stylistic:tone, structural:scholar_edition, information:extraction, quality:correction
Invertebrates

Harvestmen are the only male arachnids that have a penis.

In male insects, the structure analogous to a penis is known as an aedeagus. The male copulatory organ of various lower invertebrate animals is often called the cirrus.

In 2010, entomologist Charles Linehard described a new genus of barkflies called Neotrogla. 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. A similar female structure has also been described in the closely related Afrotrogla. Scientists who study these insects have occasionally called the gynosome a "female penis" and insisted to drop the definition of penis as "the male copulatory organ". Motivations for using the term “female penis” include that such a term "is easier to understand and much more eye-catching" and that the gynosome have "analogous features" with male penises. Meanwhile, critics have argued that it does not fit the intromittent organ definition of "a structure that enters the female genital tract and deposits sperm".