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A penis (plural ''penises'' or ''penes'' () is the primary
sexual organ A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female, a ...
that
male Male (Mars symbol, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot sexual reproduction, repro ...
animals use to
inseminate Insemination is the introduction of spermatozoon, sperm into a female’s reproductive system for the purpose of impregnating, also called Fertilization, fertilizing, the female for sexual reproduction. The sperm is introduced into the uterus of a ...
females (or
hermaphrodite In reproductive biology, a hermaphrodite () is an organism that has both kinds of reproductive organs and can produce both gametes associated with male and female sexes. Many Taxonomy (biology), taxonomic groups of animals (mostly invertebrate ...
s) during
copulation Sexual intercourse (or coitus or copulation) is a sexual activity typically involving the insertion and Pelvic thrust, thrusting of the penis into the vagina for Sexual stimulation, sexual pleasure or sexual reproduction, reproduction.Sexual i ...
. Such organs occur in many animals, both
vertebrate Vertebrates () comprise all animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually ...
and
invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordata, ...
, but males do not bear a penis in every animal species, and in those species in which the male does bear a so-called penis, the penises in the various species are not necessarily homologous. The term ''penis'' applies to many
intromittent organ An intromittent organ is any external organ of a male organism that is specialized to deliver sperm during Copulation (zoology), copulation. Intromittent organs are found most often in terrestrial species, as most non-mammalian aquatic species f ...
s, but not to all. As an example, the intromittent organ of most
cephalopod A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...
a is the
hectocotylus A hectocotylus (plural: ''hectocotyli'') is one of the cephalopod limb, arms of male cephalopods that is specialized to store and transfer spermatophores to the female. Structurally, hectocotyli are muscular hydrostats. Depending on the species, t ...
, a specialized arm, and male spiders use their
pedipalp Pedipalps (commonly shortened to palps or palpi) are the second pair of appendages of Chelicerata, chelicerates – a group of arthropods including spiders, scorpions, horseshoe crabs, and sea spiders. The pedipalps are lateral to the chelicerae ...
s. Even within the
Vertebrata Vertebrates () comprise all animal taxon, taxa within the subphylum Vertebrata () (chordates with vertebral column, backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the ...
there are morphological variants with specific terminology, such as hemipenes. In most species of animals in which there is an organ that might reasonably be described as a penis, it has no major function other than intromission, or at least conveying the sperm to the female, but in the
placental mammals Placental mammals ( infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupial Marsupials are any members of the mammalian infraclass Marsupialia. All extant mars ...
the penis bears the
distal Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...
part of the
urethra The urethra (from Greek language, Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, ...
, which discharges both
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra. Cel ...
during
urination Urination, also known as micturition, is the release of urine from the urinary bladder through the urethra to the outside of the body. It is the urinary system's form of excretion. It is also known medically as micturition, voiding, uresis, ...
and
semen Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoon, spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphrodite, hermaphroditic animals and can fertili ...
during copulation.


Vertebrates


Birds

Most male birds (e.g.,
rooster The chicken (''Gallus gallus domesticus'') is a domestication, domesticated junglefowl species, with attributes of wild species such as the grey junglefowl, grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster ...
s and
turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with a East Thrace, small portion on th ...
s) have a
cloaca In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and bir ...
(also present on the female), but not a penis. Among bird species with a penis are
paleognathes Palaeognathae (; ) is a infraclass of birds, called paleognaths, within the Class (biology), class Aves of the clade Archosauria. It is one of the two extant taxon, extant infraclasses of birds, the other being Neognathae, both of which form Neo ...
(
tinamou Tinamous () form an order (biology), order of birds called Tinamiformes (), comprising a single family (biology), family called Tinamidae (), divided into two distinct subfamily, subfamilies, containing 46 species found in Mexico, Central America ...
s and
ratites A ratite () is any of a diverse group of flightless bird, flightless, large, long-necked, and long-legged birds of the infraclass Palaeognathae. Kiwi (bird), Kiwi, the exception, are much smaller and shorter-legged and are the only nocturnal exta ...
) and
Anatidae The Anatidae are the biological family (biology), family of water birds that includes ducks, goose, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted ...
(ducks, geese and swans). A bird penis is different in structure from
mammal penis A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during Copulation (zoology), copulation. Such organs occur in many animals, both #Vertebrates, vertebra ...
es, being an erectile expansion of the cloacal wall and being erected by
lymph Lymph (from Latin, , meaning "water") is the fluid that flows through the lymphatic system, a system composed of lymph vessels (channels) and intervening lymph nodes whose function, like the venous system, is to return fluid from the tissues to ...
, not blood. It is usually partially feathered and in some species features spines and brush-like filaments, and in flaccid state curls up inside the
cloaca In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and bir ...
. While most male birds have no external genitalia, male waterfowl (
Anatidae The Anatidae are the biological family (biology), family of water birds that includes ducks, goose, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted ...
) have a phallus. Most birds mate with the males balancing on top of the females and touching cloacas in a "cloacal kiss"; this makes forceful insemination very difficult. The phallus that male waterfowl have evolved everts out of their bodies (in a clockwise coil) and aids in inseminating females without their cooperation.Brennan, P. L. R. et al. Coevolution of male and female genital morphology in waterfowl. ''PLoS ONE'' 2, e418 (2007). The male waterfowl evolution of a phallus to forcefully copulate with females has led to counteradaptations in females in the form of vaginal structures called dead end sacs and clockwise coils. These structures make it harder for males to achieve intromission. The clockwise coils are significant because the male phallus everts out of their body in a counter-clockwise spiral; therefore, a clockwise vaginal structure would impede forceful copulation. Studies have shown that the longer a male's phallus is, the more elaborate the vaginal structures were. The lake duck is notable for possessing, in relation to body length, the longest penis of all
vertebrates Vertebrates () comprise all animal taxon, taxa within the subphylum Vertebrata () (chordates with vertebral column, backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the ...
; the penis, which is typically coiled up in flaccid state, can reach about the same length as the animal himself when fully erect, but is more commonly about half the bird's length. It is theorized that the remarkable size of their spiny penises with bristled tips may have evolved in response to competitive pressure in these highly promiscuous birds, removing sperm from previous matings in the manner of a bottle brush. The lake duck has a corkscrew shaped penis. Male and female
emu The emu () (''Dromaius novaehollandiae'') is the second-tallest living bird after its ratite A ratite () is any of a diverse group of flightless bird, flightless, large, long-necked, and long-legged birds of the infraclass Palaeognathae. ...
s are similar in appearance,Eastman, p. 23. although the male's penis can become visible when it defecates.Coddington and Cockburn, p. 366. The male tinamou has a corkscrew shaped penis, similar to those of the ratites and to the
hemipenis A hemipenis (plural hemipenes) is one of a pair of intromittent organs of male squamata, squamates (snakes, lizards and amphisbaenia, worm lizards). Hemipenes are usually held inverted within the body, and are everted for reproduction via erecti ...
of some reptiles. Females have a small phallic organ in the cloaca which becomes larger during the breeding season.


Mammals

As with any other bodily attribute, the length and girth of the penis can be highly variable between mammals of different
species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
. In many mammals, the size of a flaccid penis is smaller than its erect size. A bone called the
baculum The baculum (also penis bone, penile bone, or ''os penis'', ''os genitale'' or ''os priapi'') is a bone found in the penis of many placental mammals. It is absent from the human penis, but present in Penis#Primates, the penises of some primate ...
or ''os penis'' is present in most mammals but absent in humans, cattle and
horse The horse (''Equus ferus caballus'') is a Domestication, domesticated, odd-toed ungulate, one-toed, ungulate, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two Extant taxon, extant subspecies of wild horse, ''Equus fer ...
s. In mammals the penis is divided into three parts: * Roots ( crura): these begin at the
caudal Caudal may refer to: Anatomy * Caudal (anatomical term) Standard anatomical terms of location are used to unambiguously describe the anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and ...
border of the pelvic ischial arch. * Body: the part of the penis extending from the roots. *
Glans The glans (, plural "glandes" ; from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then k ...
: the free end of the penis. The internal structures of the penis consist mainly of cavernous,
erectile tissue Erectile tissue is tissue in the body with numerous vascular spaces, or cavernous tissue, that may become engorged with blood. However, tissue that is devoid of or otherwise lacking erectile tissue (such as the labia minora, the vestibule/vagina and ...
, which is a collection of blood sinusoids separated by sheets of
connective tissue Connective tissue is one of the four primary types of animal tissue (biology), tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Con ...
(trabeculae). Some mammals have a lot of erectile tissue relative to connective tissue, for example horses. Because of this a horse's penis can enlarge more than a bull's penis. The
urethra The urethra (from Greek language, Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, ...
is on the ventral side of the body of the penis. As a general rule, a mammal's penis is proportional to its body size, but this varies greatly between specieseven between closely related ones. For example, an adult
gorilla Gorillas are herbivorous, predominantly ground-dwelling great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four or fi ...
's erect penis is about in length; an adult
chimpanzee The chimpanzee (''Pan troglodytes''), also known as simply the chimp, is a species of great ape native to the forest and savannah of tropical Africa Although tropical Africa is mostly familiar to the Western world, West for its rainfore ...
, significantly smaller (in body size) than a gorilla, has a penis size about double that of the gorilla. In comparison, the
human penis The human penis is an external male intromittent organ that additionally serves as the urination, urinary duct. The main parts are the root (radix); the body (corpus); and the epithelium of the penis including the shaft skin and the foreskin (p ...
is larger than that of any other
primate Primates are a diverse order (biology), order of mammals. They are divided into the Strepsirrhini, strepsirrhines, which include the lemurs, galagos, and lorisids, and the Haplorhini, haplorhines, which include the Tarsiiformes, tarsiers and ...
, both in proportion to body size and in absolute terms.


Artiodactyls

The penises of even-toed ungulates are curved in an S-shape when not erect. In
bull A bull is an intact (i.e., not Neutering, castrated) adult male of the species ''Cattle, Bos taurus'' (cattle). More muscular and aggressive than the females of the same species (i.e., Cattle, cows), bulls have long been an important symbol i ...
s,
rams In engineering Engineering is the use of scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and buildings. The discipline of engineering encompasses a broad range ...
and
boar The wild boar (''Sus scrofa''), also known as the wild swine, common wild pig, Eurasian wild pig, or simply wild pig, is a Suidae, suid native to much of Eurasia and North Africa, and has been introduced to the Americas and Oceania. The speci ...
s, the sigmoid flexure of the penis straightens out during erection. When mating, the tip of a male
pronghorn The pronghorn (, ) (''Antilocapra americana'') is a species of Even-toed ungulate, artiodactyl (even-toed, hoofed) mammal indigenous to interior western and central North America. Though not an antelope, it is known colloquially in North America ...
's penis is often the first part to touch the female pronghorn. The pronghorn's penis is about long, and is shaped like an ice pick. The front of a pronghorn's glans penis is relatively flat, while the back is relatively thick. The male pronghorn usually ejaculates immediately after intromission. The penis of a
dromedary The dromedary (''Camelus dromedarius'' or ;), also known as the dromedary camel, Arabian camel, or one-humped camel, is a large even-toed ungulate, of the genus ''Camelus'', with one hump on its back. It is the tallest of the three species of ...
camel is covered by a triangular penile sheath opening backwards, and is about long. The camelmen often aid the male to enter his penis into the female's
vulva The vulva (plural: vulvas or vulvae; derived from Latin for wrapper or covering) consists of the external sex organ, female sex organs. The vulva includes the mons pubis (or mons veneris), labia majora, labia minora, clitoris, bulb of vestibu ...
, though the male is considered able to do it on his own. Copulation time ranges from 7 to 35 minutes, averaging 11–15 minutes. Bulls have a fibro-elastic penis. Given the small amount of erectile tissue, there is little enlargement after erection. The penis is quite rigid when non-erect, and becomes even more rigid during erection. Protrusion is not affected much by erection, but more by relaxation of the
retractor penis muscle In some animals the male penis possesses a muscle enabling Anatomical terms of motion, retraction into the penile sheath, prepuce. In particular animals The retractor penis muscle occurs in marsupials and carnivorans, but it is absent in humans. ...
and straightening of the sigmoid flexure. The male genitalia of
mouse deer Chevrotains, or mouse-deer, are small even-toed ungulates that make up the family (biology), family Tragulidae, the only extant members of the infraorder Tragulina. The 10 Extant taxon, extant species are placed in three genera, but sever ...
are similar to those of pigs. A boar's penis, which rotates rhythmically during copulation, is about long, and ejaculates about a pint of semen. Wild boars have a roughly egg-sized sack near the opening of the penis, which collects urine and emits a sharp odour. The purpose of this is not fully understood.Heptner, V. G.; Nasimovich, A. A.; Bannikov, A. G.; Hoffman, R. S. (1988
''Mammals of the Soviet Union''
Volume I, Washington, D.C. : Smithsonian Institution Libraries and National Science Foundation, pp. 19-82


=Deer

= A stag's penis forms an S-shaped curve when it is not erect, and is retracted into its sheath by the retractor penis muscle. Some deer species spray urine on their bodies by urinating from an erect penis. One type of scent-marking behavior in elk is known as "thrash-urination, which typically involves palpitation of the erect penis. A male elk's urethra points upward so that urine is sprayed almost at a right angle to the penis. A sambar stag will mark himself by spraying urine directly in the face with a highly mobile penis, which is often erect during its rutting activities.''Deer of the world: their evolution, behaviour, and ecology.'' Valerius Geist. Stackpole Books. 1998. Pg. 73-77.
Red deer The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or hart, and a female is called a hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Iran, and parts of wes ...
stags often have erect penises during combat.


Cetaceans

Cetaceans' reproductive organs are located inside the body. Male
cetaceans Cetacea (; , ) is an infraorder of aquatic mammals that includes whales, dolphins, and porpoises. Key characteristics are their fully aquatic lifestyle, streamlined body shape, often large size and exclusively carnivorous diet. They propel thems ...
(whales, dolphins, and porpoises) have two slits, the genital groove concealing the penis and one further behind for the
anus The anus (Latin, 'ring' or 'circle') is an opening at the opposite end of an animal's digestive tract from the mouth. Its function is to control the expulsion of feces, the residual semi-solid waste that remains after food digestion, which, de ...
. Cetaceans have fibroelastic penises, similar to those of
Artiodactyla The even-toed ungulates (Artiodactyla , ) are ungulates—hoofed animals—which bear weight equally on two (an even number) of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing poster ...
. The tapering tip of the cetacean penis is called the ''pars intrapraeputialis'' or ''terminal cone''. The
blue whale The blue whale (''Balaenoptera musculus'') is a marine mammal and a baleen whale. Reaching a maximum confirmed length of and weighing up to , it is the largest animal known to have ever existed. The blue whale's long and slender body can b ...
has the largest penis of any organism on the planet, typically measuring . Accurate measurements are difficult to take because its erect length can only be observed during mating, which occurs underwater. The penis on a
right whale Right whales are three species of large baleen whales of the genus ''Eubalaena'': the North Atlantic right whale (''E. glacialis''), the North Pacific right whale (''E. japonica'') and the Southern right whale (''E. australis''). They are class ...
can be up to – the
testes A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is Homology (biology), homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, pr ...
, at up to in length, in diameter, and weighing up to , are also by far the largest of any animal on Earth. On at least one occasion, a dolphin towed bathers through the water by hooking his erect penis around them. Between male bottlenose dolphins, homosexual behaviour includes rubbing of genitals against each other, which sometimes leads to the males swimming belly to belly, inserting the penis in the other's genital slit and sometimes anus.


Perissodactyls

Stallion A stallion is a male horse that has not been Gelding, gelded (castrated). Stallions follow the horse conformation, conformation and phenotype of their list of horse breeds, breed, but within that standard, the presence of hormones such as testos ...
s (male horses) have a vascular penis. When non-erect, it is quite flaccid and contained within the prepuce (foreskin, or sheath).
Tapirs Tapirs ( ) are large, herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbiv ...
have exceptionally long penises relative to their body size. The glans of the Malayan tapir resembles a mushroom, and is similar to the glans of the horse. The penis of the
Sumatran rhinoceros The Sumatran rhinoceros (''Dicerorhinus sumatrensis''), also known as the Sumatran rhino, hairy rhinoceros or Asian two-horned rhinoceros, is a rare member of the family Rhinocerotidae and one of five extant species of rhinoceros. It is the o ...
contains two lateral lobes and a structure called the ''processus glandis''.


Carnivores

All members of
Carnivora Carnivora is a monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population Populatio ...
(except
hyenas Hyenas, or hyaenas (from Ancient Greek , ), are feliformia, feliform carnivoran mammals of the family Hyaenidae . With only four extant species (each in its own genus), it is the fifth-smallest family (taxonomy), family in the Carnivora and ...
) have a baculum. Canine penises have a structure at the base called the
bulbus glandis The bulbus glandis (also called a bulb or knot) is an erectile tissue structure on the penis of canid mammals. During mating, immediately before ejaculation the tissues swell up to lock ('' tie'') the male's penis inside the female. The locking ...
. During copulation, the spotted hyena inserts his penis through the female's pseudo-penis instead of directly through the
vagina In mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region o ...
, which is blocked by the false scrotum and testes. Once the female retracts her clitoris, the male enters the female by sliding beneath her, an operation facilitated by the penis's upward angle. The pseudo-penis closely resembles the male hyena's penis, but can be distinguished from the male's genitalia by its greater thickness and more rounded
glans The glans (, plural "glandes" ; from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then k ...
. In male spotted hyenas, as well as females, the base of the glans is covered with penile spines.
Domestic cats The cat (''Felis catus'') is a domestic species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the l ...
have barbed penises, with about 120–150 one millimeter long backwards-pointing spines. Upon withdrawal of the penis, the spines rake the walls of the female's vagina, which is a trigger for
ovulation Ovulation is the release of egg cells, eggs from the ovaries. In women, this event occurs when the ovarian follicles rupture and release the secondary oocyte ovarian cells. After ovulation, during the luteal phase, the egg will be available to be ...
. Lions also have barbed penises. Male felids urinate backwards by curving the tip of the
glans penis In male Male (Mars symbol, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot sexual repr ...
backward. When male cheetahs urine-mark their territories, they stand one meter away from a tree or rock surface with the tail raised, pointing the penis either horizontally backward or 60° upward. The male fossa has an unusually long penis and
baculum The baculum (also penis bone, penile bone, or ''os penis'', ''os genitale'' or ''os priapi'') is a bone found in the penis of many placental mammals. It is absent from the human penis, but present in Penis#Primates, the penises of some primate ...
(penis bone), reaching to between his front legs when erect with backwards-pointing spines along most of its length. The male fossa has scent glands near the penis, with the penile glands emitting a strong odor. The beech marten's penis is larger than the pine marten's, with the bacula of young beech martens often outsizing those of old pine martens.
Raccoon The raccoon ( or , ''Procyon lotor''), sometimes called the common raccoon to distinguish it from other species, is a mammal native to North America. It is the largest of the procyonid family, having a body length of , and a body weight of . ...
s have penis bones which bend at a 90 degree angle at the tip. The extrusibility of a raccoon's penis can be used to distinguish mature males from immature males. Male
walrus The walrus (''Odobenus rosmarus'') is a large pinniped, flippered marine mammal with a discontinuous distribution about the North Pole in the Arctic Ocean and subarctic seas of the Northern Hemisphere. The walrus is the only living species in ...
es possess the largest penis bones of any land mammal, both in absolute size and relative to body size. The adult male
American mink The American mink (''Neogale vison'') is a semiaquatic species of Mustelidae, mustelid native to North America, though human intervention has expanded its range to many parts of Europe, Asia and South America. Because of range expansion, the Ame ...
's penis is long, and is covered by a sheath. The
baculum The baculum (also penis bone, penile bone, or ''os penis'', ''os genitale'' or ''os priapi'') is a bone found in the penis of many placental mammals. It is absent from the human penis, but present in Penis#Primates, the penises of some primate ...
is well-developed, being triangular in
cross section Cross section may refer to: * Cross section (geometry) **Multiview orthographic projection#Section, Cross-sectional views in architecture & engineering 3D *Cross section (geology) * Cross section (electronics) * Radar cross section, measure of det ...
and curved at the tip.


Bats

Males of Racey's pipistrelle bat have a long, straight penis with a notch between the shaft and the narrow, egg-shaped
glans penis In male Male (Mars symbol, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot sexual repr ...
. Near the top, the penis is haired, but the base is almost naked. In the
baculum The baculum (also penis bone, penile bone, or ''os penis'', ''os genitale'' or ''os priapi'') is a bone found in the penis of many placental mammals. It is absent from the human penis, but present in Penis#Primates, the penises of some primate ...
(penis bone), the shaft is long and narrow and slightly curved. The length of the penis and baculum distinguish ''P. raceyi'' from all comparably sized African and Malagasy vespertilionids. In males, penis length is and baculum length is . Copulation by male
greater short-nosed fruit bat The greater short-nosed fruit bat (''Cynopterus sphinx''), or short-nosed Indian fruit bat, is a species of megabat in the family Pteropodidae found in South and Southeast Asia. Description These bats have a relatively long snout. Their upper pa ...
s is dorsoventral and the females lick the shaft or the base of the male's penis, but not the glans which has already penetrated the vagina. While the females do this, the penis is not withdrawn and research has shown a positive relationship between length of the time that the penis is licked and the duration of copulation. Post copulation genital grooming has also been observed.


Rodents

The glans penis of the marsh rice rat is long and robust, averaging long and broad, and the baculum (penis bone) is long. As is characteristic of
Sigmodontinae The rodent subfamily Sigmodontinae includes New World rats and Mouse, mice, with at least 376 species. Many authorities include the Neotominae and Tylomyinae as part of a larger definition of Sigmodontinae. When those genera are included, the sp ...
, the marsh rice rat has a complex penis, with the distal (far) end of the baculum ending in three digits. The central digit is notably larger than those at the sides. The outer surface of the penis is mostly covered by small spines, but there is a broad band of nonspinous tissue. The papilla (nipple-like projection) on the dorsal (upper) side of the penis is covered with small spines, a character the marsh rice rat shares only with ''
Oligoryzomys ''Oligoryzomys'' is a genus of rodents in the tribe Oryzomyini of family Cricetidae. Many species are known as pygmy rice rats or colilargos.Musser and Carleton, 2005 The genus is found from Mexico to Tierra del Fuego and includes approximately 1 ...
'' and ''Oryzomys couesi'' among oryzomyines examined. On the urethral process, located in the crater at the end of the penis, a fleshy process (the subapical lobule) is present; it is absent in all other oryzomyines with studied penes except ''O. couesi'' and '' Holochilus brasiliensis''. The baculum is deeper than it is wide. In '' Transandinomys talamancae'', the outer surface of the penis is mostly covered by small spines, but there is a broad band of nonspinous tissue. Some features of the accessory glands in the male genital region vary among oryzomyines. In ''Transandinomys talamancae'', a single pair of preputial glands is present at the penis. As is usual for sigmodontines, there are two pairs of
ventral Standard anatomical terms of location are used to unambiguously describe the anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that ...
prostate The prostate is both an Male accessory gland, accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, ...
glands and a single pair of
anterior Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Itali ...
and dorsal prostate glands. Part of the end of the vesicular gland is irregularly folded, not smooth as in most oryzomyines. In Pseudoryzomys, the
baculum The baculum (also penis bone, penile bone, or ''os penis'', ''os genitale'' or ''os priapi'') is a bone found in the penis of many placental mammals. It is absent from the human penis, but present in Penis#Primates, the penises of some primate ...
(penis bone) displays large protuberances at the sides. In the
cartilaginous Cartilage is a resilient and smooth type of connective tissue Connective tissue is one of the four primary types of animal tissue (biology), tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchym ...
part of the baculum, the central digit is smaller than those at the sides. In Drymoreomys, there are three digits at the tip of the penis, of which the central one is the largest. In '' Thomasomys ucucha'' the
glans penis In male Male (Mars symbol, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot sexual repr ...
is rounded, short, and small and is superficially divided into left and right halves by a trough at the top and a ridge at the bottom. The
glans penis In male Male (Mars symbol, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot sexual repr ...
of a male
cape ground squirrel The Cape ground squirrel or South African ground squirrel (''Geosciurus inauris'') is found in most of the drier parts of southern Africa from South Africa, through to Botswana, and into Namibia, including Etosha National Park. The name ''Cap ...
is large with a prominent baculum. Unlike other squirrel species,
red squirrel The red squirrel (''Sciurus vulgaris'') is a species of tree squirrel in the genus ''Sciurus'' common throughout Eurasia, Europe and Asia. The red squirrel is an arboreal, primarily herbivorous rodent. In Great Britain, Ireland, and in Italy ...
s have long, thin, and narrow penises, without a prominent baculum. Winkelmann's mouse can easily be distinguished from its close relatives by the shape of its penis, which has a partially corrugated
glans The glans (, plural "glandes" ; from the Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then k ...
. The foreskin of a
capybara The capybaraAlso called capivara (in Brazil), capiguara (in Bolivia), chigüire, chigüiro, or fercho (in Colombia and Venezuela), carpincho (in Argentina, Paraguay and Uruguay) and ronsoco (in Peru). or greater capybara (''Hydrochoerus hydro ...
is attached to the anus in an unusual way, forming an anogenital invagination.


Primates

It has been postulated that the shape of the human penis may have been selected by
sperm competition Sperm competition is the competitive process between Spermatozoon, spermatozoa of two or more different males to fertility, fertilize the same egg during sexual reproduction. Competition can occur when females have multiple potential mating part ...
. The shape could have favored displacement of seminal fluids implanted within the female reproductive tract by rival males: the thrusting action which occurs during sexual intercourse can mechanically remove seminal fluid out of the
cervix The cervix or cervix uteri (Latin, 'neck of the uterus') is the lower part of the uterus (womb) in the human female reproductive system. The cervix is usually 2 to 3 cm long (~1 inch) and roughly cylindrical in shape, which changes during ...
area from a previous mating. The penile morphology of some types of
strepsirrhine Strepsirrhini or Strepsirhini (; ) is a suborder Order ( la, wikt:ordo#Latin, ordo) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between Family_(biology), family and Class_(biology), class. ...
primate Primates are a diverse order (biology), order of mammals. They are divided into the Strepsirrhini, strepsirrhines, which include the lemurs, galagos, and lorisids, and the Haplorhini, haplorhines, which include the Tarsiiformes, tarsiers and ...
s has provided information about their taxonomy. Male
galago Galagos , also known as bush babies, or ''nagapies'' (meaning "night monkeys" in Afrikaans), are small Nocturnality, nocturnal primates native to continental, sub-Sahara Africa, and make up the family (biology), family Galagidae (also sometime ...
species possess very distinctive penile morphology that can be used to classify species. The northern greater galago penis is on average in length, with doubled headed or even tridentate spines pointing towards the body. They are less densely packed than in ''Otolemur crassicaudatus''. The penis of the
ring-tailed lemur The ring-tailed lemur (''Lemur catta'') is a large Strepsirrhini, strepsirrhine primate and the most recognized lemur due to its long, black and white ringed tail. It belongs to Lemuridae, one of five lemur families, and is the only member of t ...
is nearly cylindrical in shape and is covered in small spines, as well as having two pairs of larger spines on both sides. The adult male of each
vervet monkey The vervet monkey (''Chlorocebus pygerythrus''), or simply vervet, is an Old World monkey of the family Cercopithecidae native to Africa Africa is the world's second-largest and second-most populous continent, after Asia in both case ...
species has a pale blue
scrotum The scrotum or scrotal sac is an Anatomy, anatomical male reproductive structure located at the base of the penis that consists of a suspended dual-chambered sac of skin and smooth muscle. It is present in most terrestrial male mammals. The scr ...
and a red penis, and male
proboscis monkey The proboscis monkey (''Nasalis larvatus'') or long-nosed monkey is an arboreal Old World monkey with an unusually large nose, a reddish-brown skin color and a long tail. It is Endemism, endemic to the southeast Asian island of Borneo and is fou ...
s have a red penis with a black scrotum. Male
baboons Baboons are primates comprising the biology, genus ''Papio'', one of the 23 genera of Old World monkeys. There are six species of baboon: the hamadryas baboon, the Guinea baboon, the olive baboon, the yellow baboon, the Kinda baboon and the ...
and
squirrel monkeys Squirrel monkeys are New World monkeys of the genus ''Saimiri''. ''Saimiri'' is the only genus in the subfamily Saimirinae. The name of the genus is of Tupi origin (''sai-mirím'' or ''çai-mbirín'', with ''sai'' meaning 'monkey' and ''mirím' ...
sometimes gesture with an erect penis as both a warning of impending danger and a threat to predators. In male
squirrel monkey Squirrel monkeys are New World monkeys of the genus ''Saimiri''. ''Saimiri'' is the only genus in the subfamily Saimirinae. The name of the genus is of tupi languages, Tupi origin (''sai-mirím'' or ''çai-mbirín'', with ''sai'' meaning 'monkey' ...
s, this gesture is used for social communication.


=Humans

= The human penis is an external sex organ of
male Male (Mars symbol, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot sexual reproduction, repro ...
human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedality, bipedalism and exceptional cognitive skills due to a large and complex Human brain, brain. This has enabled the development of ad ...
s. It is a
reproductive The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical sex organs, organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pherom ...
,
intromittent organ An intromittent organ is any external organ of a male organism that is specialized to deliver sperm during Copulation (zoology), copulation. Intromittent organs are found most often in terrestrial species, as most non-mammalian aquatic species f ...
that additionally serves as the urinal duct. The main parts are the root of the penis (radix): It is the attached part, consisting of the bulb of penis in the middle and the crus of penis, one on either side of the bulb; the body of the penis (corpus); and the
epithelium Epithelium or epithelial tissue is one of the four basic types of animal Tissue (biology), tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed Cell (biology), ...
of the penis consists of the shaft
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...
, the
foreskin In male Human body, human anatomy, the foreskin, also known as the prepuce, is the double-layered fold of skin, Mucous membrane, mucosal and Muscle tissue, muscular tissue at the distal end of the human penis that covers the glans penis, glans a ...
, and the
preputial mucosa The preputial mucosa of the penis is the epithelium of the inside of the prepuce, or foreskin. To differentiate it from the cutaneous skin of the outside of the Foreskin, prepuce, it is sometimes referred to as the inner mucosa. It starts at the ri ...
on the inside of the foreskin and covering the
glans penis In male Male (Mars symbol, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male organism cannot sexual repr ...
. The human penis is made up of three columns of tissue: two corpora cavernosa lie next to each other on the
dorsal side Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...
and one corpus spongiosum lies between them on the ventral side. The
urethra The urethra (from Greek language, Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, ...
, which is the last part of the
urinary tract The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, urinary bladder, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and bl ...
, traverses the corpus spongiosum, and its opening, known as the
meatus In anatomy, a meatus (, ),''OED'' 2nd edition, 1989, as . plural "meatus" or "meatuses",
, lies on the tip of the glans penis. It is a passage both for
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra. Cel ...
and for the
ejaculation Ejaculation is the discharge of semen (the ''ejaculate''; normally containing sperm) from the Male reproductive system, male reproductory tract as a result of an orgasm. It is the final stage and natural objective of male sexual stimulation, a ...
of
semen Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoon, spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphrodite, hermaphroditic animals and can fertili ...
. In males, the expulsion of
urine Urine is a liquid by-product of metabolism in humans and in many other animals. Urine flows from the kidneys through the ureters to the urinary bladder. Urination results in urine being excretion, excreted from the body through the urethra. Cel ...
from the body is done through the penis. The
urethra The urethra (from Greek language, Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, ...
drains the bladder through the
prostate gland The prostate is both an Male accessory gland, accessory gland of the male reproductive system and a muscle-driven mechanical switch between urination and ejaculation. It is found only in some mammals. It differs between species anatomically, ...
where it is joined by the
ejaculatory duct The ejaculatory ducts (''ductus ejaculatorii'') are paired structures in male anatomy. Each ejaculatory duct is formed by the union of the vas deferens with the Excretory duct of seminal gland, duct of the seminal vesicle. They pass through the pr ...
, and then onward to the penis. An erection is the stiffening and rising of the penis, which occurs during
sexual arousal Sexual arousal (also known as sexual excitement) describes the Physiology, physiological and psychological responses in preparation for sexual intercourse or when exposed to Sexual stimulation, sexual stimuli. A number of physiological respons ...
, though it can also happen in non-sexual situations. Ejaculation is the ejecting of
semen Semen, also known as seminal fluid, is an organic bodily fluid created to contain spermatozoon, spermatozoa. It is secreted by the gonads (sexual glands) and other sexual organs of male or hermaphrodite, hermaphroditic animals and can fertili ...
from the penis and is usually accompanied by
orgasm Orgasm (from Greek language, Greek , ; "excitement, swelling") or sexual climax is the sudden discharge of accumulated sexual excitement during the Human sexual response cycle, sexual response cycle, resulting in rhythmic, involuntary Muscle ...
. A series of muscular contractions delivers semen, containing male
gametes A gamete (; , ultimately ) is a Ploidy#Haploid and monoploid, haploid cell that fuses with another haploid cell during fertilization in organisms that Sexual reproduction, reproduce sexually. Gametes are an organism's reproductive cells, also r ...
known as sperm cells or
spermatozoa A spermatozoon (; also spelled spermatozoön; ; ) is a motile sperm Sperm is the male reproductive Cell (biology), cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and ...
, from the penis. The most common form of genital alteration is
circumcision Circumcision is a procedure that removes the foreskin from the human penis. In the most common form of the operation, the foreskin is extended with forceps, then a circumcision device may be placed, after which the foreskin is excised. Top ...
, the removal of part or all of the foreskin for various cultural, religious, and more rarely medical reasons. There is controversy surrounding circumcision. , a
systematic review A systematic review is a scholarly synthesis of the evidence on a clearly presented topic using critical methods to identify, define and assess research on the topic. A systematic review extracts and interprets data from published studies on t ...
of 15,521 men, who were measured by health professionals rather than themselves, concluded that the average length of an erect human penis is 13.12 cm (5.17 inches) long, while the average circumference of an erect human penis is 11.66 cm (4.59 inches).


Marsupials

Most marsupials, except for the two largest species of kangaroos and marsupial moles (assuming the latter are true marsupials), have a bifurcated penis, separated into two columns, so that the penis has two ends corresponding to the females' two vaginas.


Monotremes

Monotreme Monotremes () are prototherian mammals of the order Monotremata. They are one of the three groups of living mammals, along with placentals (Eutheria), and marsupials (Metatheria). Monotremes are typified by structural differences in their brains, ...
s and marsupial moles are the only mammals in which the penis is located inside the cloaca. Male
echidna Echidnas (), sometimes known as spiny anteaters, are quill-covered monotremes (egg-laying mammals) belonging to the Family (biology), family Tachyglossidae . The four Extant taxon, extant species of echidnas and the platypus are the only livin ...
s have a bilaterally symmetrical, rosette-like, four-headed penis. During mating, the heads on one side "shut down" and do not grow in size; the other two are used to release semen into the female's two-branched reproductive tract. The heads used are swapped each time the mammal copulates.Augee, Gooden and Musser, p. 81. When not in use, the penis is retracted inside a preputial sac in the cloaca. The male echidna's penis is long when erect, and its shaft is covered with penile spines. The penis is nearly a quarter of his body length when erect.


Others

The penis of the bush hyrax is complex and distinct from that of the other hyrax genera. It has a short, thin appendage within a cup-like glans penis and measures greater than when erect. Additionally, it has been observed that the bush hyrax also has a greater distance between the anus and preputial opening in comparison to other hyraxes. An adult elephant has the largest penis of any land animal. An elephant's penis can reach a length of and a diameter of at the base. It is S-shaped when fully erect and has a Y-shaped orifice. During
musth Musth or must (from Persian, )''The Oxford Dictionary and Thesaurus: American edition'', published 1996 by Oxford University Press; p. 984 is a periodic condition in bull (male) elephants characterized by aggressive behavior and accompanied by ...
, a male elephant may urinate with his penis still in the sheath, which causes the urine to spray on the
hind legs A hindlimb or back limb is one of the paired articulated appendage An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homolog ...
.Sukumar, pp. 100–08. An elephant's penis is very mobile, being able to move independently of the male's pelvis, and the penis curves forward and upward prior to mounting another elephant. In giant anteaters, the (retracted) penis and testes are located internally between the rectum and
urinary bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...
. When the male armadillo '' Chaetophractus villosus'' is sexually aroused, species determination is easier. Its penis can be as long as , and usually remains completely withdrawn inside a skin receptacle. Scientists conducting studies on the ''C. villosus'' penis muscles revealed this species' very long penis exhibits variability. During its waking hours, it remains hidden beneath a skin receptacle, until it becomes erect and it projects outside in a
rostral Rostral may refer to: Anatomy * Rostral (anatomical term), situated toward the oral or nasal region * Rostral bone, in ceratopsian dinosaurs * Rostral organ, of certain fish * Rostral scale The rostral scale, or rostral, in snakes and other Sq ...
direction.


Fish and reptiles

Male
turtle Turtles are an order (biology), order of reptiles known as Testudines, characterized by a special turtle shell, shell developed mainly from their ribs. Modern turtles are divided into two major groups, the Pleurodira (side necked turtles) an ...
s and
crocodile Crocodiles (family (biology), family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to inclu ...
s have a penis, while male specimens of the reptile order
Squamata Squamata (, Latin ''squamatus'', 'scaly, having scales') is the largest Order (biology), order of reptiles, comprising lizards, snakes, and amphisbaenians (worm lizards), which are collectively known as squamates or scaled reptiles. With over 1 ...
have two paired organs called hemipenes.
Tuatara Tuatara (''Sphenodon punctatus'') are reptiles endemic to New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ...
s must use their cloacae for reproduction. Due to evolutionary convergence, turtle and mammal penises have a similar structure. In some fish, the
gonopodium Fins are distinctive anatomical features composed of bony spine (zoology), spines or Ray (fish fin anatomy), rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bon ...
, andropodium, and
clasper In biology, a clasper is a male anatomical structure found in some groups of animals, used in mating. Male cartilaginous fish have claspers formed from the posterior portion of their pelvic fin which serve to channel semen into the female's c ...
s are intromittent organs (to introduce sperm into the female) developed from modified fins.


Invertebrates


Arthropods

The record for the largest penis size to body size ratio is held by the
barnacle A barnacle is a type of arthropod constituting the subclass (taxonomy), subclass Cirripedia in the subphylum Crustacean, Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tid ...
. The barnacle's penis can grow to up to forty times its own body length. This enables them to reach the nearest female for fertilization. A number of invertebrate species have independently evolved the mating technique of traumatic insemination where the penis penetrates the female's abdomen, thereby creating a womb into which it deposits sperm. This has been most fully studied in
bed bug Bed bugs are insects from the genus ''Cimex'' that feed on blood, usually at night. Their bites can result in a number of health impacts including skin rashes, psychological effects, and allergy, allergic symptoms. Bed bug bites may lead to ski ...
s. Some
millipede Millipedes are a group of arthropods that are characterised by having two pairs of jointed arthropod leg, legs on most body segments; they are known scientifically as the class (biology), class Diplopoda, the name derived from this feature. Each ...
s have penises. In these species, the penis is simply one or two projections on underneath the third body segment that produce a
spermatophore A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores ...
or sperm packet. The act of insemination, however, occurs through specialized legs called
gonopods Gonopods are specialized appendage An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism's body. In arthropods, an appendage refers to any of the homology (biology), homologous body par ...
which collect the spermatophore and insert it into the female.


Insects

In male
insect Insects (from Latin ') are pancrustacean Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, Thorax (ins ...
s, the structure analogous to a penis is known as aedeagus. The male copulatory organ of various lower invertebrate animals is often called the ''cirrus''. The lesser water boatman's
mating call A mating call is the auditory signal used by animals to attract mates. It can occur in males or females, but literature is abundantly favored toward researching mating calls in females. In addition, mating calls are often the subject of mate choic ...
, generated by rubbing the penis against the
abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
, is the loudest sound, relative to body size, in the animal kingdom. In 2010, entomologist Charles Linehard described '' Neotrogla'', a new genus of barkflies. Species of this genus have sex-reversed genitalia. Females have penis-like organs called gynosomes that are inserted into vagina-like openings of males during mating. In 2014, a detailed study of the insects reproductive habits led by Kazunori Yoshizawae confirmed that the organ functions similar to a penis – for example, it swells during sexual intercourse – and is used to extract sperm from the male.


Mollusks

The penis in most male
Coleoid Subclass Coleoidea, or Dibranchiata, is the grouping of cephalopod A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine ...
cephalopods A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...
is a long and muscular end of the gonoduct used to transfer spermatophores to a modified arm called a
hectocotylus A hectocotylus (plural: ''hectocotyli'') is one of the cephalopod limb, arms of male cephalopods that is specialized to store and transfer spermatophores to the female. Structurally, hectocotyli are muscular hydrostats. Depending on the species, t ...
. That, in turn, is used to transfer the spermatophores to the female. In species where the hectocotylus is missing, the penis is long and able to extend beyond the mantle cavity and transfers the spermatophores directly to the female. Deepwater squid have the greatest known penis length relative to body size of all mobile animals, second in the entire animal kingdom only to certain sessile
barnacle A barnacle is a type of arthropod constituting the subclass (taxonomy), subclass Cirripedia in the subphylum Crustacean, Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tid ...
s Penis elongation in '' Onykia ingens'' may result in a penis that is as long as the mantle, head and arms combined.
Giant squid The giant squid (''Architeuthis dux'') is a species of deep-ocean dwelling squid in the family (biology), family Architeuthidae. It can grow to a tremendous size, offering an example of deep-sea gigantism, abyssal gigantism: recent estimates ...
of the genus '' Architeuthis'' are unusual in that they possess both a large penis and modified arm tips, although it is uncertain whether the latter are used for spermatophore transfer.


Etymology

The word "penis" is taken from the
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
word for "
tail The tail is the section at the rear end of certain kinds of animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able t ...
". Some derive that from
Indo-European The Indo-European languages are a language family native to the languages of Europe, overwhelming majority of Europe, the Iranian plateau, and the northern Indian subcontinent. Some European languages of this family, English language, Englis ...
''*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 The ''Oxford English Dictionary'' (''OED'') is the first and foundational historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a com ...
cites an example of the word ''yard'' used in this sense from 1379, and notes that in his ''Physical Dictionary'' of 1684, Steven Blankaart defined the word ''penis'' as "the Yard, made up of two nervous Bodies, the Channel, Nut, Skin, and Fore-skin, etc." According t
Wiktionary
this term meant (among other senses) "rod" or "bar". As with nearly any aspect of the body involved in sexual or excretory functions, the penis is the subject of many
slang Slang is vocabulary (words, phrases, and usage (language), linguistic usages) of an informal register, common in spoken conversation but avoided in formal writing. It also sometimes refers to the language generally exclusive to the members of p ...
words and
euphemism A euphemism () is an innocuous word or expression used in place of one that is deemed Profanity, offensive or suggests something unpleasant. Some euphemisms are intended to amuse, while others use bland, inoffensive terms for concepts that the us ...
s for it, a particularly common and enduring one being "cock". See WikiSaurus:penis for a list of alternative words for penis. The Latin word ''"
phallus A phallus is a penis (especially when Erection, erect), an object that resembles a penis, or a mimesis, mimetic image of an erect penis. In art history a figure with an erect penis is described as ithyphallic. Any object that symbolically— ...
"'' (from
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
φαλλος) is sometimes used to describe the penis, although "phallus" originally was used to describe ''representations'', pictorial or carved, of the penis.


Heraldry

Pizzles are represented in
heraldry Heraldry is a discipline relating to the design, display and study of armorial bearings (known as armory), as well as related disciplines, such as vexillology, together with the study of ceremony, Imperial, royal and noble ranks, rank and genealo ...
, where the adjective ''pizzled'' (or ''vilené'') indicates that part of an animate charge's anatomy, especially if coloured differently.


See also

* Buried penis *
Castration anxiety Castration anxiety is the fear of emasculation in both the literal and metaphorical sense. Castration anxiety is an overwhelming fear of damage to, or penis removal, loss of, the penis—one of Sigmund Freud's earliest psychoanalytic theories. Al ...
*
Dildo A dildo is a sex toy, often explicitly Phallus, phallic in appearance, intended for sexual penetration or other sexual activity during masturbation or with sex partners. Dildos can be made from a number of materials and shaped like an erect hu ...
* Diphallia *
Erogenous zone An erogenous zone (from Greek , ''érōs'' "love"; and English ''-genous'' "producing", from Greek , ''-genḗs'' "born") is an area of the human body that has heightened Sensitivity (human), sensitivity, the sexual stimulation, stimulation of w ...
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Fascinus In Religion in ancient Rome, ancient Roman religion and Magic in the Greco-Roman world, magic, the ''fascinus'' or ''fascinum'' was the embodiment of the divine phallus. The word can refer to phallus effigy, effigies and amulets, and to the spel ...
* Koteka *
Micropenis Micropenis is an unusually small Human penis, penis. A common criterion is a dorsal (measured on top) Human penis size, penile length of at least 2.5 standard deviations smaller than the mean human penis size (stretched penile length less than ...
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Penis enlargement Penis enlargement, or male enhancement, is any technique aimed to increase the Human penis size, size of a human penis. Some methods aim to increase total length, others the shaft's girth, and yet others the glans penis, glans size. Techniques i ...
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Penis envy Penis envy (german: Penisneid) is a stage theorized by Sigmund Freud Sigmund Freud ( , ; born Sigismund Schlomo Freud; 6 May 1856 – 23 September 1939) was an Austrian neurologist and the founder of psychoanalysis, a clinical method for eval ...
* Penis removal *
Phallic architecture Phallic architecture consciously or unconsciously creates a symbolic representation of the phallus, human penis. Buildings intentionally or unintentionally resembling the human penis are a source of amusement to locals and tourists in various plac ...
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Preputioplasty Preputioplasty or prepuce plasty, also known as "limited dorsal slit with transverse closure", is a plastic surgical operation on the prepuce or foreskin In male Human body, human anatomy, the foreskin, also known as the prepuce, is the doubl ...
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Pubic hair Pubic hair is terminal hair, terminal body hair that is found in the sex organ, genital area of adolescent and adult humans. The hair is located on and around the sex organs and sometimes at the top of the inside of the thighs. In the pubic reg ...
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Stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filame ...
* Stunt cock *
Testicle A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is Homology (biology), homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, pr ...


References


Citations


General and cited references


Horses

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Marsupials

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Other animals

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External links


Kinsey Institute on the penis
{{Authority control Animal male reproductive system Articles containing video clips Sex organs