|
Baculum
The baculum (: bacula), also known as the penis bone, penile bone, ''os penis'', ''os genitale'', or ''os priapi'', is a bone in the penis of many placental mammals. It is not present in humans, but is present in the penises of some primates, such as the gorilla and the chimpanzee. The baculum arises from primordial cells in soft tissues of the penis, and its formation is largely influenced by androgens. The bone lies above the male urethra, urethra, and it aids sexual reproduction by maintaining stiffness during sexual penetration. The Homology (biology), homologue to the baculum in female mammals is the baubellum (''os clitoridis''), a bone in the clitoris. Etymology The word ''baculum'' means "stick" or "staff" in Latin and originates from , ''baklon'' "stick". Function The baculum is used for copulation and varies in size and shape by species. Its evolution may be influenced by sexual selection, and its characteristics are sometimes used to differentiate between simila ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Os Clitoridis
The os clitoridis (also called the os clitoris, clitoral bone or baubellum; : baubella) is a bone inside the clitoris of many placental mammals. It is absent from the human clitoris, but present in clitoris#Non-human primates, the clitoris of some primates, such as ring-tailed lemurs and non-human great apes. However, in the latter case, the bone is greatly reduced in size. It is homologous to the baculum in male mammals. The structure is more evolutionarily labile than the baculum, exhibiting both more inherent variability and more gains and losses over time, which has been interpreted as evidence for its non-functionality. Other work posits that the variation in the os clitoridis could be driven by intersexual conflict, lock-and-key genital evolution, and cryptic female choice, especially given the high level of variation within species as well as between them. History The os clitoridis was described in 1666 by Claude Perrault in otters and in the lioness. The term ''os clit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Selection In Mammals
Sexual selection in mammals is a process the study of which started with Charles Darwin's observations concerning sexual selection, including sexual selection in humans, and in other mammals, consisting of male–male competition and mate choice that mold the development of future phenotypes in a population for a given species. Elephant seals A good example of intrasexual selection, in which males fight for dominance over a Harem (zoology), harem of females, is the elephant seal – large, oceangoing mammals of the genus ''Mirounga''. There are two species: the northern elephant seal, northern (''M. angustirostris'') and southern elephant seal (''M. leonina'') – the largest Carnivora, carnivoran living today. Both species show extreme sexual dimorphism, possibly the largest of any mammal, with southern males typically five to six times heavier than the females. While the females average and long, the bulls average and long. The record-sized bull, shot in Possession Bay, S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Copulation (zoology)
In zoology, copulation is animal sexual behavior in which a male introduces sperm into the female's body, especially directly into her reproductive tract. This is an aspect of mating. Many aquatic animals use external fertilization, whereas internal fertilization may have developed from a need to maintain gametes in a liquid medium in the Late Ordovician epoch. Internal fertilization with many vertebrates (such as all reptiles, some fish, and most birds) occurs via cloacal copulation, known as cloacal kiss (see also hemipenis), while most mammals copulate vaginally, and many basal vertebrates reproduce sexually with external fertilization. In spiders and insects Spiders are often confused with insects, but they are not insects; instead, they are arachnids. Spiders have separate male and female sexes. Before mating and copulation, the male spider spins a small web and ejaculates on to it. He then stores the sperm in reservoirs on his large pedipalps, from which he tran ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chimpanzee
The chimpanzee (; ''Pan troglodytes''), also simply known as the chimp, is a species of Hominidae, great ape native to the forests and savannahs of tropical Africa. It has four confirmed subspecies and a fifth proposed one. When its close relative the bonobo was more commonly known as the pygmy chimpanzee, this species was often called the common chimpanzee or the robust chimpanzee. The chimpanzee and the bonobo are the only species in the genus Pan (genus), ''Pan''. Evidence from fossils and DNA sequencing shows that ''Pan'' is a sister taxon to the Human evolution, human lineage and is thus humans' closest living relative. The chimpanzee is covered in coarse black hair but has a bare face, fingers, toes, palms of the hands, and soles of the feet. It is larger and more robust than the bonobo, weighing for males and for females and standing . The chimpanzee lives in groups that range in size from 15 to 150 members, although individuals travel and forage in much smaller grou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spider Monkey
Spider monkeys are New World monkeys belonging to the genus ''Ateles'', part of the subfamily Atelinae, family Atelidae. Like other atelines, they are found in tropical forests of Central and South America, from southern Mexico to Brazil. The genus consists of seven species, all of which are under threat; the brown spider monkey is critically endangered. They are also notable for their ability to be easily Monkey breeding, bred in captivity. Disproportionately long limbs and long prehensile tails make them one of the largest New World monkeys and give rise to their common name. Spider monkeys live in the upper layers of the rainforest and forage in the high canopy, from . They primarily eat fruits, but will also occasionally consume leaves, flowers, and insects. Due to their large size, spider monkeys require large tracts of moist evergreen forests, and prefer undisturbed primary rainforest. They are social animals and live in bands of up to 35 individuals, but will split up to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rodent
Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal species are rodents. They are native to all major land masses except for Antarctica, and several oceanic islands, though they have subsequently been introduced to most of these land masses by human activity. Rodents are extremely diverse in their ecology and lifestyles and can be found in almost every terrestrial habitat, including human-made environments. Species can be arboreal, fossorial (burrowing), saltatorial/ricochetal (leaping on their hind legs), or semiaquatic. However, all rodents share several morphological features, including having only a single upper and lower pair of ever-growing incisors. Well-known rodents include Mouse, mice, rats, squirrels, prairie dogs, porcupines, beavers, Cavia, guinea pigs, and hamsters. Once included wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penis
A penis (; : penises or penes) is a sex organ through which male and hermaphrodite animals expel semen during copulation (zoology), copulation, and through which male placental mammals and marsupials also Urination, 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 Hemipenis, hemipenes. Etymology The word "penis" is taken from the Latin word for "Latin profanity#Synonyms and metaphors, tail". Some derive that from Proto-Indo-European language, 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 w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primate
Primates is an order (biology), order of mammals, which is further divided into the Strepsirrhini, strepsirrhines, which include lemurs, galagos, and Lorisidae, lorisids; and the Haplorhini, haplorhines, which include Tarsiiformes, tarsiers and simians (monkeys and apes). Primates arose 74–63 million years ago first from small terrestrial animal, terrestrial mammals, which adapted for life in tropical forests: many primate characteristics represent adaptations to the challenging environment among Canopy (biology), tree tops, including large brain sizes, binocular vision, color vision, Animal communication, vocalizations, shoulder girdles allowing a large degree of movement in the upper limbs, and opposable thumbs (in most but not all) that enable better grasping and dexterity. Primates range in size from Madame Berthe's mouse lemur, which weighs , to the eastern gorilla, weighing over . There are 376–524 species of living primates, depending on which classification is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sexual Selection
Sexual selection is a mechanism of evolution in which members of one sex mate choice, choose mates of the other sex to mating, mate with (intersexual selection), and compete with members of the same sex for access to members of the opposite sex (intrasexual selection). These two forms of selection mean that some individuals have greater reproductive success than others within a population, for example because they are more Animal sexual behaviour, attractive or prefer more attractive partners to produce offspring. Successful males benefit from frequent mating and monopolizing access to one or more fertile females. Females can maximise the return on the energy they invest in reproduction by selecting and mating with the best males. The concept was first articulated by Charles Darwin who wrote of a "second agency" other than natural selection, in which competition between mate candidates could lead to speciation. The theory was given a mathematical basis by Ronald Fisher in the e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Woolly Monkey
The woolly monkeys are the genus ''Lagothrix'' of New World monkeys, usually placed in the family Atelidae. Both species in this genus originate from the rainforests of South America. They have prehensile tails and live in relatively large social groups. Taxonomy The following 2 species and 5 subspecies are currently considered to be within the genus: Description Woolly monkeys are closely related to spider monkeys. They have a thick brown coat with dark gray appendages. The stomach area is black and heads are light brown. The fur color is the same for both males and females. Variation in color exist among subspecies. A prehensile tail assists in climbing and fulfills many functions of an opposable thumb. Arm and legs are about equal in length. All species are large, weighing around . Males weigh 45% more than females on average but are of equal length. Habitat and social behaviour Woolly monkeys are found throughout the northern countries of South America (Bolivia, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genes & Development
''Genes & Development'' is a peer-reviewed scientific journal covering molecular biology, molecular genetics, cell biology, and development. It was established in 1987 and is published twice monthly by Cold Spring Harbor Laboratory Press in association with The Genetics Society. According to the ''Journal Citation Reports'', the journal has a 2012 impact factor of 12.44, ranking it 14th out of 181 journals in the category "Cell Biology", third out of 40 journals in the category "Developmental Biology", and 7th out of 158 journals in the category "Genetics & Heredity". Over 1999–2004, the journal was ranked fifth in the "Molecular Biology and Genetics" category according to ''ScienceWatch'', with an average of 47 citations per paper. All issues are available online via the journal website as PDFs, with a text version additionally available from August 1997. Content over 6 months old is freely available. Since 1989, the editor-in-chief has been Terri Grodzicker (Cold Spring Harbo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Loris
Loris is the common name for the strepsirrhine mammals of the subfamily Lorinae (sometimes spelled Lorisinae) in the family Lorisidae. ''Loris'' is one genus in this subfamily and includes the slender lorises, ''Nycticebus'' is the genus containing the slow lorises, and ''Xanthonycticebus'' is the genus name of the pygmy slow loris. Description Lorises are nocturnal and arboreal. They are found in tropical and woodland forests of India, Sri Lanka, and parts of southeast Asia. Their locomotion is a slow and cautious climbing form of quadrupedalism. Some lorises are almost entirely insectivorous, while others also include fruits, gums, leaves, and slugs in their diet. Lorises, like most strepsirrhines, have a special adaptation called a " toothcomb" in their lower front teeth, which they use for grooming their fur and even injecting their venom. Female lorises practice ''infant parking'', leaving their infants behind in trees or bushes. Before they do this, they bathe the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
