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91-568: Iguana ( / ɪ ˈ ɡ w ɑː n ə / , Spanish: [iˈɣwana] ) is a genus of herbivorous lizards that are native to tropical areas of Mexico , Central America , South America , and the Caribbean . The genus was first described in 1768 by Austrian naturalist Josephus Nicolaus Laurenti in his book Specimen Medicum, Exhibens Synopsin Reptilium Emendatam cum Experimentis circa Venena . Two species are placed in

182-558: A diurnal cycle , becoming dark at day and pale at night. The skin also has photoreceptors , light sensitive cells, most of them concentrated in the tail, which helps them to stay buried. Lampreys may spend up to eight years as ammocoetes, while species such as the Arctic lamprey may only spend one to two years as larvae, prior to undergoing a metamorphosis which generally lasts 3–4 months, but can vary between species. While metamorphosing, they do not eat. The rate of water moving across

273-402: A notochord , dorsal hollow nerve cord , pharyngeal slits , pituitary gland / endostyle , and a post anal tail during the process of their development are considered to be chordates . Lampreys contain these characteristics that define them as chordates. Lamprey anatomy is very different based on what stage of development they are in. The notochord is derived from the mesoderm and is one of

364-498: A dark-colored back, which enables them to blend in with the ground below when seen from above by a predator. Their light-colored undersides allow them to blend in with the bright air and water above them if a predator sees them from below. Lamprey coloration can also vary according to the region and specific environment in which the species is found. Some species can be distinguished by their unique markings – for example, Geotria australis individuals display two bluish stripes running

455-617: A distinctive population, and recognizes I. insularis and I. melanoderma as subspecies of I. iguana . Four subspecies of green iguana are recognized under this treatment: I. i. insularis ( Saint Vincent & the Grenadines and Grenada ), I. i. sanctaluciae ( Saint Lucia ), I. i. melanoderma (parts of the northern Lesser Antilles, and potentially coastal Venezuela , the Virgin Islands , and Puerto Rico ), and I. i. iguana (mainland South America). Two extant species in

546-407: 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

637-435: A higher bite force relative to their size in comparison to carnivorous or omnivorous reptiles. The skull of the iguana has undergone modifications resulting in a strong bite force and efficient processing of vegetation , according to one study. To accomplish this biomechanically , herbivorous lizards have taller and wider skulls, shorter snouts, and larger bodies relative to carnivorous and omnivorous reptiles. Increasing

728-651: 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

819-628: 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,

910-840: A low tolerance for high water temperatures, which may explain why they are not distributed in the tropics. Lamprey distribution may be adversely affected by river habitat loss, overfishing and pollution. In Britain, at the time of the 11th-century Norman Conquest of England, lampreys were found as far upstream in the River Thames as Petersham . The reduction of pollution in the Thames and River Wear has led to recent sightings in London and Chester-le-Street . Distribution of lampreys may also be adversely affected by dams and other construction projects due to disruption of migration routes and obstruction of access to spawning grounds. Conversely,

1001-411: A model system to work out the fundamental principles of motor control in vertebrates starting in the spinal cord and working toward the brain. In a series of studies by Rovainen and his student James Buchanan, the cells that formed the neural circuits within the spinal cord capable of generating the rhythmic motor patterns that underlie swimming were examined. Note that there are still missing details in

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1092-409: 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

1183-441: A single pair of regular eyes as well as two parietal eyes : a pineal and parapineal one (the exception is members of Mordacia ). The eyes of juvenile lampreys are poorly developed eyespot-like structures that are covered in non-transparent skin, while the eyes of adult lampreys are well developed. Accommodation is done by flattening the cornea, which pushes the lens towards the retina. The eye of family Mordaciidae possess just

1274-423: A single type of photoreceptor (rod-like), the family Petromyzontidae possess two photoreceptor types (a cone-like and a rod-like), and the family Geotriidae possesses five types of photoreceptors. The buccal cavity , anterior to the gonads , is responsible for attaching the animal, through suction, to either a stone or its prey. This then allows the tongue to make contact with the stone to rasp algae , or tear at

1365-446: A small number of radially arranged teeth, they lacked the specialised, heavily toothed discs with plate-like laminae present in modern lampreys, and it is possible that they fed by scraping algae off of animals, rather than feeding by predation/parasitism. They also lacked the modern three stage life cycle including ammocoetes found in modern lampreys, with the juvenile stages of these species closely resembling adults. Myxineidus from

1456-602: A subspecies of I. iguana . The Curaçao population of green iguanas shows major genetic divergence and may also represent an as-of-yet undescribed species or subspecies. Iguanas have historically featured in the culinary traditions of Mexico and Central America. Iguana meat is also consumed in parts of the United States and Puerto Rico. Also, the eggs of iguana are consumed in some parts of Latin America, such as Nicaragua and Colombia. Genus The composition of

1547-449: A sucking mouth. Those that are anadromous are carnivorous, feeding on fishes or marine mammals. Anadromous lampreys spend up to four years in the sea before migrating back to freshwater, where they spawn. Adults create nests (called redds ) by moving rocks, and females release thousands of eggs, sometimes up to 100,000. The male, intertwined with the female, fertilizes the eggs simultaneously. Being semelparous , both adults die after

1638-427: 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. ;

1729-455: 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

1820-415: Is anterior to the intestines. It contains the sinus , one atrium , and one ventricle protected by the pericardial cartilages. The pineal gland , a photosensitive organ regulating melatonin production by capturing light signals through the photoreceptor cell converting them into intercellular signals of the lamprey is located in the midline of its body, for lamprey, the pineal eye is accompanied by

1911-490: Is called tongue prehension . Iguanians are the only lineage within the Squamata that display this trait, meaning that it was gained independently in both iguanians and tuataras. Iguanians are also the only squamates that primarily use their sight to identify and track prey rather than chemoreception or scent, and employ an ambush technique of catching prey instead of active searching. A study by Breuil et al. (2020) found

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2002-457: Is characterized by a toothed, funnel-like sucking mouth. The common name "lamprey" is probably derived from Latin lampetra , which may mean "stone licker" ( lambere "to lick" + petra "stone"), though the etymology is uncertain. Lamprey is sometimes seen for the plural form. There are about 38 known extant species of lampreys and around seven known extinct species. They are classified in three families: two small families in

2093-581: Is derived from the original Taino name for the species, iwana . In addition to the two species in the genus Iguana , several other related genera in the same family have common names of the species including the word "iguana". The species is a popular quarry for pets , and non-native animals have been widely introduced beyond its native area, into Ishigaki Island , the Florida Peninsula , Hawaii , Singapore , Thailand , Taiwan , and including numerous islands with native Iguana populations in

2184-612: 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

2275-536: Is inserted into the female's cloacal vent . A female can store sperm from previous mates for several years to continue to fertilize her eggs in case she finds no male within her territory when she is ready to lay again. Iguanas tend to follow a promiscuous or polygynandrous mating style during the dry season. Mating during the dry season ensures that their offspring will hatch during the wet or rainy season when food will be more plentiful. Females control large territories, where they make several nests. Males compete for

2366-460: 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,

2457-474: 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

2548-621: 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

2639-824: 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;

2730-589: The Jurassic Period , around 163 million years ago, with the modern families likely splitting from each sometime between the Middle Jurassic and the end of the Cretaceous . Modern lampreys spend the majority of their life in the juvenile "ammocoete" stage, where they burrow into the sediment and filter feed . Adult carnivorous lampreys are the most well-known species, and feed by boring into

2821-477: The Lesser Antilles . Iguanas are large lizards that can range from 1.2 to 2.0 m (4 to 6.5 ft) in length, including their tails. They possess a dewlap and a row of elongated scales running from the midline of their necks down to their tails . Iguanas have varying types of scales covering different areas of their body; for example, some large, round tuberculate scales are scattered around

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2912-632: The Southern Hemisphere ( Geotriidae , Mordaciidae ) and one large family in the Northern Hemisphere ; ( Petromyzontidae ). Genetic evidence suggests that lampreys are more closely related to hagfish , the only other living group of jawless fish, than they are to jawed vertebrates , forming the superclass Cyclostomi . The oldest fossils of stem-group lampreys are from the latest Devonian Period , around 360 million years ago, with modern looking forms only appearing during

3003-456: The T cells and B cells present in higher vertebrates immune system. Pouched lamprey ( Geotria australis ) larvae also have a very high tolerance for free iron in their bodies, and have well-developed biochemical systems for detoxification of the large quantities of these metal ions. The adults spawn in nests of sand, gravel and pebbles in clear streams. After hatching from the eggs, young larvae—called ammocoetes —will drift downstream with

3094-419: 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 ,

3185-529: The otic vesicle . The lamprey has been extensively studied because its relatively simple brain is thought in many respects to reflect the brain structure of early vertebrate ancestors. Beginning in the 1970s, Sten Grillner and his colleagues at the Karolinska Institute in Stockholm followed on from extensive work on the lamprey started by Carl Rovainen in the 1960s that used the lamprey as

3276-403: The pharyngeal slits , are openings found between the pharynx or throat. Pharyngeal slits are filter feeding organs that help the movement of water through the mouth and out of these slits when feeding. During the lamprey's larval stage they feed by filter feeding. Once lampreys reach their adult phase they become parasitic on other fish, and these gill slits become very important in aiding in

3367-400: The phylum Chordata , which also includes the invertebrate subphyla Tunicata (sea-squirts) and the fish-like Cephalochordata ( lancelets or Amphioxus). Recent molecular and morphological phylogenetic studies place lampreys and hagfish in the infraphylum Agnatha or Agnathostomata (both meaning without jaws). The other vertebrate infraphylum is Gnathostomata (jawed mouths) and includes

3458-404: 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,

3549-548: The subclade Iguania is in a group with snakes and anguimorphs (lizards). These groups share an oral gland capable of secreting toxins (a derived trait). The phylogeny based on whole mitochondrial genomes , though, as proposed by Rest et al. (2003), places the green iguana as the closest relative of the mole skink ( Plestiodon egregius ). Lepidosaurs are reptiles with overlapping scales, and within this group both iguanians and tuataras ( Sphenodon ) project their tongues to seize prey items instead of using their jaws, which

3640-1072: The 20th century, both names were used indiscriminately, even by the same author in subsequent publications. In the mid-1970s, the ICZN was called upon to fix one name or the other, and after much debate had to resolve the issue by voting. Thus, in 1980, the spelling with a "t" won out, and in 1981, it became official that all higher-level taxa based on Petromyzon have to start with "Petromyzont-". Phylogeny based on Brownstein & Near, 2023. Geotria Gray 1851 (pouched lampreys) Mordacia Gray 1853 (southern topeyed lampreys) Caspiomyzon Berg 1906 Petromyzon Linnaeus 1758 ( Sea lamprey ) Ichthyomyzon Girard 1858 Entosphenus Gill 1863 Tetrapleurodon Creaser & Hubbs 1922 (Mexican lampreys) Western American " Lampetra " Lethenteron Creaser & Hubbs 1922 Eudontomyzon Regan 1911 Lampetra sensu stricto Bonnaterre 1788 (Eastern American and European Lampetra ) Recent studies differ regarding

3731-571: The Carboniferous of France, often considered to be a hagfish , has been found to be a lamprey in some studies. The earliest lamprey with the specialised toothed oral disc typical of modern lampreys is Yanliaomyzon from the Middle Jurassic of China around 163 million years old, which is thought to have had a predatory lifestyle like modern lampreys, and probably had a three stage life cycle including ammocoetes. Mesomyzon from

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3822-472: The Early Cretaceous of China, which displays the three stage life cycle with ammocoetes, was found in one study to be more closely related to the family Petromyzonidae than to other living lampreys, though other studies have found it to be outside the group containing all living lampreys. Synapomorphies are certain characteristics that are shared over evolutionary history. Organisms possessing

3913-516: The Grenadines horned iguana, I. i. insularis ) were originally described as subspecies of I. iguana , although they are genetically very similar and may not be separate subspecies from one another. Recent studies have recovered I. rhinolopha and I. insularis as distinct species based on genetics, but the Reptile Database disagrees with these conclusions, and classifies I. rhinolopha as synonymous with I. iguana , and I. insularis as

4004-732: The Southern Hemisphere. It is thought that most modern lamprey diversity emerged during the Cenozoic, particularly within the last 10–20 million years. The oldest fossil lamprey, Priscomyzon , is known from the latest Devonian of South Africa around 360 million years ago, with other stem-group lampreys, like Pipiscius , Mayomyzon and Hardistiella known from the Carboniferous of North America. These Paleozoic stem-lampreys are small relative to modern lampreys, and while they had well developed oral discs with

4095-612: The World classifies lampreys within the Class Petromyzontida, a taxon called Petromyzonti in Eschmeyer's Catalog of Fishes . The debate about their systematics notwithstanding, lampreys constitute a single order Petromyzontiformes . Sometimes still seen is the alternative spelling "Petromyzoniformes" , based on the argument that the type genus is Petromyzon and not "Petromyzonta" or similar. Throughout most of

4186-473: The ammocoetes' feeding apparatus is the lowest recorded in any suspension feeding animal, and they therefore require water rich in nutrients to fulfill their nutritional needs. While the majority of (invertebrate) suspension feeders thrive in waters containing under 1 mg suspended organic solids per litre (<1 mg/L), ammocoetes demand minimum 4 mg/L, with concentrations in their habitats having been measured up to 40 mg/L. During metamorphosis

4277-408: The animal attach itself to its prey. Made of keratin and other proteins, lamprey teeth have a hollow core to give room for replacement teeth growing under the old ones. Some of the original blood-feeding forms have evolved into species that feed on both blood and flesh, and some who have become specialized to eat flesh and may even invade the internal organs of the host. Tissue feeders can also involve

4368-442: 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

4459-568: The body, which pull rather than push their bodies through the water. Different species of lamprey have many shared physical characteristics. The same anatomical structure can serve different functions in the lamprey depending on whether or not it is carnivorous . The mouth and suction capabilities of the lamprey not only allow it to cling to a fish as a parasite , but provide it with limited climbing ability so that it can travel upstream and up ramps or rocks to breed. This ability has been studied in an attempt to better understand how lampreys battle

4550-596: The classes Chondrichthyes (sharks), Osteichthyes (bony fishes), Amphibia , Reptilia , Aves , and Mammalia . Some researchers have classified lampreys as the sole surviving representatives of the Linnean class Cephalaspidomorphi . Cephalaspidomorpha is sometimes given as a subclass of the Cephalaspidomorphi. Fossil evidence now suggests lampreys and cephalaspids acquired their shared characters by convergent evolution . The 5th edition of Fishes of

4641-537: The construction of artificial channels has exposed new habitats for colonisation, notably in North America where sea lampreys have become a significant introduced pest in the Great Lakes . Active control programs to control lampreys are undergoing modifications due to concerns of drinking water quality in some areas. Adults superficially resemble eels in that they have scaleless , elongated bodies, with

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4732-502: The current and move forward despite only being able to hold onto the rock at a single point. Some scientists are also hoping to design ramps that will optimize the lamprey's climbing ability, as lampreys are valued as food in the Northwest United States and need to travel upstream to reproduce. Many lampreys exhibit countershading , a form of camouflage . Similarly to many other aquatic species, most lampreys have

4823-429: The current till they reach soft and fine sediment in silt beds, where they will burrow in silt, mud and detritus, taking up an existence as filter feeders, collecting detritus, algae, and microorganisms. The eyes of the larvae are underdeveloped, but are capable of discriminating changes in illuminance. Ammocoetes can grow from 3–4 inches (8–10 centimetres) to about 8 inches (20 cm). Many species change color during

4914-410: The defining characteristics of a chordate. The notochord provides signaling and mechanical cues to help the organism when swimming. The dorsal nerve cord is another characteristic of lampreys that defines them as chordates. During development this part of the ectoderm rolls creating a hollow tube. This is often why it is referred to as the dorsal "hollow" nerve cord. The third chordate feature, which are

5005-421: The eggs are fertilized. Research on sea lampreys has revealed that sexually mature males use a specialized heat-producing tissue in the form of a ridge of fat cells near the anterior dorsal fin to stimulate females. After having attracted a female with pheromones, the heat detected by the female through body contact will encourage spawning. Taxonomists place lampreys and hagfish in the subphylum Vertebrata of

5096-771: The females in an area and mark their won territory with a pheromone secreted from the femoral pores on the dorsal side of their hind limbs. Male behavior during sexual competition involves head bobbing, extending and retracting their dewlap , nuzzling and biting the necks of females, and on occasion, changing color. Once a female chooses a male, he straddles the female and holds her in place by biting onto her shoulder, which sometimes leaves scars on females. After copulation, eggs are laid within several nests and allowed to incubate. This low level of parental intervention with their offspring makes iguanas an example of r-strategy reproduction. A phylogeny based on nuclear protein-coding genes, reviewed by Vidal and Hedges (2009), suggested that

5187-473: The flesh of other fish (or in rare cases marine mammals) to consume flesh and/or blood ; but only 18 species of lampreys engage in this predatory lifestyle (with Caspiomyzon suggested to feed on carrion rather than live prey ). Of the 18 carnivorous species, nine migrate from saltwater to freshwater to breed (some of them also have freshwater populations), and nine live exclusively in freshwater. All non-carnivorous forms are freshwater species. Adults of

5278-492: The flesh of their prey to yield blood. The last common ancestor of lampreys appears to have been specialized to feed on the blood and body fluids of other fish after metamorphosis. They attach their mouthparts to the target animal's body, then use three horny plates (laminae) on the tip of their piston-like tongue, one transversely and two longitudinally placed, to scrape through surface tissues until they reach body fluids. The teeth on their oral disc are primarily used to help

5369-446: 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

5460-737: 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,

5551-525: The genus Iguana are widely recognized. Three Caribbean subspecies of the green iguana are also recognized: The Central American iguana ( I. rhinolopha or I. i. rhinolopha ), sometimes considered a distinct species, is largely considered synonymous with I. iguana , as the presence of horns does not necessarily indicate a new species or subspecies. The two described subspecies of I. insularis (the Saint Lucia horned iguana, I. i. sanctaluciae , and

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5642-544: The genus: the green iguana , which is widespread throughout its range and a popular pet; and the Lesser Antillean iguana , which is native to the Lesser Antilles . Genetic analysis indicates that the green iguana may comprise a complex of multiple species, some of which have been recently described, but the Reptile Database considers all of these as subspecies of the green iguana. The word "iguana"

5733-450: The high proportion of fast-twitch, glycolytic muscle fibers (type A). These A fibers are not very vascularized and are low in myoglobin , giving them their pale look. This high density of A fibers allows iguanas to move very quickly for a short period of time, which facilitates short bursts of movement, but is inefficient for long duration movement, since cellular respiration in A fibers is anaerobic . Several species of lizards, including

5824-470: The highest number of chromosomes (164–174) among vertebrates. Due to certain peculiarities in their adaptive immune system , the study of lampreys provides valuable insight into the evolution of vertebrate adaptive immunity. Generated from a somatic recombination of leucine-rich repeat gene segments, lamprey leukocytes express surface variable lymphocyte receptors (VLRs). This convergently evolved characteristic allows them to have lymphocytes that work as

5915-588: The iguanas, have a pale scale towards the back of their heads marking the parietal eye . This organ is sensitive to changes in illumination and sends signals to the pineal gland noting the change between day and night. A photopigment commonly found in the lamprey , known as parapinopsin, is also found in the iguana, and is sensitive to ultraviolet light and aids in the signaling between day and night. Iguanas have developed an herbivorous lifestyle, foraging exclusively on vegetation and foliage. To acquire, process, and digest plant matter, herbivorous lizards must have

6006-428: The jaws of juvenile lampreys, a muscular flap-like structure called the velum is present, which serves to generate a water current towards the mouth opening, which enables feeding and respiration. The unique morphological characteristics of lampreys, such as their cartilaginous skeleton , suggest they are the sister taxon (see cladistics ) of all living jawed vertebrates ( gnathostomes ). They are usually considered

6097-515: The lamprey loses both the gallbladder and the biliary tract , and the endostyle turns into a thyroid gland. Some species, including those that are not carnivorous and do not feed even following metamorphosis, live in freshwater for their entire lifecycle, spawning and dying shortly after metamorphosing. In contrast, many species are anadromous and migrate to the sea, beginning to prey on other animals while still swimming downstream after their metamorphosis provides them with eyes, teeth, and

6188-633: 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,

6279-436: The largest species, the sea lamprey having a maximum body length of around 1.2 metres (3.9 ft). Lacking paired fins , adult lampreys have one nostril atop the head and seven gill pores on each side of the head. The brain of the lamprey is divided into the telencephalon , diencephalon , midbrain , cerebellum , and medulla . Lampreys have been described as the only living vertebrates to have four eyes, having

6370-606: The lateral region of the neck among smaller, overlapping scales. The scales on the dorsal trunk of their bodies are also thicker and more tightly packed than those on the ventral sides. These scales may be a variety of colors and are not always visible from close distances. They have a large, round scale on their cheeks known as a subtympanic shield. Iguanas have keen vision and can see shapes, shadows, colors, and movement at long distances. Their visual acuity enables them to navigate through crowded forests and to locate food. They employ visual signals to communicate with other members of

6461-444: The length of its body as an adult. These markings can also sometimes be used to determine what stage of the life cycle the lamprey is in; G. australis individuals lose these stripes when they approach the reproductive phase and begin to travel upstream. Another example is Petromyzon marinus , which shifts to more of an orange color as it reaches the reproductive stage in its life cycle. Northern lampreys ( Petromyzontidae ) have

6552-444: 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. Lamprey Lampreys / ˈ l æ m p r eɪ z / (sometimes inaccurately called lamprey eels ) are a group of jawless fish comprising the order Petromyzontiformes / ˌ p ɛ t r oʊ m ɪ ˈ z ɒ n t ɪ f ɔːr m iː z / . The adult lamprey

6643-403: 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

6734-468: The most basal group of the Vertebrata . Instead of true vertebrae, they have a series of cartilaginous structures called arcualia arranged above the notochord. Hagfish , which resemble lampreys, have traditionally been considered the sister taxon of the true vertebrates (lampreys and gnathostomes) but DNA evidence suggests that they are in fact the sister taxon of lampreys. The heart of the lamprey

6825-428: 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

6916-485: The non-carnivorous species do not feed; they live on reserves acquired as ammocoetes. Lampreys live mostly in coastal and fresh waters and are found in most temperate regions. Some species (e.g. Geotria australis , Petromyzon marinus , and Entosphenus tridentatus ) travel significant distances in the open ocean, as evidenced by their lack of reproductive isolation between populations. Other species are found in land-locked lakes. Their larvae ( ammocoetes ) have

7007-488: The parapineal organ. One of the key physical components to the lamprey are the intestines , which are located ventral to the notochord . Intestines aid in osmoregulation by intaking water from its environment and desalinating the water they intake to an iso-osmotic state with respect to blood, and are also responsible for digestion . Studies have shown that lampreys are among the most energy-efficient swimmers. Their swimming movements generate low-pressure zones around

7098-541: 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

7189-425: The respiration of the organism. The final chordate synapomorphy is the post anal tail, which is muscular and extends behind the anus. Oftentimes adult amphioxus and lamprey larvae are compared by anatomists due to their similarities. Similarities between adult amphioxus and lamprey larvae include a pharynx with pharyngeal slits, a notochord, a dorsal hollow nerve cord and a series of somites that extend anterior to

7280-470: 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

7371-477: The same species. The tympanum , the iguana's eardrum , is located above the subtympanic shield (or "ear shield") behind each eye. Iguanas are often hard to spot, as they tend to blend into their surroundings, and their coloration enables them to hide from larger predators. Like most reptiles , an iguana has a three-chambered heart with two atria, one ventricle, and two aortae with a systemic circulation . The muscles of an iguana are very light in color due to

7462-408: 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

7553-497: 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,

7644-412: 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

7735-467: The strength of the skull allows for increased muscle presence and increases the ability of the skull to withstand stronger forces. Furthermore, the teeth of the iguana are acrodontal , meaning that their teeth sit on top of the surface of the jaw bone and project upwards. The teeth themselves are small and serrated - designed to grasp and shear food. Male iguanas, like other male examples of Squamata , have two hemipenes . During copulation, one hemipenis

7826-403: 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

7917-506: The taxonomy of the genus Iguana as follows, with I. delicatissima being the most basal member of the group. The species are classified as subspecies based on the ReptileDatabase definitions. Sauromalus I. delicatissima " I. i. rhinolopha " I. i. insularis I. i. sanctaluciae I. i. melanoderma I. i. iguana The Reptile Database synonymizes I. rhinolopha with I. iguana , only considering it

8008-441: The teeth on the oral disc in the excision of tissue. As a result, the flesh-feeders have smaller buccal glands as they do not require the production of anticoagulant continuously and mechanisms for preventing solid material entering the branchial pouches, which could otherwise potentially clog the gills. A study of the stomach content of some lampreys has shown the remains of intestines, fins and vertebrae from their prey. Close to

8099-543: The timing of the last common ancestor of all living lampreys, with some suggesting a Middle Jurassic date, around 175 million years ago, while other studies have suggested a younger split, dating to the Late Cretaceous. The older date study posited that the Northern and Southern Hemisphere lampreys diverged as part of the breakup of Pangea , while the Late Cretaceous study suggested that modern lampreys emerged in

8190-576: 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

8281-429: 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

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