Cuttlefish, relatives of octopus and squid, have millions of color cells in their skin, which gives them extraordinary control over their appearance. They are brilliant at camouflage, and they can also create displays to communicate to other cuttlefish.
The males do this when they are fighting over a female. Their battles are primarily visual, flashing a zebra strip display at a rival, or increasing the size of one pupil and creating a dark eye ring. Scientists have seen much of this behavior, but in 2011 off the coast of Turkey two researchers who were diving and observing the common cuttlefish witnessed something much more extreme — a physical battle.
Justine J. Allen of Brown University and Derya Akkaynak, now at the University of Haifa in Israel, recorded video of the fight, which they just released, along with an article in the The American Naturalist describing the encounter.
Dr. Allen said work on her Ph.D. and other projects got in the way of preparing an article on the cuttlefish battle, although they both knew how rare and compelling the fight was. Alexandra K. Schnell of the University of Caen, Normandy, and Roger T. Hanlon of the Marine Biological Laboratory in Woods Hole, Mass., were also authors.
Dr. Allen said this was the first recording of a physical battle between male cuttlefish. Such duels are thought to be rare because of the importance of unmarred skin to creating camouflage and other skin signals.
“They usually do battle with these really beautiful skin displays,” Dr. Allen said.
In the encounter the two researchers recorded, one male is guarding a female after mating. A second male intrudes and actually runs the first male off with his displays. All of this follows a model of gradual escalation, with each testing the other’s size and ability, as such conflicts are supposed to proceed.
But when the second male (the species is Sepia officinalis) tries to mate with the female, the first male comes back and attacks. The two shoot dark brown ink and whirl around in a tangle of tentacles.