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Hemipenes
A hemipenis (: hemipenes) is one of a pair of intromittent organs of male squamates (snakes and lizards). Hemipenes are usually held inverted within the body, and are everted for reproduction via erectile tissue, much like that in the human penis. They come in a variety of shapes, depending on species, with ornamentation such as spikes. Background The hemipenis is the intromittent organ of Squamata, which is the second largest order of vertebrates with over 9,000 species distributed around the world. They differ from the intromittent organs of most other amniotes such as mammals, archosaurs and turtles that have a single genital tubercle, as squamates have paired, separate genitalia. Squamate hemipenes also develop from a different cell origin, originating from the same embryonic cells that produce the limbs, whereas mammalian penises arise from the embryonic cells that develop the tail. Evolution Much debate continues regarding the evolutionary origin of hemipenes and their rel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intromittent Organ
An intromittent organ is any external organ of a male organism that is specialized to deliver sperm during copulation. Intromittent organs are found most often in terrestrial species, as most non-mammalian aquatic species fertilize their eggs externally, although there are exceptions. For many species in the animal kingdom, the male intromittent organ is a hallmark characteristic of internal fertilization. Species with intromittent organs Invertebrates Molluscs Male cephalopods have a specialized arm, the hectocotylus, which is inserted into the female's mantle cavity to deliver a spermatophore during copulation. In some species, the hectocotylus breaks off inside the female's mantle cavity; in others, it can be used repeatedly to copulate with different females. Arachnids In spiders, the intromittent organs are the male pedipalps, even though these are not primarily sexual organs, but serve as indirect mating organs; in the male the pedipalps have hollow, clubbed tips, o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squamata
Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest Order (biology), order of reptiles; most members of which are commonly known as Lizard, lizards, with the group also including Snake, snakes. With over 11,991 species, it is also the second-largest order of Neontology, extant (living) vertebrates, after the Perciformes, perciform fish. Squamates are distinguished by their skins, which bear horny scale (zoology), scales or shields, and must periodically engage in molting. They also possess movable quadrate bones, making possible movement of the Maxilla, upper jaw relative to the neurocranium. This is particularly visible in snakes, which are able to open their mouths very widely to accommodate comparatively large prey. Squamates are the most variably sized living reptiles, ranging from the Sphaerodactylus ariasae, dwarf gecko (''Sphaerodactylus ariasae'') to the reticulated python (''Malayopython reticulatus''). The now-Extinction, extinct mosasaurs reached ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snake
Snakes are elongated limbless reptiles of the suborder Serpentes (). Cladistically squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales much like other members of the group. Many species of snakes have skulls with several more joints than their lizard ancestors and relatives, enabling them to swallow prey much larger than their heads ( cranial kinesis). To accommodate their narrow bodies, snakes' paired organs (such as kidneys) appear one in front of the other instead of side by side, and most only have one functional lung. Some species retain a pelvic girdle with a pair of vestigial claws on either side of the cloaca. Lizards have independently evolved elongate bodies without limbs or with greatly reduced limbs at least twenty-five times via convergent evolution, leading to many lineages of legless lizards. These resemble snakes, but several common groups of legless lizards have eyelids and external ears, which snakes lack, althoug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Squamata
Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest Order (biology), order of reptiles; most members of which are commonly known as Lizard, lizards, with the group also including Snake, snakes. With over 11,991 species, it is also the second-largest order of Neontology, extant (living) vertebrates, after the Perciformes, perciform fish. Squamates are distinguished by their skins, which bear horny scale (zoology), scales or shields, and must periodically engage in molting. They also possess movable quadrate bones, making possible movement of the Maxilla, upper jaw relative to the neurocranium. This is particularly visible in snakes, which are able to open their mouths very widely to accommodate comparatively large prey. Squamates are the most variably sized living reptiles, ranging from the Sphaerodactylus ariasae, dwarf gecko (''Sphaerodactylus ariasae'') to the reticulated python (''Malayopython reticulatus''). The now-Extinction, extinct mosasaurs reached ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rattlesnake Hemipene
Rattlesnakes are venomous snakes that form the genus, genera ''Crotalus'' and ''Sistrurus'' of the subfamily Crotalinae (the pit vipers). All rattlesnakes are vipers. Rattlesnakes are predators that live in a wide array of habitats, hunting small animals such as birds and rodents. Rattlesnakes receive their name from the #Rattle, rattle located at the end of their tails, which makes a loud rattling noise when tail vibration, vibrated that deters predators. Rattlesnakes are the leading contributor to snakebite injuries in North America, but rarely bite unless provoked or threatened; if treated promptly, the bites are seldom fatal. The 36 known List of rattlesnake species and subspecies, species of rattlesnakes have between 65 and 70 subspecies, all native to the Americas, ranging from central Argentina to southern Canada. The largest rattlesnake, the Eastern diamondback rattlesnake, eastern diamondback, can measure up to in length. Rattlesnakes are preyed upon by hawks, wease ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammalian Penis
A penis (; : penises or penes) is a sex organ through which male and hermaphrodite animals expel semen during copulation, and through which male placental mammals and marsupials also urinate. The term ''penis'' applies to many intromittent organs of vertebrates and invertebrates, but not to all. As an example, the intromittent organ of most Cephalopoda is the hectocotylus, a specialized arm, and male spiders use their pedipalps. Even within the Vertebrata, there are morphological variants with specific terminology, such as hemipenes. Etymology The word "penis" is taken from the Latin word for "tail". Some derive that from Indo-European ''*pesnis'', and the Greek word πέος = "penis" from Indo-European ''*pesos''. Prior to the adoption of the Latin word in English, the penis was referred to as a "yard". The Oxford English Dictionary cites an example of the word ''yard'' used in this sense from 1379, and notes that in his ''Physical Dictionary'' of 1684, Steven Blankaa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rattlesnake Hemipenes
Rattlesnakes are venomous snakes that form the genera ''Crotalus'' and ''Sistrurus'' of the subfamily Crotalinae (the pit vipers). All rattlesnakes are vipers. Rattlesnakes are predators that live in a wide array of habitats, hunting small animals such as birds and rodents. Rattlesnakes receive their name from the rattle located at the end of their tails, which makes a loud rattling noise when vibrated that deters predators. Rattlesnakes are the leading contributor to snakebite injuries in North America, but rarely bite unless provoked or threatened; if treated promptly, the bites are seldom fatal. The 36 known species of rattlesnakes have between 65 and 70 subspecies, all native to the Americas, ranging from central Argentina to southern Canada. The largest rattlesnake, the eastern diamondback, can measure up to in length. Rattlesnakes are preyed upon by hawks, weasels, kingsnakes, and a variety of other species. Rattlesnakes are heavily preyed upon as neonates, while t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Penis
In Human body, human anatomy, the penis (; : penises or penes; from the Latin ''pēnis'', initially 'tail') is an external sex organ (intromittent organ) through which males urination, urinate and ejaculation, ejaculate, as Penis, on other animals. Together with the testes and surrounding structures, the penis functions as part of the male reproductive system. The main parts of the penis are the Root of penis, root, Body of penis, body, the epithelium of the penis, including the shaft skin, and the foreskin covering the glans penis, glans. The body of the penis is made up of three columns of tissue (biology), tissue: two Corpus cavernosum penis, corpora cavernosa on the dorsal side and corpus spongiosum penis, corpus spongiosum between them on the ventral side. The Urethra#Male, urethra passes through the prostate gland, where it is joined by the ejaculatory ducts, and then through the penis. The urethra goes across the corpus spongiosum and ends at the tip of the glans as the o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boiga Multomaculata
''Boiga'' is a large genus of rear-fanged, mildly venomous snakes, known commonly as cat-eyed snakes or simply cat snakes, in the family Colubridae. Species of the genus ''Boiga'' are native to southeast Asia, India, and Australia, but due to their extremely hardy nature and adaptability, have spread to many other suitable habitats around the world. There are 38 recognized species in the genus. According to the study done by Jiří Smíd regarding Old World cat snakes, the ancestor of the cat snake originated in Africa, from where it diversified and expanded to other countries. Despite this diversity however, the different species have very similar needs in terms of temperature and precipitation. Species and subspecies The following species and subspecies are recognized as being valid. *'' Boiga andamanensis'' – Andaman cat snake *'' Boiga angulata'' – Leyte cat snake – Philippines *'' Boiga barnesii'' – Barnes' cat snake – Sri Lanka *'' Boiga beddomei'' – Bedd ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phymaturus
''Phymaturus'' is a genus of iguanian lizards of the Family (biology), family Liolaemidae, a family which was traditionally included in the Iguanidae as a subfamily, but more recently was proposed to warrant family status in the Liolaemidae. ''Phymaturus'' is the mid-sized genus of its family, with 50 species altogether known as of 2021; new species are still being discovered, however.Scolaro et al. (2008). Species of the genus ''Phymaturus'' are found in the Andes region south to Patagonia and inhabit a variety of habitats. Their habits are mostly conserved from the ancestral iguanians, in that ''Phymaturus'' are generally inhabitants of rocky ground, feed on plants, and give birth to fully developed young. Systematics The genus can be divided into two lineages, which probably represent clades: ''palluma'' group :Superciliar scales not imbricate, more than four subocular scales, 3-4 rows of lorilabial scales, mental scale narrower than rostral scale and usually touching the su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homology (biology)
In biology, homology is similarity in anatomical structures or genes between organisms of different taxa due to shared ancestry, ''regardless'' of current functional differences. Evolutionary biology explains homologous structures as retained heredity from a common descent, common ancestor after having been subjected to adaptation (biology), adaptive modifications for different purposes as the result of natural selection. The term was first applied to biology in a non-evolutionary context by the anatomist Richard Owen in 1843. Homology was later explained by Charles Darwin's theory of evolution in 1859, but had been observed before this from Aristotle's biology onwards, and it was explicitly analysed by Pierre Belon in 1555. A common example of homologous structures is the forelimbs of vertebrates, where the bat wing development, wings of bats and origin of avian flight, birds, the arms of primates, the front flipper (anatomy), flippers of whales, and the forelegs of quadrupedalis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
