Photo of two flatworms captured just before penis fencing.

“Penis fencing” is a marine flatworm (Platyhelminthes) mating behaviour where two flatworms “fence” in order to pierce and inject sperm into their mate’s skin. This hypodermic insemination of sperm is vital to the reproduction of the Platyhelminthes phylum. 

Local oceanography teacher Jerry Marlin says that he has discovered a new way to properly teach this concept in his classes: “Usually kids get pretty bored during the marine invertebrate unit and after years of teaching. I’ve realized that the trick is hands-on learning.” 

Every April when the syllabus hits the penis fencing section, Marlin engages his students in a tactical lab, where each student gets a chance to be both a fencer and fencee. 

“I demonstrate first, of course,” Marlin explains. “The student with the highest grade is chosen to be my partner. Then everybody pairs up, unbuttons, and starts scrimmaging.” 

Marlin says that since he has introduced this new teaching method, he has become much closer with his students. However, he has experienced some backlash, 

“I get angry calls from parents,” Marlin says. “They call me a ‘pedagogue,’ whatever that means.”

For more information, lesson plans, maps, and resources for your very own penis fencing pedagogy, check out https://www.nationalgeographic.org/education/classroom-resources/

—T. Bhat