The penile morphology of some types of strepsirrhine primates has provided information about their taxonomy. [108] Male galago species possess very distinctive penile morphology that can be used to classify species. [109] [110] [111]

Carlson, Neil. (2013). Physiology of Behavior. Upper Saddle River, New Jersey: Pearson Education, Inc. In support of ejaculate adjustment, research has shown that a male typically increases the amount he inseminates sperm into his partner after they have been separated for a period of time. [47] This is largely due to the fact that the less time a couple is able to spend together, the chances the female will be inseminated by another male increases, [48] hence greater sperm competition. Increasing the number of sperm a male inseminates into a female acts to get rid of any rival male's sperm that may be stored within the female, as a result of her potential extra-pair copulations (EPCs) during this separation. Through increasing the amount he inseminates his partner following separation, a male increases his chances of paternal certainty. This increase in the number of sperm a male produces in response to sperm competition is not observed for masturbatory ejaculates. [34] Quality In 2009, researchers Chen, Eberli, Yoo and Atala have produced bioengineered penises and implanted them on rabbits. [81] The animals were able to obtain erection and copulate, with 10 of 12 rabbits achieving ejaculation. This study shows that in the future it could be possible to produce artificial penises for replacement surgeries or phalloplasties. In 2015, the world's first successful penis transplant took place in Cape Town, South Africa in a nine-hour operation performed by surgeons from Stellenbosch University and Tygerberg Hospital. The 21-year-old recipient, who had been sexually active, had lost his penis in a botched circumcision at 18. [82] Additional imagesThe photographs are properly marked SAFE or RESTRICTED (18+ only / nudity). There IS NO porn nor stolen photos !

Some people find a penis sexy or beautiful in itself, others don’t, but none of the people we asked believe you have to be attracted to penises to be attracted to men. So you don’t need to question your sexuality just because you’re not deeply aroused by someone’s knob. Male Circumcision and Risk for HIV Transmission and Other Health Conditions: Implications for the United States". Centers for Disease Control and Prevention. 2008. Archived from the original on 2017-02-20 . Retrieved 2013-11-07. Blood vessels may expand to regulate heat and contract in reaction to cold, which may give your penis the appearance of a larger size in the summer. The penis in most male Coleoid cephalopods is a long and muscular end of the gonoduct used to transfer spermatophores to a modified arm called a hectocotylus. 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 barnacles Penis elongation in Onykia ingens may result in a penis that is as long as the mantle, head and arms combined. [146] [147] Giant squid 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. [146] Etymology

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. [143] 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. [144] [145] Mollusks The human penis is made up of three columns of tissue: two corpora cavernosa lie next to each other on the dorsal side and one corpus spongiosum lies between them on the ventral side. The urethra, which is the last part of the urinary tract, traverses the corpus spongiosum, and its opening, known as the meatus / m iː ˈ eɪ t ə s/, lies on the tip of the glans penis. It is a passage both for urine and for the ejaculation of semen. The glans penis of the marsh rice rat is long and robust, [91] averaging 7.3mm ( 9⁄ 32in) long and 4.6mm ( 3⁄ 16in) broad, and the baculum (penis bone) is 6.6mm ( 1⁄ 4in) long. [92] As is characteristic of Sigmodontinae, the marsh rice rat has a complex penis, with the distal (far) end of the baculum ending in three digits. [93] The central digit is notably larger than those at the sides. [91] 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 and Oryzomys couesi among oryzomyines examined. [94] On the urethral process, located in the crater at the end of the penis, [95] a fleshy process (the subapical lobule) is present; it is absent in all other oryzomyines with studied penes except O.couesi and Holochilus brasiliensis. [96] The baculum is deeper than it is wide. [91]

Masters, W. H.; Johnson, V. E. (1966). Human Sexual Response. Boston: Little, Brown and Company. ISBN 9780316549875.Monotremes and marsupial moles are the only mammals in which the penis is located inside the cloaca. [123] [124] a b c d e f Mautz, B. S.; Wong, B. B. M.; Peters, R. A.; Jennions, M. D. (April 23, 2013). "Penis size interacts with body shape and height to influence male attractiveness". Proceedings of the National Academy of Sciences of the United States of America. 110 (17): 6925–30. Bibcode: 2013PNAS..110.6925M. doi: 10.1073/pnas.1219361110. JSTOR 42590540. PMC 3637716. PMID 23569234. While over the years Jeremy’s hirsute and rotund physique has earned him the moniker “The Hedgehog,” as a younger, slimmer man, he was able to autofellate himself. No small feat, surely. Kilgallon, Sarah J.; Simmons, Leigh W. (2005-09-22). "Image content influences men's semen quality". Biology Letters. 1 (3): 253–255. doi: 10.1098/rsbl.2005.0324. ISSN 1744-9561. PMC 1617155. PMID 17148180.