The term penis applies to many intromittent organs , 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. 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 the penis bears the distal part of the urethra , which discharges both urine during urination and semen during copulation. Most male birds e.
The Origin of the Penis: Where Did It Come From?
Penis - Wikipedia
By Cerina M. Karr, Biology, Therefore, it is essential that genitalia are kept intact so that organisms may produce offspring. Why, then, is human male genitalia so vulnerable? What are the options? An important distinction to make is that while the penis is an external organ, fertilization itself is an internal process in humans. Tailless amphibians, such as frogs, fertilize externally.
Mystery solved: Where the penis comes from
Anonymous, age and sex unspecified Dear Carole, Why are women so obsessed with the size of a man's cock — wanting ones 6 inches and over and kicking others aside when they really should be concentrating on the emotional connection and love being shared, putting the size of the man's cock right out of her mind? Carole replies: The origins of the primate sex drive go back more than 60m years to the late Mesozoic era when the first primate evolved. A lot of sex has taken place since then, and a significant proportion has been motivated by female choice between rival males.
The following essay is reprinted with permission from The Conversation , an online publication covering the latest research. One of the most weird and wonderful products of evolution is the penis bone, or baculum. The baculum is an extra-skeletal bone, which means it is not attached to the rest of the skeleton but instead floats daintily at the end of the penis. Depending on the animal, bacula range in size from under a millimetre to nearly a metre long, and in shape, varying from needle-like spines to fork like prongs.