spp.), two in Iran ( Iranocichla ), and three in India and Sri Lanka ( Etroplus and Pseudetroplus ). If disregarding Trinidad and Tobago (where
7473-479: The basking shark and whale sharks are very small. Male salmon often remodel their jaws during spawning runs so they have a pronounced curvature. These hooked jaws are called kypes . The purpose of the kype is not altogether clear, though they can be used to establish dominance by clamping them around the base of the tail ( caudal peduncle ) of an opponent. Fish jaws, like vertebrates in general, normally show bilateral symmetry . An exception occurs with
7614-533: The gums rather than directly affixed to the jaw as in some fish. Shark teeth form within the jaw move outward in rows until they are eventually dislodged in a manner similar to a conveyor belt . Their scales, called dermal denticles , and teeth are homologous organs . Some sharks lose 30,000 or more teeth in their lifetime. The rate of tooth replacement varies from once every 8 to 10 days to several months, although few studies have been able to quantify this. In most species of bony fish , teeth are replaced one at
7755-452: The inner ear . Finally, the skull tapers towards the rear, where the foramen magnum lies immediately above a single condyle , articulating with the first vertebra . There are, in addition, at various points throughout the cranium, smaller foramina for the cranial nerves. The jaws consist of separate hoops of cartilage, almost always distinct from the cranium proper. In ray-finned fishes , there has also been considerable modification from
7896-408: The jaw suspension . There are several archetypal jaw suspensions: amphistyly, orbitostyly, hyostyly, and euhyostyly. In amphistyly, the palatoquadrate has a postorbital articulation with the chondrocranium from which ligaments primarily suspend it anteriorly. The hyoid articulates with the mandibular arch posteriorly, but it appears to provide little support to the upper and lower jaws. In orbitostyly,
8037-457: The new world , can be classified under the subfamily Cichlinae, while Etroplinae can classify all cichlid species native to the old world . Cichlids are one of the largest vertebrate families in the world. They are most diverse in Africa and South America. Africa alone is host to at least an estimated 1,600 species. Central America and Mexico have about 120 species, as far north as
8178-419: The nomenclature codes , which allow each species a single unique name that, for animals (including protists ), plants (also including algae and fungi ) and prokaryotes ( bacteria and archaea ), is Latin and binomial in form; this contrasts with common or vernacular names , which are non-standardized, can be non-unique, and typically also vary by country and language of usage. Except for viruses ,
8319-413: The parasitic scale-eating cichlid Perissodus microlepis . The jaws of this fish occur in two distinct morphological forms. One morph has its jaw twisted to the left, allowing it to eat scales more readily on its victim's right flank. The other morph has its jaw twisted to the right, which makes it easier to eat scales on its victim's left flank. The relative abundance of the two morphs in populations
8460-442: The pelican eel , has jaws larger than its body. The jaws are lined with small teeth and are loosely hinged. They open wide enough to swallow a fish larger than the eel itself. Distichodontidae are a family of fresh water fishes which can be divided into genera with protractile upper jaws which are carnivores , and genera with nonprotractile upper jaws which are herbivores or predators of very small organisms. The appearance of
8601-503: The pharynx , are used to further process the food and move it from the mouth to the stomach. Cartilaginous fishes , such as sharks and rays , have one set of oral jaws made mainly of cartilage . They do not have pharyngeal jaws. Generally jaws are articulated and oppose vertically, comprising an upper jaw and a lower jaw and can bear numerous ordered teeth . Cartilaginous fishes grow multiple sets (polyphyodont) and replace teeth as they wear by moving new teeth laterally from
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#17327728529308742-404: The platypus belongs to the genus Ornithorhynchus although George Shaw named it Platypus in 1799 (these two names are thus synonyms ) . However, the name Platypus had already been given to a group of ambrosia beetles by Johann Friedrich Wilhelm Herbst in 1793. A name that means two different things is a homonym . Since beetles and platypuses are both members of the kingdom Animalia,
8883-462: The premaxilla , with the maxilla itself located further back, and an additional bone, the symplectic, linking the jaw to the rest of the cranium. Although the skulls of fossil lobe-finned fish resemble those of the early tetrapods, the same cannot be said of those of the living lungfishes . The skull roof is not fully formed, and consists of multiple, somewhat irregularly shaped bones with no direct relationship to those of tetrapods. The upper jaw
9024-649: The African Great Lakes is important for the study of speciation in evolution. Many cichlids introduced into waters outside of their natural range have become nuisances. All cichlids practice some form of parental care for their eggs and fry, usually in the form of guarding the eggs and fry or mouthbrooding . Cichlids span a wide range of body sizes, from species as small as 2.5 cm (1 in) in length (e.g., female Neolamprologus multifasciatus ) to much larger species approaching 1 m (3 ft) in length ( Boulengerochromis and Cichla ). As
9165-530: The African cichlids, can be further split either into Eastern and Western varieties, or into groups depending on which lake the species is from: Lake Malawi , Lake Victoria , or Lake Tanganyika . Of these subgroups, the Madagascar and Indian cichlids are the most basal and least diverse. Of the African cichlids, the West African or Lake Tanganyika cichlids are the most basal. Cichlids' common ancestor
9306-540: The African genus Heterochromis phylogenetically within Neotropical cichlids, although later papers concluded otherwise. Other problems center upon the identity of the putative common ancestor for the Lake Victoria superflock (many closely related species sharing a single habitat), and the ancestral lineages of Lake Tanganyikan cichlids. Phylogeny derived from morphological characters shows differences at
9447-560: The North American sunfishes in morphology, behavior, and ecology. Cichlids share a single key trait - the fusion of the lower pharyngeal bones into a single tooth-bearing structure. A complex set of muscles allows the upper and lower pharyngeal bones to be used as a second set of jaws for processing food, allowing a division of labor between the "true jaws" ( mandibles ) and the " pharyngeal jaws ". Cichlids are efficient and often highly specialized feeders that capture and process
9588-494: The anal fin (specifically the genital papilla) of the male, which is when he discharges sperm into her mouth and fertilizes the eggs. The genuine color of egg spots is a yellow, red, or orange inner circle with a colorless ring surrounding the shape. Through phylogenetic analysis, using the mitochondrial ND2 gene, the true egg spots are thought to have evolved in the common ancestor of the Astatoreochromis lineage and
9729-468: The area, help rear the primary males' offspring and their own. A common form of brood care involves food provisioning. For example, females of lyretail cichlids ( Neolamprologus modabu ) dig at sandy substrate more to push nutritional detritus and zooplankton into the surrounding water. Adult of N. modabu perform this strategy to collect food for themselves, but dig more when offspring are present, likely to feed their fry. This substrate-disruption strategy
9870-442: The base for higher taxonomic ranks, such as the family name Canidae ("Canids") based on Canis . However, this does not typically ascend more than one or two levels: the order to which dogs and wolves belong is Carnivora ("Carnivores"). The numbers of either accepted, or all published genus names is not known precisely; Rees et al., 2020 estimate that approximately 310,000 accepted names (valid taxa) may exist, out of
10011-492: The buccal cavity in fishes. The most thorough overview of the different types of linkages in animals has been provided by M. Muller, who also designed a new classification system, which is especially well suited for biological systems. The skull of fishes is formed from a series of loosely connected bones. Lampreys and sharks only possess a cartilaginous endocranium, with both the upper and lower jaws being separate elements. Bony fishes have additional dermal bone , forming
10152-415: The cichlid tribe Haplochromini, exhibit a unique pattern of oval-shaped color dots on their anal fins. These phenomena, known as egg spots, aid in the mouthbrooding mechanisms of cichlids. The egg spots consist of carotenoid-based pigment cells, which indicate a high cost to the organism, when considering that fish are not able to synthesize their own carotenoids. The mimicry of egg spots is used by males for
10293-708: The cranium. Instead, the hyomandibular cartilages provide the only means of jaw support, while the ceratohyal and basihyal elements articulate with the lower jaw, but are disconnected from the rest of the hyoid. Jaws provide a platform in most bony fish for simple pointed teeth , however, there are many exceptions. Some fish like carp and zebrafish have pharyngeal teeth only. Sea horses , pipefish , and adult sturgeon have no teeth of any type. In fish , Hox gene expression regulates mechanisms for tooth initiation. While both sharks and bony fish continuously produce new teeth throughout their lives, they do so via different mechanism. Shark teeth are embedded in
10434-425: The deep remodelling of the vertebrate skull that must have taken place as early jaws evolved. The customary view is that jaws are homologous to the gill arches . In jawless fishes a series of gills opened behind the mouth, and these gills became supported by cartilaginous elements. The first set of these elements surrounded the mouth to form the jaw. The upper portion of the second embryonic arch supporting
10575-419: The deep sea. Relative to their size they have one of the widest gapes of any fish. The lower jaw has no ethmoid membrane (floor) and is attached only by the hinge and a modified tongue bone. There are several large, fang-like teeth in the front of the jaws, followed by many small barbed teeth. There are several groups of pharyngeal teeth that serve to direct food down the esophagus . Another deep sea fish,
10716-475: The dentary, articular, and angular bones remain. Cartilaginous fish , such as sharks , do not have any of the bones found in the lower jaw of other vertebrates. Instead, their lower jaw is composed of a cartilaginous structure homologous with the Meckel's cartilage of other groups. This also remains a significant element of the jaw in some primitive bony fish, such as sturgeons . The upper jaw, or maxilla
10857-891: The details, the general basis of the behavior is the same. Mouthbrooding also affects how they choose their mates and breeding grounds. In a 1995 study, Nelson found that in pit-spawning females choose males for mating based on the size of the pit that they dig, as well as some of the physical characteristics seen in the males. Pit spawning also differs from mouth brooding in the size and postnatal care exhibited. Eggs that have been hatched from pit-spawning cichlids are usually smaller than those of mouthbrooders. Pit-spawners' eggs are usually around 2 mm, while mouthbrooders are typically around 7 mm. While different behaviors take place postnatally between mouthbrooders and pit spawners, some similarities exist. Females in both mouthbrooders and pit-spawning cichlids take care of their young after they are hatched. In some cases, both parents exhibit care, but
10998-426: The developing pharynx of amphioxus and hemichordates . However, the vertebrate pharynx is unique in that it gives rise to endoskeletal support through the contribution of neural crest cells. Cartilaginous fishes ( sharks , rays and skates ) have cartilaginous jaws. The jaw's surface (in comparison to the vertebrae and gill arches) needs extra strength due to its heavy exposure to physical stress. It has
11139-481: The early vertebrate jaw has been described as "a crucial innovation" and "perhaps the most profound and radical evolutionary step in the vertebrate history". Fish without jaws had more difficulty surviving than fish with jaws, and most jawless fish became extinct during the Triassic period. However studies of the cyclostomes , the jawless hagfishes and lampreys that did survive, have yielded little insight into
11280-450: The end of that period, about 360 million years ago. Their largest species, Dunkleosteus terrelli , measured up to 10 m (33 ft) and weighed 3.6 t (4.0 short tons ). It possessed a four bar linkage mechanism for jaw opening that incorporated connections between the skull, the thoracic shield, the lower jaw and the jaw muscles joined together by movable joints. This mechanism allowed Dunkleosteus terrelli to achieve
11421-520: The entire clade and within different communities across separate habitats. Within their phylogeny, many parallel instances are seen of lineages evolving to the same trait and multiple cases of reversion to an ancestral trait. The family Cichlidae arose between 80 and 100 million years ago within the order Perciformes (perch-like fishes). Cichlidae can be split into a few groups based on their geographic location: Madagascar, Indian, African, and Neotropical (or South American). The most famous and diverse group,
11562-462: The evolution of their reproductive behaviors. Several important behaviors are associated with pit spawning, including parental care, food provisioning, and brood guarding. One of the differences studied in African cichlids is reproductive behavior. Some species pit spawn and some are known as mouth brooders. Mouthbrooding is a reproductive technique where the fish scoop up eggs and fry for protection. While this behavior differs from species to species in
11703-768: The female always cares for the eggs and newly hatched fry. Many species of cichlids use pit spawning, but one of the less commonly studied species that exhibits this behavior is the Neotropical Cichlasoma dimerus . This fish is a substrate breeder that displays biparental care after the fry have hatched from their eggs. One study examined reproductive and social behaviors of this species to see how they accomplished their pit spawning, including different physiological factors such as hormone levels, color changes, and plasma cortisol levels. The entire spawning process could take about 90 minutes and 400~800 eggs could be laid. The female deposits about 10 eggs at
11844-438: The fertilization process. Mouthbrooding females lay eggs and immediately snatch them up with their mouths. Over millions of years, male cichlids have evolved egg spots to initiate the fertilization process more efficiently. When the females are snatching up the eggs into their mouth, the males gyrate their anal fins, which illuminates the egg spots on his tail. Afterwards, the female, believing these are her eggs, places her mouth to
11985-973: The few native cichlids are members of genera that are widespread in the South American mainland), the three species from the genus Nandopsis are the only cichlids from the Antilles in the Caribbean , specifically Cuba and Hispaniola . Europe, Australia, Antarctica, and North America north of the Rio Grande drainage have no native cichlids, although in Florida , Hawaii , Japan, northern Australia, and elsewhere, feral populations of cichlids have become established as exotics . Although most cichlids are found at relatively shallow depths, several exceptions do exist. The deepest known occurrences are Trematocara at more than 300 m (1,000 ft) below
12126-408: The foremost part of the upper jaw, to which the incisors are attached in mammals consists of a separate pair of bones, the premaxillae . In bony fish , both maxilla and premaxilla are relatively plate-like bones, forming only the sides of the upper jaw, and part of the face, with the premaxilla also forming the lower boundary of the nostrils . Cartilaginous fish , such as sharks and rays also lack
12267-446: The form "author, year" in zoology, and "standard abbreviated author name" in botany. Thus in the examples above, the genus Canis would be cited in full as " Canis Linnaeus, 1758" (zoological usage), while Hibiscus , also first established by Linnaeus but in 1753, is simply " Hibiscus L." (botanical usage). Each genus should have a designated type , although in practice there is a backlog of older names without one. In zoology, this
12408-399: The full range of parenting behaviours. Secretive cave-spawning cichlids lay their eggs in caves, crevices, holes, or discarded mollusc shells , frequently attaching the eggs to the roof of the chamber. Examples include Pelvicachromis spp., Archocentrus spp., and Apistogramma spp. Free-swimming fry and parents communicate in captivity and in the wild. Frequently, this communication
12549-737: The generic name (or its abbreviated form) still forms the leading portion of the scientific name, for example, Canis lupus lupus for the Eurasian wolf subspecies, or as a botanical example, Hibiscus arnottianus ssp. immaculatus . Also, as visible in the above examples, the Latinised portions of the scientific names of genera and their included species (and infraspecies, where applicable) are, by convention, written in italics . The scientific names of virus species are descriptive, not binomial in form, and may or may not incorporate an indication of their containing genus; for example,
12690-451: The genus level with phylogeny based on genetic loci . A consensus remains that the Cichlidae as a family are monophyletic. In cichlid taxonomy, dentition was formerly used as a classifying characteristic, but this was complicated because in many cichlids, tooth shapes change with age, due to wear, and cannot be relied upon. Genome sequencing and other technologies transformed cichlid taxonomy. Alternatively, all cichlid species native to
12831-420: The gill became the hyomandibular bone of jawed fishes , which supports the skull and therefore links the jaw to the cranium. The hyomandibula is a set of bones found in the hyoid region in most fishes. It usually plays a role in suspending the jaws or the operculum in the case of teleosts . It is now accepted that the precursors of the jawed vertebrates are the long extinct bony (armoured) jawless fish,
12972-585: The heads of mouthbrooding species to force them to disgorge their young. Among the more unusual feeding strategies are those of Corematodus , Docimodus evelynae , Plecodus , Perissodus , and Genyochromis spp., which feed on scales and fins of other fishes, a behavior known as lepidophagy , along with the death-mimicking behaviour of Nimbochromis and Parachromis species, which lay motionless, luring small fish to their side prior to ambush. This variety of feeding styles has helped cichlids to inhabit similarly varied habitats. Its pharyngeal teeth (in
13113-549: The jaw itself (see hyomandibula ) and the hyoid arch , which braces the jaw against the braincase and increases mechanical efficiency. While there is no fossil evidence directly to support this theory, it makes sense in light of the numbers of pharyngeal arches that are visible in extant jawed (the Gnathostomes ), which have seven arches, and primitive jawless vertebrates (the Agnatha ), which have nine. Meckel's cartilage
13254-453: The jaw was probably not related to feeding, but to increased respiration efficiency—the jaws were used in the buccal pump to pump water across the gills. The familiar use of jaws for feeding would then have developed as a secondary function before becoming the primary function in many vertebrates. All vertebrate jaws, including the human jaw, evolved from early fish jaws. The appearance of the early vertebrate jaw has been described as "perhaps
13395-400: The jaw) are then pulled back to close the mouth, and the fish is able to grasp the prey . By contrast, mere closure of the jaws would risk pushing food out of the mouth. In more advanced teleosts, the premaxilla is enlarged and has teeth, while the maxilla is toothless. The maxilla functions to push both the premaxilla and the lower jaw forward. To open the mouth, an adductor muscle pulls back
13536-633: The largest component, with 23,236 ± 5,379 accepted genus names, of which 20,845 ± 4,494 are angiosperms (superclass Angiospermae). By comparison, the 2018 annual edition of the Catalogue of Life (estimated >90% complete, for extant species in the main) contains currently 175,363 "accepted" genus names for 1,744,204 living and 59,284 extinct species, also including genus names only (no species) for some groups. The number of species in genera varies considerably among taxonomic groups. For instance, among (non-avian) reptiles , which have about 1180 genera,
13677-407: The linkage mechanisms of jaw protrusion . For suction feeding a system of linked four-bar linkages is responsible for the coordinated opening of the mouth and the three-dimensional expansion of the buccal cavity . The four-bar linkage is also responsible for protrusion of the premaxilla , leading to three main four-bar linkage systems to generally describe the lateral and anterior expansion of
13818-530: The lizard genus Anolis has been suggested to be broken down into 8 or so different genera which would bring its ~400 species to smaller, more manageable subsets. Oral jaw Most bony fishes have two sets of jaws made mainly of bone . The primary oral jaws open and close the mouth, and a second set of pharyngeal jaws are positioned at the back of the throat. The oral jaws are used to capture and manipulate prey by biting and crushing. The pharyngeal jaws, so-called because they are positioned within
13959-409: The lower jaw. It is referred to as the dentary bone , and forms the body of the outer surface of the jaw. It is bordered below by a number of splenial bones, while the angle of the jaw is formed by a lower angular bone and a suprangular bone just above it. The inner surface of the jaw is lined by a prearticular bone, while the articular bone forms the articulation with the skull proper. Finally
14100-420: The lower pharyngeal jaw could be one of the reasons for the occurrence of so many cichlid species. Convergent evolution took place over the course of the cichlid radiation, synchronous with different trophic niches. The pharyngeal jaw apparatus consists of two upper and one single lower plate, all of which have dentations that differ in size and type. The structure of the lower pharynx is often associated with
14241-474: The main component of the lower jaw. But in the adult forms of osteichthyans (bony fish) and their descendants (amphibians, reptiles, birds and mammals) the cartilage was covered in bone – although in their embryos the jaw initially develops as the Meckel's cartilage. In tetrapods the cartilage partially ossifies (changes to bone) at the rear end of the jaw and becomes the articular bone, which forms part of
14382-524: The medial jaw surface in a conveyor-belt fashion. Teeth are replaced multiple times also in most bony fishes, but unlike cartilaginous fishes, the new tooth erupts only after the old one has fallen out. Jaws probably originated in the pharyngeal arches supporting the gills of jawless fish . The earliest jaws appeared in now extinct placoderms and spiny sharks during the Silurian , about 430 million years ago. The original selective advantage offered by
14523-599: The modern Haplochrominis species. This ancestor was most likely riverine in origin, based on the most parsimonious representation of habitat type in the cichlid family. The presence of egg spots in a turbid riverine environment would seem particularly beneficial and necessary for intraspecies communication. Two pigmentation genes are found to be associated with egg-spot patterning and color arrangement. These are fhl2-a and fhl2-b , which are paralogs. These genes aid in pattern formation and cell-fate determination in early embryonic development. The highest expression of these genes
14664-443: The more familiar use of jaws (to humans), in feeding, was selected for and became a very important function in vertebrates. Many teleost fish have substantially modified jaws for suction feeding and jaw protrusion , resulting in highly complex jaws with dozens of bones involved. Jaws are thought to derive from the pharyngeal arches that support the gills in fish. The two most anterior of these arches are thought to have become
14805-403: The most (>300) have only 1 species, ~360 have between 2 and 4 species, 260 have 5–10 species, ~200 have 11–50 species, and only 27 genera have more than 50 species. However, some insect genera such as the bee genera Lasioglossum and Andrena have over 1000 species each. The largest flowering plant genus, Astragalus , contains over 3,000 species. Which species are assigned to a genus
14946-404: The most profound and radical evolutionary step in the vertebrate history". Fish without jaws had more difficulty surviving than fish with jaws, and most jawless fish became extinct. Jaws use linkage mechanisms . These linkages can be especially common and complex in the head of bony fishes , such as wrasses , which have evolved many specialized feeding mechanisms . Especially advanced are
15087-428: The name could not be used for both. Johann Friedrich Blumenbach published the replacement name Ornithorhynchus in 1800. However, a genus in one kingdom is allowed to bear a scientific name that is in use as a generic name (or the name of a taxon in another rank) in a kingdom that is governed by a different nomenclature code. Names with the same form but applying to different taxa are called "homonyms". Although this
15228-716: The open or in a cave and take the hatched larvae into the mouth. Examples include some variants of Geophagus altifrons , and some Aequidens , Gymnogeophagus , and Satanoperca , as well as Oreochromis mossambicus and Oreochromis niloticus . Mouthbrooders, whether of eggs or larvae, are predominantly females. Exceptions that also involve the males include eretmodine cichlids (genera Spathodus , Eretmodus , and Tanganicodus ), some Sarotherodon species (such as Sarotherodon melanotheron ), Chromidotilapia guentheri , and some Aequidens species. This method appears to have evolved independently in several groups of African cichlids. Genus The composition of
15369-436: The open, on rocks, leaves, or logs. Examples of open-brooding cichlids include Pterophyllum and Symphysodon species and Anomalochromis thomasi . Male and female parents usually engage in differing brooding roles. Most commonly, the male patrols the pair's territory and repels intruders, while the female fans water over the eggs, removing the infertile ones, and leading the fry while foraging. Both sexes are able to perform
15510-400: The oral jaw, the pharyngeal jaw has no jaw joint, but is supported instead by a sling of muscles. A notable example occurs with the moray eel . The pharyngeal jaws of most fishes are not mobile. The pharyngeal jaws of the moray are highly mobile, perhaps as an adaptation to the constricted nature of the burrows they inhabit which inhibits their ability to swallow as other fishes do by creating
15651-410: The orbital process hinges with the orbital wall and the hyoid provides the majority of suspensory support. In contrast, hyostyly involves an ethmoid articulation between the upper jaw and the cranium, while the hyoid most likely provides vastly more jaw support compared to the anterior ligaments. Finally, in euhyostyly, also known as true hyostyly, the mandibular cartilages lack a ligamentous connection to
15792-810: The physical aggression of males becomes a contest for resources (mates, territory, food). Female cichlids prefer to mate with a successfully alpha male with vivid coloration, whose territory has food readily available. Cichlids mate either monogamously or polygamously . The mating system of a given cichlid species is not consistently associated with its brooding system. For example, although most monogamous cichlids are not mouthbrooders, Chromidotilapia , Gymnogeophagus , Spathodus , and Tanganicodus all include – or consist entirely of – monogamous mouthbrooders. In contrast, numerous open- or cave-spawning cichlids are polygamous; examples include many Apistogramma , Lamprologus , Nannacara , and Pelvicachromis species. Most adult male cichlids, specifically in
15933-407: The physiological factors measured changed. In the same study, color changes were present before and after the pit spawning occurred. For example, after the larvae were transferred and the pits were beginning to be protected, their fins turned a dark grey color. In another study, of the rainbow cichlid, Herotilapia multispinosa , color changes occurred throughout the spawning process. Before spawning,
16074-645: The precise sister relationships predicted by vicariance : Africa-South America and India-Madagascar. The dispersal hypothesis, in contrast, requires cichlids to have negotiated thousands of kilometers of open ocean between India and Madagascar without colonizing any other island, or for that matter, crossing the Mozambique Channel to Africa. Although the vast majority of Malagasy cichlids are entirely restricted to fresh water, Ptychochromis grandidieri and Paretroplus polyactis are commonly found in coastal brackish water and are apparently salt tolerant, as
16215-425: The premaxilla as the mouth is opened and closed. These protrusible jaws are evolutionary novelties in teleosts that evolved independently at least five times. The premaxilla is unattached to the neurocranium (braincase); it plays a role in protruding the mouth and creating a circular opening. This lowers the pressure inside the mouth, sucking the prey inside. The lower jaw and maxilla (main upper fixed bone of
16356-403: The presence of prey by detecting weak electrical fields. Sawsharks and the critically endangered sawfish have rostrums (saws) which are both electro-sensitive and used for slashing. The rostrums extend ventrally in front of the fish. In the case of hammerheads the rostrum (hammer) extends both ventrally and laterally (sideways). Teleosts have a movable premaxilla (a bone at the tip of
16497-418: The pressure of reproduction, and establish their territory and social status by physically driving out challenging males (novel intruders) through lateral displays (parallel orientation, uncovering gills), biting, or mouth fights (head-on collisions of open mouths, measuring jaw sizes, and biting each other's jaws). The cichlid social dichotomy is composed of a single dominant with multiple subordinates, where
16638-402: The primitive pattern. The roof of the skull is generally well formed, and although the exact relationship of its bones to those of tetrapods is unclear, they are usually given similar names for convenience. Other elements of the skull, however, may be reduced; there is little cheek region behind the enlarged orbits, and little, if any bone in between them. The upper jaw is often formed largely from
16779-541: The provisions of the ICZN Code, e.g., incorrect original or subsequent spellings, names published only in a thesis, and generic names published after 1930 with no type species indicated. According to "Glossary" section of the zoological Code, suppressed names (per published "Opinions" of the International Commission of Zoological Nomenclature) remain available but cannot be used as the valid name for
16920-402: The rainbow cichlid was an olive color with grey bands. Once spawning behaviors started, the body and fins of the fish became a more golden color. When the eggs were finished being laid, the pelvic fin all the way back to the caudal fin turned to a darker color and blackened in both the males and the females. Females prefer a bigger pit size when choosing where to lay eggs. Differences are seen in
17061-532: The rigid neurocranium , and the superior and inferior articulations of the maxilla are joined to the anterior tips of these two bones, respectively, creating a loop of 4 rigid bones connected by moving joints. This " four-bar linkage " has the property of allowing numerous arrangements to achieve a given mechanical result (fast jaw protrusion or a forceful bite), thus decoupling morphology from function. The actual morphology of wrasses reflects this, with many lineages displaying different jaw morphology that results in
17202-526: The same functional output in a similar or identical ecological niche. The most extreme jaw protrusion found in fishes occurs in the slingjaw wrasse , Epibulus insidiator . This fish can extend its jaws up to 65% the length of its head. This species utilizes its quick and extreme jaw protrusion to capture smaller fishes and crustaceans. The genus this species belongs to possess one unique ligament (vomero-interopercular) and two enlarged ligaments (interoperculo-mandibular and premaxilla-maxilla), which along with
17343-470: The same kind as other (analogous) genera. The term "genus" comes from Latin genus , a noun form cognate with gignere ('to bear; to give birth to'). The Swedish taxonomist Carl Linnaeus popularized its use in his 1753 Species Plantarum , but the French botanist Joseph Pitton de Tournefort (1656–1708) is considered "the founder of the modern concept of genera". The scientific name (or
17484-408: The scientific epithet) of a genus is also called the generic name ; in modern style guides and science, it is always capitalised. It plays a fundamental role in binomial nomenclature , the system of naming organisms , where it is combined with the scientific name of a species : see Botanical name and Specific name (zoology) . The rules for the scientific names of organisms are laid down in
17625-406: The sizes of pits that created, as well as a change in the morphology of the pits. Evolutionary differences between species of fish may cause them to either create pits or castles when spawning. The differences were changes in the way that each species fed, their macrohabitats, and the abilities of their sensory systems. Cichlids are renowned for their recent, rapid evolutionary radiation, both across
17766-460: The so-called ostracoderms . The earliest known fish with jaws are the now extinct placoderms and spiny sharks . Placoderms were a class of fish, heavily armoured at the front of their body, which first appeared in the fossil records during the Silurian about 430 million years ago. Initially they were very successful, diversifying remarkably during the Devonian . They became extinct by
17907-651: The species of food of the species. In order to crack shellfish considerable force must be generated, which is why cichlids that feed on molluscs (e.g. the cichlid bass, Crenicichla minuano ), have molariform teeth and a strengthened jawbone bone. To grab and bite prey not armoured with shells, predators need conical, bent back teeth. Herbivorous cichlids also have structural differences in their teeth. Cichlids that specialise in algae (e.g. Pseudotropheus ) tend to have small conical teeth. Species that feed on pods or seeds require large conical teeth for chewing their food. Stoplight loosejaws are small fish found worldwide in
18048-497: The specific name particular to the wolf. A botanical example would be Hibiscus arnottianus , a particular species of the genus Hibiscus native to Hawaii. The specific name is written in lower-case and may be followed by subspecies names in zoology or a variety of infraspecific names in botany . When the generic name is already known from context, it may be shortened to its initial letter, for example, C. lupus in place of Canis lupus . Where species are further subdivided,
18189-412: The standard format for a species name comprises the generic name, indicating the genus to which the species belongs, followed by the specific epithet, which (within that genus) is unique to the species. For example, the gray wolf 's scientific name is Canis lupus , with Canis ( Latin for 'dog') being the generic name shared by the wolf's close relatives and lupus (Latin for 'wolf') being
18330-466: The subseries Ovalentaria . This family is large, diverse, and widely dispersed. At least 1,650 species have been scientifically described , making it one of the largest vertebrate families. New species are discovered annually, and many species remain undescribed . The actual number of species is therefore unknown, with estimates varying between 2,000 and 3,000. Many cichlids, particularly tilapia , are important food fishes, while others, such as
18471-700: The surface in Lake Tanganyika . Others found in relatively deep waters include species such as Alticorpus macrocleithrum and Pallidochromis tokolosh down to 150 m (500 ft) below the surface in Lake Malawi, and the whitish (non pigmented ) and blind Lamprologus lethops , which is believed to live as deep as 160 m (520 ft) below the surface in the Congo River . Cichlids are less commonly found in brackish and saltwater habitats, though many species tolerate brackish water for extended periods; Mayaheros urophthalmus , for example,
18612-403: The taxon is termed a synonym ; some authors also include unavailable names in lists of synonyms as well as available names, such as misspellings, names previously published without fulfilling all of the requirements of the relevant nomenclatural code, and rejected or suppressed names. A particular genus name may have zero to many synonyms, the latter case generally if the genus has been known for
18753-405: The throat) afford cichlids so many "niche" feeding strategies, because the jaws pick and hold food, while the pharyngeal teeth crush the prey. Aggressive behavior in cichlids is ritualized and consists of multiple displays used to seek confrontation while being involved in evaluation of competitors, coinciding with temporal proximity to mating. Displays of ritualized aggression in cichlids include
18894-405: The top of the maxilla, pushing the lower jaw forward. In addition, the maxilla rotates slightly, which pushes forward a bony process that interlocks with the premaxilla. Teleosts achieve this jaw protrusion using one of four different mechanisms involving the ligamentous linkages within the skull. Some teleosts use more than one of these mechanisms (e.g. Petrotilapia ). Wrasses have become
19035-412: The upper jaw) and corresponding modifications in the jaw musculature which make it possible for them to protrude their jaws outwards from the mouth . This is of great advantage, enabling them to grab prey and draw it into the mouth . In more derived teleosts, the enlarged premaxilla is the main tooth-bearing bone, and the maxilla, which is attached to the lower jaw, acts as a lever, pushing and pulling
19176-576: The values quoted are the mean of "accepted" names alone (all "uncertain" names treated as unaccepted) and "accepted + uncertain" names (all "uncertain" names treated as accepted), with the associated range of uncertainty indicating these two extremes. Within Animalia, the largest phylum is Arthropoda , with 151,697 ± 33,160 accepted genus names, of which 114,387 ± 27,654 are insects (class Insecta). Within Plantae, Tracheophyta (vascular plants) make up
19317-477: The varieties within the group. Lake Malawi cichlids consume substrate and filter it out through their gill rakers to eat the mollusks that were in the substrate. Gill rakers are finger-like structures that line the gills of some fish to catch any food that might escape through their gills. Many cichlids are primarily herbivores , feeding on algae (e.g. Petrochromis ) and plants (e.g. Etroplus suratensis ). Small animals, particularly invertebrates , are only
19458-429: The virus species " Salmonid herpesvirus 1 ", " Salmonid herpesvirus 2 " and " Salmonid herpesvirus 3 " are all within the genus Salmonivirus ; however, the genus to which the species with the formal names " Everglades virus " and " Ross River virus " are assigned is Alphavirus . As with scientific names at other ranks, in all groups other than viruses, names of genera may be cited with their authorities, typically in
19599-491: The warm hypersaline lakes where the members of the genera Alcolapia and Danakilia are found. Lake Abaeded in Eritrea encompasses the entire distribution of D. dinicolai , and its temperature ranges from 29 to 45 °C (84 to 113 °F). With the exception of the species from Cuba, Hispaniola, and Madagascar, cichlids have not reached any oceanic island and have a predominantly Gondwanan distribution, showing
19740-470: Was perfectly adapted to prey on free-swimming, armoured prey like arthropods, ammonites, and other placoderms. Spiny sharks were another class of fish which appeared also in the fossil records during the Silurian at about the same time as the placoderms. They were smaller than most placoderms, usually under 20 centimetres. Spiny sharks did not diversify as much as placoderms, but survived much longer into
19881-518: Was temporally correlated with egg-spot formation. A short, interspersed, repetitive element was also seen to be associated with egg spots. Specifically, it was evident upstream of the transcriptional start site of fhl2 in only Haplochrominis species with egg spots The cichlid Benitochromis nigrodorsalis from Western Africa ordinarily undergoes biparental reproduction, but is also able to undergo facultative (optional) selfing ( self-fertilization ). Facultative selfing may be an adaptive option when
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