Can animals really be gay?

Octopoteuthis deletron isn’t picky. Combing through ROV video footage of the cephalopods taken over the last two decades, researchers found evidence of same-sex mating behaviors just as often as opposite-sex mating. For these invertebrates, observed 1,300 to 2,600 feet below the surface, mating means shooting a packet of sperm-containing sacs onto a partner. Sperm enters through the skin and is stored inside the female’s body until fertilization.

Of the 39 squid whose sex could be identified on the videos, nine males and 10 females had sperm sacs attached to their bodies. But the finding doesn’t make some male squid gay or bi, lead author Hendrik Hoving told the New York Times. Rather than preferring males over females, or seeking out both equally, the squid simply take a literal shot in the dark in hopes of scoring a viable mate. “Apparently, the costs involved in losing sperm to another male are smaller than the costs of developing sex discrimination and courtship, or of not mating at all,” the study authors wrote.

(The pictured squid is not O. deletron.)

Same-sex sexual behavior is well documented in monkeys and apes, and bonobos, our closest relatives (alongside chimps) are a study in bisexuality. A whopping 50 percent or so of bonobo sexual encounters across all ages are same-sex. Female bonobos partake in same-sex genital rubbing once every two hours or so, often leading to orgasm, Stanford University biologist Joan Roughgarden writes in Evolution’s Rainbow: Diversity, Gender, and Sexuality in Nature and People, and an average of two thirds of their sexual encounters are with other females. Males also swing both ways, so to speak, although with less frequency. They participate in oral and manual stimulation, “rump rubbing,” “penis fencing” and even French kissing.

Bonobo society (unlike that of chimps) is female-dominated, and lesbian sex helps form coalitions against males and welcomes new members into the group. These alliances help females of the species reproduce earlier than chimps, leading to higher lifetime reproduction success. “For a female bonobo, not being a lesbian is hazardous to your fitness,” Roughgarden writes. An evolutionary advantage is harder to theorize for female Japanese macaques, which don’t seem to use gay sex to form alliances, to get parenting help, as an expression of dominance or submission, or because opposite sex partners are scarce. These monkeys may do it just for pleasure, and because they still procreate frequently, the effect on the species is neutral.

Humboldt, king, gentoo and Adélie penguins have been observed mounting same-sex partners (to climax) and participating in other same-sex sexual behaviors. Some male Humboldt penguins maintain lifelong homosexual pair bonds, never mating with a female. In 2004, Roy and Silo, two 18-year-old chinstrap penguins at Manhattan’s Central Park Zoo, drew headlines for their same-sex relationship. Although the two didn’t copulate, the New York Times reported that they shared “mating rituals like entwining their necks and vocalizing to one another,” in a pair bond that began in 1998. The duo took no notice of females in the enclosure, building a nest together and hatching an extra egg from a heterosexual penguin pair after an unsuccessful attempt to incubate a rock.

Tango, their adopted chick, went on to find her own same-sex partner, Tazuni. Roy and Silo eventually divorced (a term used by biologists to describe broken pair bonds), but similar male penguin pairs attempting to incubate chicks have also been reported at zoos in San Francisco, Germany and China.