Oral sex is an exceptionally intimate act. There are different names for it, such as Blow Job, Fellatio or Head Job. Regardless how you name it, just the idea of sucking and licking intimate parts makes sexual act more exciting and desirable.
When you are talking about oral sex, it is usually associated with human foreplay. But what a surprise it was for me to find out, that oral sex has been documented for the short-nosed fruit bat Cynopterus sphinx. Female bat licks the mate’s penis during sex! This is how it is reported in a study by scientists Tan M, Jones G, Zhu G, Ye J, Hong T, named “Fellatio by Fruit bats Prolongs Copulation”

“The female lowers her head to lick the shaft or the base of the male’s penis but does not lick the glans penis which has already penetrated the vagina. Males never withdrew their penis when it was licked by the mating partner. A positive relationship exists between the length of time that the female licked the male’s penis during copulation and the duration of copulation. Furthermore, mating pairs spent significantly more time in copulation if the female licked her mate’s penis than if fellatio was absent. Males also show postcopulatory genital grooming after intromission.”