Do animals have oral sex?

Oral sex does occur in the animal kingdom, which is another suggestion that animals enjoy sex and sexual touching – as the behaviour doesn’t appear to have an obvious reproductive purpose.

Non-conceptive sex has been observed in a surprising number of species, but some of the most researched are our closest relatives, primates.

• Do animals enjoy sex? The species seeking pleasure as well as procreation
• Why do so many organisms have sex?

There are several hypotheses for non-conceptive sex, as the encounters don’t appear to have an evolutionary mechanism: the ‘practice-for-heterosexual-sex’ hypothesis, the ‘developmental-by-product’ hypothesis (where traits or behaviours develop as secondary side-effects of other physiological mechanisms) and that these behaviours are motivated by social (rather than sexual) interactions.

Oral sex has also been observed in spotted hyenas, goats and sheep. Fellatio has been documented in fruit bats, with it occurring during copulation. While there are no obvious reasons why this occurs, it was noted that this behaviour significantly increased copulation time.

• What was the first animal to have sex?

A 2014 study showed that two brown bears (raised in captivity) had engaged in recurrent fellatio multiple times a day until they were at least 10 years old. The roles of provider and receiver in the act of oral sex remained consistent, and the behaviour became ritualised. The researchers suggested that the behaviour began because of the deprivation of maternal sucking after the pair were orphaned as cubs.

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Oral sex is rare outside of mammals, but it has been observed in two species of spider: the widow spider and Darwin’s bark spider. In relation to the latter, researchers observed that males salivated onto the females’ genitals before, during and after mating. While they’re not entirely sure why this happens, they’ve theorised that it may signal male quality or reduce sperm competition.

• "After mating he ensures no other suitors follow suit by chewing off his own genitals and uses them to plug the female"

It’s also been recorded in harvestmen (a species of arachnid), with a 2024 study documenting fellatio in 44% of trials. The researchers noted that the behaviour was linked to female unwillingness to mate and shorter copulation times (which is hardly surprising, as the males engage in aggressive behaviour during mating, such as biting and reversed sexual cannibalism).

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