Squirting ink may play a role in the copulation of the pygmy squid

Most cephalopods (octopus, squid and cuttlefish) possess an ink sac and their inking behavior is renowned for their anti-predatory defense. The deployment of a small ink cloud by a rapidly moving cephalopod can serve as a decoy that deceives visual predators. Cephalopods can also discharge a significant amount of ink as a smokescreen to startle their enemy and obstruct visual contact, eliminating immediate threats when threatened by predators. Aside from defense purposes, inking by cephalopods serves alternative functions during predation, courtship and agonistic behavior noted by recent studies. Here we show two unique inking behaviors of the pygmy squid which likely increases their mating success rate. The present study suggests that another co-option of inking likely exists in this group of small squid. Digital video images related to the article are available at http://www.momo-p.com/showdetail-e.php?movieid=momo241016ip01a, http://www.momo-p.com/showdetail-e.php?movieid=momo241016ip02a, http://www.momo-p.com/showdetail-e.php?movieid=momo241016ih01a, and http://www.momo-p.com/showdetail-e.php?movieid=momo241016ih02a.