The penis (Brazilian Portuguese) or penis (European Portuguese) (from the Latin penis, "brush"), also known as phallus and phallus, is the sexual organ of male individuals, among vertebrates or invertebrates that have sexual organs. In humans, its shape is cylindrical, being formed by two types of tissue (two cavernous bodies and a spongy body) and, at its end, there is a slit, which is the end of the urethra, a channel that drains sperm and urine. It is, therefore, an organ that acts in two functions: reproduction and excretion.
The term "penis" applies to many analogous organs of different animals, but not all. For example, the meddling organ of most cephalopods is the hectocotylus, a specialized tentacle, and male spiders use their pedipalps. Even within vertebrates there are morphological variants with specific terminology, such as hemipenes.
In most animal species where there is an organ that could reasonably be described as a penis, the function is only the transmission of sperm to the female, but in placental mammals the penis supports the distal part of the urethra, which discharges so much urine, during urination, how much is used to perform copulation.
In different animals
Many male birds (eg, cocks and turkeys) have a cloaca (also present in females) but not a penis. Among the species of birds with penises are paleognathos and Anatidae (Ducks, geese and swans). A bird's penis is different in structure from a mammal's penis, being an erectile expansion of the cloacal wall and being lifted by lymph, not blood. It is usually partially feathered and in some species it has thorns and filaments, and in a flaccid state it curls inside the cloaca. The thorn-tailed teal has the largest penis in relation to body size among all vertebrates; while generally about half the body size (20 cm), a specimen with a penis 42.5 cm in length is documented.
While most male birds do not have external genitalia, male waterfowl (Anatidae) do have a phallus. Most birds mate with males balancing on females and touching cloacas in a "cloacal kiss"; This makes sexual coercion very difficult. The phallus that male waterfowl evolved out of their bodies (in a clockwise coil) assists them in inseminating females without their cooperation. The male waterfowl evolution of a phallus to vigorously copulate with females has led to counter-adaptations in females in the form of vaginal structures called dead-end sacs and clockwise coils. These structures make it more difficult for males to achieve meddling. Clockwise coils are significant because the male phallus moves away from your body in a counterclockwise spiral; Therefore, a clockwise vaginal structure would prevent forced copulation. Studies have shown that the longer the male phallus, the more elaborate are the vaginal structures. The thorn-tailed teal is notable for having, relative to body length, the largest penis of all vertebrates; The penis, which is normally curled in a flaccid state, can reach about the same length as the animal itself when fully erect, but is more commonly about half the length of the bird. It is theorized that the remarkable size of their bristly-tipped penises may have evolved in response to competitive pressure in these highly promiscuous birds, removing sperm from previous matings in the form of a brush brush.
Male and female emus are similar in appearance, although the male's penis may become visible when defecating. The male tinamou has a corkscrew-shaped penis similar to that of ratites and