Earlier this week, we learned that female octopuses sometimes strangle—and then possibly eat—their male mates. For a cannibalistic animal with long arms, perhaps we—and the male—should have seen that one coming. (Especially since the female apparently had already gotten what she needed out of the rendezvous.)
But an additional report finds that octopus strangulation is not always tied up in sex. And sometimes it is used against other octopus species entirely. Researchers Christine Huffard and Mike Bartick recently described a surprising encounter of two stunning species in the waters of the Philippines.
Bartick was diving near Mabini in the Philippines, observing a mimic octopus (Thaumoctopus mimicus), which was apparently minding its own business foraging for food. Suddenly, however, a wonderpus octopus (yes that really is its name; Wunderpus photogenicus)—which looks like and behaves similarly to the mimic octopus—entered onto the scene.
The wonderpus "rapidly approached and engaged [the mimic octopus] in a series of physically aggressive interactions," the researchers recount. "Each time the [mimic octopus] escaped and reached a distance of approximately one meter, the [wonderpus] pursued it and reengaged aggression."
One of these attacks included the wonderpus wrapping its second right (and longest) arm around the mantle of the mimic octopus—right by the funnel. Despite being smaller overall, the wonderpus had a longer arm span than the mimic octopus, here giving it the advantage. The altercation was described earlier this month in Molluscan Research.
With one of its extra long arms, the wunderpus "formed a loop around the mantle of the other octopus near the mantle and tightened the loop," the researchers explain.
"This behavior is superficially similar to constriction in snakes," Bartick and Huffard write. But "unlike in snakes, constricting in octopuses does not interfere with breathing by the aggressor." Strangling here prevents "the flow of water into the mantle and out of the funnel"—the way these animals circulate water over their gills to oxygenate their blood. "So constricting would lead to oxygen depletion and ultimately death."
This stranglehold might also keep the holdee from unleashing its ink—an irritant that can be used to deter attackers—by preventing water from being expelled through the funnel.
Aside from the startling behavior, this encounter also helps scientists understand the dynamics of this ecosystem more broadly. With such similar octopus species living—and hunting—in the same area, there is bound to be some competition. (Although, generally, mimic octopuses are daytime feeders, and wunderpuses come out at dusk.) And this exchange documents one of the advantages that the smaller wonderpus species has in this on-going battle: long arms.
Unlike was the fate for the strangled male day octopus, which became is mate's dinner after their brief date, both of these octopuses survived—if only because of a little "diver interference."
Check out some of the other crazy things octopuses can do with their arms inOctopus! The Most Mysterious Creature In the Sea.