Reptiles generally reproduce sexually, though some are capable of asexual reproduction. All reproductive activity occurs through the cloaca, the single exit/entrance at the base of the tail where waste is also eliminated. Most reptiles have copulatory organs, which are usually retracted or inverted and stored inside the body. In turtles and crocodilians, the male has a single median penis, while squamates, including snakes and lizards, possess a pair of hemipenes, only one of which is typically used in each session. Tuatara, however, lack copulatory organs, and so the male and female simply press their cloacas together as the male discharges sperm.
Reproduction
Reptile
Reptile | Reproduction
Reptiles generally reproduce sexually; Most reptiles lay amniotic eggs They generally reproduce sexually They generally reproduce sexually, though some are capable of asexual reproduction. They generally reproduce sexually, though some are capable of asexual reproduction.
hypothalamic amenorrhea will result in the increased secretion of thyroid stimulating hormone (tsh)
user
Sorry. I cannot find the answer based on the context.
assistant
what is hypopituitarism?
user
A decreased ("hypo") secretion of one or more of the eight hormones normally produced by the pituitary gland at the base of the brain.
assistant
what are the indications of it?
user
Insufficiency of follicle-stimulating hormone (FSH) and/or luteinizing hormone (LH) leading to sex hormone abnormalities. Growth hormone deficiency is more common in people with an underlying tumor than those with other causes.
assistant
how this can be treated?
user
Removing the underlying cause, treating the hormone deficiencies, and addressing any other repercussions that arise from the hormone deficiencies.
assistant
you mentioned a gland above, where is it located in human body?
user
The bottom of the hypothalamus at the base of the brain.
assistant
what is the size of this gland?
user
The size of a pea
assistant
what is the functions of anterior lobe of this gland?
user
Synthesizes and secretes hormones; regulates several physiological processes including stress, growth, reproduction, and lactation.
assistant
which hormones are synthesized by this lobe?
user
Growth hormone, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), thyroid stimulating hormone (TSH) etc
assistant
how is the posterior lobe different from the anterior lobe?
user
It store and secretes (but does not synthesize) the important endocrine hormones.
assistant
in which other animals this gland can be found?
user
All vertebrates such as mammals, amphibians, reptiles, and birds,
assistant
what is the clinical significance of this gland?
user
There are diseases involving the pituitary gland. The functions of the pituitary gland can be adversely affected by an over- or under-production of associated hormones. The Pituitary gland growth during adolescence can be altered by early life stress such as childhood maltreatment or maternal dysphoric behavior.
assistant
what is the third mentioned vertebrates from the above list?
user
They are tetrapod animals in the class Reptilia, comprising today's turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, and their extinct relatives
assistant
do they play any roles in cultures and religions?
user
Yes - In Egyptian history, the Nile cobra was worshipped as one of the gods and was also used for sinister purposes; In Hinduism, snakes are worshipped as gods; The turtle has a symbol of steadfastness and tranquility in religion, mythology, and folklore from around the world.
assistant
what  type of reproduction is common in this class?
user
Reptiles generally reproduce sexually, though some are capable of asexual reproduction. All reproductive activity occurs through the cloaca, the single exit/entrance at the base of the tail where waste is also eliminated. Most reptiles have copulatory organs, which are usually retracted or inverted and stored inside the body. In turtles and crocodilians, the male has a single median penis, while squamates, including snakes and lizards, possess a pair of hemipenes, only one of which is typically used in each session. Tuatara, however, lack copulatory organs, and so the male and female simply press their cloacas together as the male discharges sperm.
Reptile | Reproduction
Asexual reproduction has been identified in squamates in six families of lizards and one snake. In some species of squamates, a population of females is able to produce a unisexual diploid clone of the mother. This form of asexual reproduction, called parthenogenesis, occurs in several species of gecko, and is particularly widespread in the teiids (especially "Aspidocelis") and lacertids ("Lacerta"). In captivity, Komodo dragons (Varanidae) have reproduced by parthenogenesis.
Reptile | Reproduction
Parthenogenesis is a natural form of reproduction in which growth and development of embryos occur without fertilization. Reproduction in squamate reptiles is ordinarily sexual, with males having a ZZ pair of sex determining chromosomes, and females a ZW pair. However, various species, including the Colombian Rainbow boa ("Epicrates maurus"), "Agkistrodon contortrix" (copperhead snake) and "Agkistrodon piscivorus" (cotton mouth snake) can also reproduce by facultative parthenogenesis—that is, they are capable of switching from a sexual mode of reproduction to an asexual mode—resulting in production of WW female progeny. The WW females are likely produced by terminal automixis. Mole salamanders are an ancient (2.4–3.8 million year-old) unisexual vertebrate lineage.
Vertebrate | Parthenogenesis
This is also the only reptile group in which both viviparous and ovoviviparous species are found, as well as the usual oviparous reptiles. Some species, such as the Komodo dragon, can reproduce asexually through parthenogenesis. There have been studies on how sexual selection manifests itself in snakes and lizards. Snakes use a variety of tactics in acquiring mates. Ritual combat between males for the females they want to mate with includes topping, a behavior exhibited by most viperids, in which one male will twist around the vertically elevated fore body of its opponent and forcing it downward. It is common for neck biting to occur while the snakes are entwined.
Squamata | Reproduction
In the latter group, many species, including all boas and most vipers, utilize this mode of reproduction. The degree of viviparity varies; some species simply retain the eggs until just before hatching, others provide maternal nourishment to supplement the yolk, and yet others lack any yolk and provide all nutrients via a structure similar to the mammalian placenta. The earliest documented case of viviparity in reptiles is the Early Permian mesosaurs, although some individuals or taxa in that clade may also have been oviparous because a putative isolated egg has also been found. Several groups of Mesozoic marine reptiles also exhibited viviparity, such as mosasaurs, ichthyosaurs, and Sauropterygia, a group that include pachypleurosaurs and Plesiosauria.
Reptile | Reproduction
piscivorus" appear to be capable of this form of parthenogenesis. Reproduction in squamate reptiles is almost exclusively sexual. Males ordinarily have a ZZ pair of sex determining chromosomes, and females a ZW pair. However, the Colombian Rainbow boa ("Epicrates maurus") can also reproduce by facultative parthenogenesis resulting in production of WW female progeny. The WW females are likely produced by terminal automixis.
Snake | Facultative parthenogenesis
Because the oviparous species reproduce less frequently, these traits may have been selected to generate stronger propulsions, develop more mitochondria and increase the amount of sperm per ejaculate to help aid in the sperms success rate. Often in snake species, females will copulate with multiple males in one mating aggregation. To increase his chances in paternity, a male will sometimes try to inhibit the female from re-mating. A common tactic in many species is to obstruct the reproductive pathway of the female in order to physically prevent additional copulations. The mating plug of "T.s. parietalis" is a jellylike blob produced by males that is implanted within the females reproductive tract.
Sexual selection in scaled reptiles | In snakes
In some of the "Cnemidophorus" species, there are no males, and they reproduce through parthenogenesis. This is well known in bees and aphids, but is very rare in vertebrates. Those species without males are now known to originate through hybridization, or interspecific breeding. Occasionally, a mating between a female of one species and a male of another produces a parthenogen, a female that is able to produce viable eggs that are genetically identical to her own cells. The lizards that hatch from these eggs are thus also parthenogens that can again produce identical eggs, resulting in an asexual, clonal population.
Cnemidophorus | Reproduction
Reproduction in snakes is almost exclusively sexual. Males ordinarily have a ZZ pair of sex determining chromosomes and females a ZW pair. However, it was recently shown that "E. maurus" is capable of reproducing by facultative parthenogenesis resulting in production of WW female progeny. The WW females were likely produced by terminal automixis (see diagram), a type of parthenogenesis in which two terminal haploid products of meiosis fuse to form a zygote, which then develops into a daughter progeny. This is only the third genetically confirmed case of consecutive virgin births of viable offspring from a single female within any vertebrate lineage.
Epicrates maurus | Parthenogenesis
Asexual reproduction is found in nearly half of the animal phyla. Parthenogenesis occurs in the hammerhead shark and the blacktip shark. In both cases, the sharks had reached sexual maturity in captivity in the absence of males, and in both cases the offspring were shown to be genetically identical to the mothers. The New Mexico whiptail is another example. Some reptiles use the ZW sex-determination system, which produces either males (with ZZ sex chromosomes) or females (with ZW or WW sex chromosomes). Until 2010, it was thought that the ZW chromosome system used by reptiles was incapable of producing viable WW offspring, but a (ZW) female boa constrictor was discovered to have produced viable female offspring with WW chromosomes.
Asexual reproduction | Examples in animals
Turtle "Shetyw", "Shetw", "Sheta", "shtyw" was common in Ancient Egyptian Art (especially Predynastic and Old Kingdom art). Turtle fossils are the most common reptiles found in the Fayoum, including "Gigantochersina ammon", a tortoise as large as those living on the Galapagos Islands today. Charles Andrews was the first to write in the West about these tortoises in the early 20th century. Predynastic slate palettes represent freshwater (soft carapace, "Trionyx triunguis") turtles as does the hieroglyph for "turtle" in which the chelonian is always represented from above. Zoomorphic palettes were commonly made in the shapes of turtles. A stone vase in the form of a turtle was found in Naqada.
Cultural depictions of turtles | Ancient Egypt
Male turtles and crocodiles have a penis, while male specimens of the reptile order Squamata have two paired organs called hemipenes. Tuataras must use their cloacae for reproduction. Due to evolutionary convergence, turtle and mammal penises have a similar structure. In some fish, the gonopodium, andropodium, and claspers are intromittent organs (to introduce sperm into the female) developed from modified fins.
Penis | Other vertebrates
"M. reuteri" is oviparous.
Reuter's blind snake | Reproduction
Another mechanism typically observed in facultative parthenote reptiles is terminal fusion, in which a haploid polar body produced as a byproduct of normal female meiosis fuses with the egg cell to form a diploid nucleus, much as a haploid sperm cell fuses its nucleus with that of an egg cell to form a diploid genome during sexual reproduction. This method of parthenogenesis produces offspring that are homozygous at nearly all genetic loci, and inherit approximately half of their mother's genetic diversity. This form of parthenogenesis can produce male as well as WW-genotype females. Because the meiosis process proceeds normally in species employing this mechanism, they are capable of both sexual and asexual reproduction, as in the Komodo dragon and several species of snakes.
Parthenogenesis in squamata | Half-cloning
"A. quadrivirgatum" is oviparous.
Middle American burrowing snake | Reproduction
Reptiles are almost all sexually dimorphic, and exhibit internal fertilization through the cloaca. Some reptiles lay eggs while others are ovoviviparous (animals that deliver live young). Reproductive organs are found within the cloaca of reptiles. Most male reptiles have copulatory organs, which are usually retracted or inverted and stored inside the body. In turtles and crocodilians, the male has a single median penis-like organ, while male snakes and lizards each possess a pair of penis-like organs.
Reproductive system | Reptiles
Snake sperm morphology and function is highly influenced by their ability to find, interact with, and fertilize eggs. Snake species display extended copulations and higher gonad mass/body mass proportions in males than other reptilian taxonomic groups. Furthermore, their mating systems have a wide range of variability, depending on the temporal availability and predictability of the females. These factors influence sperm competition levels in both intense male-male combative species and those species that participate in prolonged mate searching. Oviparous species show relatively larger testes and sperm midpiece length than viviparous species because oviparous species often reproduce annually as opposed to the bi annual cycle of the viviparous species.
Sexual selection in scaled reptiles | In snakes
After killing her, Perseus gave her head to Athena who fixed it to her shield called the Aegis. The Titans are depicted in art with their legs replaced by bodies of snakes for the same reason: They are children of Gaia, so they are bound to the earth. In Hinduism, snakes are worshipped as gods, with many women pouring milk on snake pits. The cobra is seen on the neck of Shiva, while Vishnu is depicted often as sleeping on a seven-headed snake or within the coils of a serpent. There are temples in India solely for cobras sometimes called "Nagraj" (King of Snakes), and it is believed that snakes are symbols of fertility.
Reptile | In cultures and religions
Ovoviviparous. Producing 1-15 live young at a time, measuring 105-191mm.
Ceylonese cylinder snake | Reproduction
As well as the serpent, the Nile crocodile was another important reptile in Ancient Egyptian religion. Several deities were depicted in crocodilian form, but the most famous and important of these was undoutedly the god Sobek. Sobek was a powerful and fearsome god, associated with violence and strength, and acted as a fierce protector against evil, and a punisher of wrongdoers. It is easy to see why he was associated with the crocoodile, which similarly is a very fearsome creature. Sobek also had a role relating to fertility, particularly the fertility brought to the land by the Nile flood, in whose waters crocodiles live.
Animal worship | Other reptiles
A captive Egyptian mongoose was over 20 years old. Its generation length is 7.5 years.
Egyptian mongoose | Reproduction
contortrix" and "A. piscivorus" appear to be capable of this form of parthenogenesis. Reproduction in squamate reptiles is ordinarily sexual, with males having a ZZ pair of sex determining chromosomes, and females a ZW pair. However, the Colombian Rainbow boa, "Epicrates maurus", can also reproduce by facultative parthenogenesis resulting in production of WW female progeny. The WW females are likely produced by terminal automixis.
Squamata | Facultative parthenogenesis
In "stunted" newly mature females from Lake Turkana measuring , the average clutch size was only 15. Graham and Beard (1968) hypothesized that, while females do continue to grow as do males throughout life, that past a certain age and size that females much over in length in Lake Turkana no longer breed (supported by the physiology of the females examined here); however, subsequent studies in Botswana and South Africa have found evidence of nesting females at least in length. In the Olifants River in South Africa, rainfall influenced the size of nesting females as only larger females (greater than ) nested during the driest years.
Nile crocodile | Reproduction
s. parietalis"). Generally, populations include far more males than females, so during mating season, they form "mating balls", where one or two females are completely swamped by 10 or more males. Sometimes, a male snake mates with a female before hibernation, and the female stores the sperm internally until spring, when she allows her eggs to be fertilized. If she mates again in the spring, the fall sperm degenerate, and the spring sperm fertilize her eggs. The females may give birth ovoviviparously to 12 to 40 young from July through October.
Common garter snake | Reproduction
However, stunted sexual maturity appears to occur in populations at opposite extremes, both where crocodiles are thought to be overpopulated and where they are overly reduced to heavy hunting, sometimes with females laying eggs when they measure as small as although it is questionable whether such clutches would bear healthy hatchlings. According to Bourquin (2008), the average breeding female in southern Africa is between . Earlier studies support that breeding is often inconsistent in females less than and clutch size is smaller, a female at reportedly never lays more than 35 eggs, while a female measuring can expect a clutch of up to 95 eggs.
Nile crocodile | Reproduction
For example, males are often wounded in the process of defending their territory from hyenas and other males.
Common tsessebe | Breeding and reproduction
This species reproduces sexually. The male has a penis in the middle, or at least close to the middle, of his head. The female has a series of translucent glands the lead to a seminal receptacle, where an egg waits for the semen.
Assiminea grayana | Reproduction
Females produce a pheromone to attract males, which engage in neck-wrestling combat dances. A female in Malindi was followed by seven males. They give birth to large numbers of offspring; litters over 80 have been reported, while 50–60 are not unusual. Newborns are 12.5–17.5 cm in length. Very large specimens, particularly those from East Africa, give birth to the highest numbers of offspring. A Kenyan female in a Czech zoo gave birth to 156 young, the largest litter for any species of snake.
Puff adder | Reproduction
In 2012, facultative parthenogenesis was reported in wild vertebrates for the first time by US researchers amongst captured pregnant copperhead and cottonmouth female pit-vipers. The Komodo dragon, which normally reproduces sexually, has also been found able to reproduce asexually by parthenogenesis. A case has been documented of a Komodo dragon reproducing via sexual reproduction after a known parthenogenetic event, highlighting that these cases of parthenogenesis are reproductive accidents, rather than adaptive, facultative parthenogenesis. Some reptile species use a ZW chromosome system, which produces either males (ZZ) or females (ZW). Until 2010, it was thought that the ZW chromosome system used by reptiles was incapable of producing viable WW offspring, but a (ZW) female boa constrictor was discovered to have produced viable female offspring with WW chromosomes.
Parthenogenesis | Squamata
Parthenogenesis is a natural form of reproduction in which growth and development of embryos occur without fertilization. "Agkistrodon contortrix" (copperhead) and "Agkistrodon piscivorus" (cotton mouth) can reproduce by facultative parthenogenesis. That is, they are capable of switching from a sexual mode of reproduction to an asexual mode. The type of parthenogenesis that likely occurs is automixis with terminal fusion, a process in which two terminal products from the same meiosis fuse to form a diploid zygote. This process leads to genome wide homozygosity, expression of deleterious recessive alleles and often to developmental abnormalities. Both captive-born and wild-born "A. contortrix" and "A.
Snake | Facultative parthenogenesis
"P. chamissonis" is an oviparous reptile.
Philodryas chamissonis | Reproduction
Reptiles are tetrapod animals in the class Reptilia, comprising today's turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, and their extinct relatives. The study of these traditional reptile orders, historically combined with that of modern amphibians, is called herpetology. Because some reptiles are more closely related to birds than they are to other reptiles (e.g., crocodiles are more closely related to birds than they are to lizards), the traditional groups of "reptiles" listed above do not together constitute a monophyletic grouping or clade (consisting of all descendants of a common ancestor). For this reason, many modern scientists prefer to consider the birds part of Reptilia as well, thereby making Reptilia a monophyletic class, including all living diapsids.
Reptile | Introduction
"Pteronotus quadridens" are monoesturous and uniparous most of the time with twinning rarely occurring. Based on the testicular size, mating begins in January and most females are pregnant in May. The pregnant female undergoes an increase in body mass of 38%. The largest embryo reported weighed 1.8 g, or 30.2% of the female’s body mass. Throughout the breeding season, either males or females might disappear completely for the caves. However, there was a marked shift in adult sex ratio favoring females. These evidences suggest sexual segregation during maternity period.
Sooty mustached bat | Mating and reproduction
The general build was heavy in all forms, though otherwise very similar to that of early reptiles. The skin, at least in the more advanced forms probably had a water-tight epidermal horny overlay, similar to the one seen in today's reptiles, though they lacked horny claws. In chroniosuchians and some seymouriamorphs, like "Discosauriscus", dermal scales are found in post-metamorphic specimens, indicating they may have had a "knobbly", if not scaly, appearance. Seymouriamorphs reproduced in amphibian fashion with aquatic eggs that hatched into larvae (tadpoles) with external gills; it is unknown how other tetrapods traditionally assigned to Reptiliomorpha reproduced.
Reptiliomorpha | Physiology
In reptiles, the cloaca consists of the "urodeum", "proctodeum", and "coprodeum". Some species have modified cloacae for increased gas exchange (see Reptile respiration and Reptile reproduction). This is where reproductive activity occurs.
Cloaca | Reptiles
Pharaoh cuttlefish reproduce similarly to most other cuttlefish. Large males compete in combat until a victor is decided, although it is often decided without any initiation of physical combat. The males circle each other performing threatening displays of color and tentacles until one male swims off in defeat. The victorious male then mates with females by grabbing them with their tentacles, turning the female so that the two animals are face-to-face, then using a specialized tentacle to insert sperm sacs into an opening near the female's mouth. The male then guards the female until she lays the fertilized eggs a few hours later.
Pharaoh cuttlefish | Reproduction
Breeding females along the Olifants were overall larger than those in Zimbabwe. Most females nest only every two to three years while mature males may breed every year. During the mating season, males attract females by bellowing, slapping their snouts in the water, blowing water out of their noses, and making a variety of other noises. Among the larger males of a population, territorial clashes can lead to physical fighting between males especially if they are near the same size. Such clashes can be brutal affairs and can end in mortality but typically end with victor and loser still alive, the latter withdrawing into deep waters.
Nile crocodile | Reproduction
Adult males are slightly larger and more muscular than females, and have wider heads and necks. Visual sex determination can, however, be difficult, since the penis and testes are located internally between the rectum and urinary bladder in males and females have a single pair of mammae near the armpits. Fertilization occurs by contact transfer without intromission, similar to some lizards. Polygynous mating usually results in a single offspring; twins are possible but rare. The large foreclaws prevent mothers from grasping their newborns and they therefore have to carry the offspring until they are self-sufficient.
Anteater | Reproduction
As the plates and spikes would have been obstacles during copulation, it is possible that pairs mated back-to-back with the female staying still in a lordosis posture as the male manoeuvres this penis into her cloaca. The shoulder spikes would have made the female unable to lay on her side during mating as is proposed for "Stegosaurus".
Kentrosaurus | Reproduction
This fusion produces the interparietal bone, which is inherited by mammals. Postparietals are common in extinct amphibians and early reptiles. However, most living amphibians (of the group Lissamphibia) and living reptiles (of the group Sauria) lack postparietal bones, with a few exceptions.
Postparietal | Introduction
"T. sumichrasti" is viviparous.
Sumichrast's garter snake | Reproduction
In the 13th century the category of "reptile" was recognized in Europe as consisting of a miscellany of egg-laying creatures, including "snakes, various fantastic monsters, lizards, assorted amphibians, and worms", as recorded by Vincent of Beauvais in his "Mirror of Nature". In the 18th century, the reptiles were, from the outset of classification, grouped with the amphibians. Linnaeus, working from species-poor Sweden, where the common adder and grass snake are often found hunting in water, included all reptiles and amphibians in class "III – Amphibia" in his "Systema Naturæ". The terms "reptile" and "amphibian" were largely interchangeable, "reptile" (from Latin "repere", 'to creep') being preferred by the French.
Reptile | Research history
Once a female has been attracted, the pair warble and rub the undersides of their jaws together. Compared to the tender behaviour of the female accepting the male, copulation is rather rough (even described as "rape"-like by Graham & Beard (1968)) in which the male often roars and pins the female underwater. Cott noted little detectable discrepancy in the mating habits of Nile crocodiles and American alligators. In some regions, males have reportedly mated with several females, perhaps any female that enters his claimed territory, though in most regions annual monogamy appears to be most common in this species. Females lay their eggs about one to two months after mating.
Nile crocodile | Reproduction
"A. versteegii" is oviparous.
Arthrosaura versteegii | Reproduction
The cleithrum disappeared early in the evolution of reptiles, and is not found in any living amniotes, but the interclavicle is present in most modern reptiles, and also in monotremes. In modern forms, however, there are a number of variations from the primitive pattern. For example, crocodilians and salamanders lack clavicles altogether (although crocodilians do retain the interclavicle), while in turtles, they form part of the armoured plastron. The interclavicle is absent in marsupials and placental mammals. In many mammals, the clavicles are also reduced, or even absent, to allow the scapula greater freedom of motion, which may be useful in fast-running animals.
Clavicle | Other animals
This mechanism is found across the animal kingdom, from Lepidoptera to Squamata. In snakes and lizards, morphological differences in the reproductive organs are believed to exist to help the male copulate with the female. Spikes and hooks are thought to assist the male in fixing the hemipenis in place during mating, and are made specifically compatible to the female of the species. For example, species with branched hemipenes have females with branched cloacas, and species with many spikes have females with thicker cloacal walls, compared to those of species with males having little or no spines. This huge variety among the reproductive organs of squamata is of interest to taxonomists, as it may be able to shed light on evolutionary relationships among reptiles.
Hemipenis | Lock-and-key mechanism
Males in this category resort to using courtship displays in an attempt to gain mating access to a female.
Turtle | Reproduction
"Medauroidea extradentata" is mainly parthenogenetic, meaning they are asexual, making males very rare in the species. The female drops hundreds of eggs onto the forest floor, these eggs hatch in a few months. The eggs of this species are mottled with black and white and capped with black.
Medauroidea extradentata | Reproduction
The incident was reported along with a photo of the dead reptile in 'Aaj' Urdu language newspaper published from the provincial capital Peshawar on September 10, 2019. Originally, the type locality was listed only as "Oriente." However, Flower (1933) proposed "Egypt" by way of clarification.
Cerastes cerastes | Distribution and habitat
They may be capable of delayed fertilization; (parthenogenesis is rare but not unknown in snakes) as a female in the London zoo kept in isolation from August, 1885 gave birth in August, 1888.
Ahaetulla nasuta | Description
"D. humayuni" is oviparous.
Dendrelaphis humayuni | Reproduction
"Z. lineatus" is oviparous.
Italian Aesculapian snake | Reproduction
2)Edmonds, D., Kessler, E. and Bolte, L. (2019), How common is common? Rapidly assessing population size and structure of the frog Mantidactylus betsileanus at a site in east‐central Madagascar. Austral Ecology
Mantidactylus betsileanus | References
Parthenogenesis is a mode of asexual reproduction in which offspring are produced by females without the genetic contribution of a male. Among all the sexual vertebrates, the only examples of true parthenogenesis, in which all-female populations reproduce without the involvement of males, are found in squamate reptiles (snakes and lizards). There are about 50 species of lizard and 1 species of snake that reproduce solely through parthenogenesis (obligate parthenogenesis). It is unknown how many sexually reproducing species are also capable of parthenogenesis in the absence of males (facultative parthenogenesis), but recent research has revealed that this ability is widespread among squamates.
Parthenogenesis in squamata | Introduction
"A. arabicus" is oviparous.
Acanthodactylus arabicus | Reproduction
During mating, the male katuali wraps itself around the female until she is fertilized. Because the eggs would not survive in water, the female swims into a sea cave to lay the eggs in dry crevices. These eggs take six months to hatch, and then the infant snakes make their way to the ocean.
Katuali | Reproduction
Another can be found in the Museum of Science and Technology in Islam in the King Abdullah University of Science and Technology in Saudi Arabia.
Elephant clock | Modern reproductions
In all reptiles the urinogenital ducts and the anus both empty into an organ called a cloaca. In some reptiles, a midventral wall in the cloaca may open into a urinary bladder, but not all. It is present in all turtles and tortoises as well as most lizards, but is lacking in the monitor lizard, the legless lizards. It is absent in the snakes, alligators, and crocodiles. Many turtles, tortoises, and lizards have proportionally very large bladders. Charles Darwin noted that the Galapagos tortoise had a bladder which could store up to 20% of its body weight. Such adaptations are the result of environments such as remote islands and deserts where water is very scarce.
Reptile | Excretion
Other art representations of turtles in Ancient Egypt were common. The earliest representations of the Nile turtle date back to pre-dynastic times and were associated with magical significance that was meant to ward off evil. Amulets and objects with depictions of the turtles represent the turtle as a force to defend health and life.
Cultural depictions of turtles | Ancient Egypt
The teeth are merely projections of bony material from the jaw and eventually wear down. The brain and heart are more primitive than those of other reptiles, and the lungs have a single chamber and lack bronchi. The tuatara has a well-developed parietal eye on its forehead.
Anatomy | Reptile anatomy
"C. thirakhupti" is oviparous.
Thirakhupt's bent-toed gecko | Reproduction
Ritual combat between males for the females they want to mate with includes topping, a behavior exhibited by most viperids in which one male will twist around the vertically elevated fore body of its opponent and forcing it downward. It is common for neck biting to occur while the snakes are entwined.
Snake | Reproduction
On average, sexual maturity is obtained from 12 to 16 years of age. For males, the onset of sexual maturity occurs when they are about long and mass of , being fairly consistent. On the other hand, that for females is rather more variable, and may be indicative of the health of a regional population based on size at sexual maturity. On average, according to Cott (1961), female sexual maturity occurs when they reach in length. Similarly, a wide range of studies from southern Africa found that the average length for females at the onset of sexual maturity was .
Nile crocodile | Reproduction
Females are polyestrous and can raise several litters a year; in captivity, breeding takes place year-round.
Common planigale | Reproduction
"S. monachus" is viviparous.
Monk snake | Reproduction
Most reptiles of the squamatan order (lizards and snakes) reproduce sexually, but parthenogenesis has been observed to occur naturally in certain species of whiptails, some geckos, rock lizards, Komodo dragons and snakes. Some of these like the mourning gecko "Lepidodactylus lugubris", Indo-Pacific house gecko "Hemidactylus garnotii", the hybrid whiptails "Cnemidophorus", Caucasian rock lizards "Darevskia", and the brahminy blindsnake, "Indotyphlops braminus" are unisexual and obligately parthenogenetic. Other reptiles, such as the Komodo dragon, other monitor lizards, and some species of boas, pythons, filesnakes, gartersnakes and rattlesnakes were previously considered as cases of facultative parthenogenesis, but are in fact cases of accidental parthenogenesis.
Parthenogenesis | Squamata
Most "Echis" species, such as those found in Africa, are oviparous, while others, such as those in India, are viviparous.
Echis | Reproduction
"M. braccianii" is oviparous.
Scortecci's blind snake | Reproduction
The species is oviparous, with females laying 10–50 eggs at a time. Afterward, females coil around the eggs to protect them and keep them warm through using muscular contractions to generate heat. This type of maternal care, which is typical for pythons, ceases once the hatchlings have emerged.
Morelia spilota | Reproduction
This means reproduction occurs at two- to five-year intervals, the slowest in any reptile. Wild tuatara are known to be still reproducing at about 60 years of age; "Henry", a male tuatara at Southland Museum in Invercargill, New Zealand, became a father (possibly for the first time) on 23 January 2009, at the age of 111. The sex of a hatchling depends on the temperature of the egg, with warmer eggs tending to produce male tuatara, and cooler eggs producing females. Eggs incubated at have an equal chance of being male or female. However, at , 80% are likely to be males, and at , 80% are likely to be females; at all hatchlings will be females.
Tuatara | Reproduction
This class is a point of reference in social reproduction, comprising 15% to 20% of the U.S. population. The majority of those in the lower classes are minorities.
Social reproduction | Lower class
"T. dugandi" is oviparous.
Dugand's blind snake | Reproduction
The snake or serpent has played a powerful symbolic role in different cultures. In Egyptian history, the Nile cobra adorned the crown of the pharaoh. It was worshipped as one of the gods and was also used for sinister purposes: murder of an adversary and ritual suicide (Cleopatra). In Greek mythology snakes are associated with deadly antagonists, as a chthonic symbol, roughly translated as "earthbound". The nine-headed Lernaean Hydra that Hercules defeated and the three Gorgon sisters are children of Gaia, the earth. Medusa was one of the three Gorgon sisters who Perseus defeated. Medusa is described as a hideous mortal, with snakes instead of hair and the power to turn men to stone with her gaze.
Reptile | In cultures and religions
Examples of humans with animal heads (theriocephaly) in the ancient Egyptian pantheon include jackal-headed Anubis, cobra-headed Amunet, lion-headed Sekhmet, falcon-headed Horus, etc. Most of these deities also have a purely zoomorphic and a purely anthropomorphic aspect, with the hybrid representation seeking to capture aspects of both of which at once. Similarly, the Gaulish "Artio" sculpture found in Berne shows a juxtaposition of a bear and a woman figure, interpreted as representations of the theriomorphic and the anthropomorphic aspect of the same goddess. Non-human hybrids also appear in ancient Egyptian iconography as in Ammit (combining the crocodile, the lion, and the hippopotamus).
Hybrid beasts in folklore | Ancient Egypt
"A. tovelli" is oviparous.
Darwin blind snake | Reproduction
The existence of two sexes seems to have been selected independently across different evolutionary lineages (see convergent evolution). The repeated pattern is sexual reproduction in isogamous species with two or more mating types with gametes of identical form and behavior (but different at the molecular level) to anisogamous species with gametes of male and female types to oogamous species in which the female gamete is very much larger than the male and has no ability to move. There is a good argument that this pattern was driven by the physical constraints on the mechanisms by which two gametes get together as required for sexual reproduction.
Male | Overview
Reptiles are a class of animals comprising turtles, tuataras, lizards, snakes and crocodiles. They are tetrapods, but the snakes and a few species of lizard either have no limbs or their limbs are much reduced in size. Their bones are better ossified and their skeletons stronger than those of amphibians. The teeth are conical and mostly uniform in size. The surface cells of the epidermis are modified into horny scales which create a waterproof layer. Reptiles are unable to use their skin for respiration as do amphibians and have a more efficient respiratory system drawing air into their lungs by expanding their chest walls.
Anatomy | Reptile anatomy
Internal fertilization with many vertebrates (such as reptiles, some fish, and most birds) occur via cloacal copulation (see also hemipenis), while mammals copulate vaginally, and many basal vertebrates reproduce sexually with external fertilization. For primitive insects, the male deposits spermatozoa on the substrate, sometimes stored within a special structure; courtship involves inducing the female to take up the sperm package into her genital opening, but there is no actual copulation. In groups that have reproduction similar to spiders, such as dragonflies, males extrude sperm into secondary copulatory structures removed from their genital opening, which are then used to inseminate the female.
Sexual intercourse | Other animals
"P. tentoria" is oviparous.
Indian tent turtle | Reproduction
Motani "et alii" (2014) concluded that, because "Chaohusaurus" is a very basal form, this provided strong evidence that, at least originally, ichthyopterygian young were born with the head first. This early method might have later been changed because it resulted in a too high mortality. They also cited this as evidence for a terrestrial evolution of viviparity in the land-dwelling ancestors of ichthyosaurs. AGM I-1 in 2014 represented the oldest reptile viviparous birth known.
Chaohusaurus | Reproduction
These are viviparous snakes. About five to 25 young are produced at once.
Trimeresurus trigonocephalus | Reproduction
Males were discovered to contain a pair of XY sex determining chromosomes, while females have a XX pair. This is the first time snakes were thought to contain male heterogamety, and since then has been found in ball pythons ("Python regius") as well. During the breeding season, the female boa emits pheromones from her cloaca to attract males, which may then wrestle to select one to breed with her. During breeding, the male curls his tail around the female's and the hemipenes (or male reproductive organs) are inserted. Copulation can last from a few minutes to several hours and may occur several times over a few week period.
Boa constrictor | Reproduction and development
"A. masirae" is oviparous.
Acanthodactylus masirae | Reproduction
The Solomon Islands skink is one of the few species of reptile that lives in a communal group known as a circulus. The Solomon Islands skink reproduces by viviparous matrotrophy: the female provides a placenta for its young, which are born after a gestation period of six to eight months; this is a rare trait among reptiles. The newborn skink is of a large size compared to its mother; the northern Solomon Islands skinks are approximately in length and weigh , whereas the common Solomon Islands skinks are and when they are born. This reduced size disparity led the former curator of reptiles at the Philadelphia Zoo, Dr.
Solomon Islands skink | Reproduction
During courtship the pair trill and chatter and copulation can be quite a loud affair. After copulating she may remain with the male or the pair may separate and seek other mates. The females gives birth in her nest to a litter of between four and nine young, up to three times a year, if food supply allows.
Egyptian weasel | Reproduction
Female breeds in transient, rain-filled grass pools. The egg if the species are boat-shaped, with fragmented micropylar collar, and membrane-like wall enclosing many tubercles of exo-chorionic sculpture.
Aedes lineatopennis | Reproduction
"D. fasciata" is oviparous.
Central African egg-eating snake | Reproduction
"A. aegyptius" is oviparous.
Acanthodactylus aegyptius | Reproduction
In the annual Hindu festival of Nag Panchami, snakes are venerated and prayed to. In religious terms, the snake and jaguar are arguably the most important animals in ancient Mesoamerica. "In states of ecstasy, lords dance a serpent dance; great descending snakes adorn and support buildings from Chichen Itza to Tenochtitlan, and the Nahuatl word "coatl" meaning serpent or twin, forms part of primary deities such as Mixcoatl, Quetzalcoatl, and Coatlicue." In Christianity and Judaism, a serpent appears in Genesis to tempt Adam and Eve with the forbidden fruit from the Tree of Knowledge of Good and Evil. The turtle has a prominent position as a symbol of steadfastness and tranquility in religion, mythology, and folklore from around the world.
Reptile | In cultures and religions
Parthenogenesis is a natural form of reproduction in which growth and development of embryos occur without fertilization. "A. contortrix" can reproduce by facultative parthenogenesis, that is, they are capable of switching from a sexual mode of reproduction to an asexual mode. The type of parthenogenesis that likely occurs is automixis with terminal fusion, a process in which two terminal products from the same meiosis fuse to form a diploid zygote. This process leads to genome-wide homozygosity, expression of deleterious recessive alleles, and often to developmental failure (inbreeding depression). Both captive-born and wild-born "A. contortrix" snakes appear to be capable of this form of parthenogenesis.
Agkistrodon contortrix | Facultative parthenogenesis
Rinehart concluded that the gracile form was female and the robust form was male based on differences in the sacral vertebrae of the gracile form, which allowed for greater flexibility for egg laying. Further support for this position was provided by an analysis showing that each morph comprised 50% of the population, as would be expected in a 50/50 sex ratio. However, more recent research has found that "C. bauri" and "C. rhodesiensis" had highly variable growth between individuals, with some specimens being larger in their immature phase than smaller adults were when completely mature; this indicates that the supposed presence of distinct morphs is simply the result of individual variation.
Coelophysis | Growth and sexual dimorphism
"H. hippocrepis" is oviparous.
Horseshoe whip snake | Reproduction
Females exhibit fierce protective behavior around the time of birth; this protectiveness of young is a rare occurrence in reptiles but is shorter in duration when compared to the protective behavior exhibited by a typical mammal.
Solomon Islands skink | Reproduction
Alternatively, it may physically plug the female's gonophore. In either explanation, the spermatophore prevents the female from reproducing with another male. In essence, the use of a spermatophore is evolutionarily favorable because it increases the probability of the male's genetic code being transferred to subsequent generations by lessening potential competition from other males. Pharaoh ant copulation, like that of many social insects, is harmful to the female. The penis valve contains sharp teeth, which latch onto a thick, soft cuticular layer in the female. This method of copulation too has an evolutionary basis. The teeth ensure sex lasts long enough for sufficient sperm transfer.
Pharaoh ant | Reproduction
Assortative mating in animals has been observed with respect to body size and color. Size-related assortative mating is prevalent across many species of vertebrates and invertebrates. It has been found in the simultaneous hermaphrodites such as the land snail "Bradybaena pellucida". One reason for its occurrence can be reciprocal intromission (i.e. both individuals provide both male and female gametes during a single mating) that happens in this species. Therefore, individuals with similar body size pair up with one another to facilitate this exchange. Moreover, it is known that larger individuals in such hermaphroditic species produce more eggs, so mutual mate choice is another factor leading to assortative mating in this species.
Assortative mating | In non-human animals
A histologically distinct initial segment of the epididymis is widely observed in many species of reptiles and even as far back as sharks. A large initial segment is also present in the epididymis of the testicond monotreme echidna. Furthermore, the scrotal epididymis of metatherian and eutherian mammals nearly all exhibit an initial segment. Hence, the initial segment of the epididymis is well conserved in testicond vertebrates (reptiles, monotremes) and in scrotal metatherian and eutherian mammals (Figure 1). The status of the histologic middle segment of the epididymis in reptiles is incompletely defined (Figure 1A). Considering the wide variation in the anatomical structures of the four orders (Crocodilia, Sphenodontia, Squamata, Testudines) of reptilian epididymides and the paucity of histologic studies that correlate anatomical structure to histology, the evolution of the middle segment in reptiles, if present, remains to be delineated.
Epididymis evolution from reptiles to mammals | Trends in the evolution of the epididymis from testicond reptiles and monotremes to scrotal mammals
Reptiles have a large diversity of maternal behaviors that is very dependent on the species and the type of reproduction it displays. Most reptiles are viviparous, although oviparous reptiles do exist. Oviparous reptiles often display very little or no maternal behavior after the eggs have hatched, while viviparous reptiles typically exhibit more extensive maternal care. Nile crocodiles however, are the exception to this. The females exhibit maternal care behaviors that involve transporting their young in their mouths shortly after they have hatched, to the waters edge and remain with the young until they have reached further development
Maternal behavior in vertebrates | Reptiles
This species is usually considered amphidromous, a particular type of diadromy meaning that reproduction occurs in fresh water and larval growth occurs in the sea.
Common galaxias | Life history
"A. orientalis" is oviparous.
Acanthodactylus orientalis | Reproduction
Many cultures have legends of creatures which are part human and part reptile. One of the first historical depictions of a reptilian humanoid was the Ancient Egyptian deity Sobek, who had the head of a crocodile. He was depicted with similar traits, such as being aggressive and animalistic. In South Asian and Southeast Asian mythology, the Nāga are semi-divine creatures which are half-human and half-serpent.
Reptilian humanoid | In mythology