National Geographic : 2015 Apr
PHOTOS: JOEL SARTORE Photos of the gray-banded king snake (Lampropeltis alterna) were shot at Texas’ Fort Worth Zoo. A genteel disquisition on love and lust in the animal kingdom Basic Instincts Drawing his chin along her skin. Coiling his body about hers. Jerking his head seductively, biting her, and vibrating his tail. In the Kama Sutra of snake sex, these are prime mating moves among colubroids, the world’s largest family grouping of snakes with some 2,500 species. To see how snake courtship evolved, herpetologist and paleontolo- gist Phil Senter studied data on 76 snakes of the Colubroidea and Boidae groups. From research that included studies of fossil records dating to the Cretaceous period, he found that some colubroid come- ons are ancient—chin-rubbing, jerking—while the “coital bite” and “tail quiver” began later. In all, he says, it’s “quite the set of dance moves.” The snake-atop-snake courtship position called mounting is “nearly universal” in the species studied, Senter wrote in the journal PLOS ONE. However, he noted with clinical delicacy, mounting is not required for “intromission,” aka copulation. To mate, snakes need only to align the base of their tails at the cloaca, an opening serving both reproductive and excretory systems. The male extends his hemipenes, the two-pronged sex organ stored in his tail, and with each half depos- its sperm into the female’s cloaca. The sex act can last for hours, Senter says—commonly, longer than the courtship. —Patricia Edmonds Snakes’ Charming Moves RANGE Mexico, southwestern U.S. CONSERVATION STATUS Least concern OTHER FACTS Gray-banded king snakes (seen here) as well as rat, corn, and garter snakes be- long to the superfamily Colu- broidea. Boas and anacondas belong to the family Boidae.