Squids that appeal with cool “ink” and courtship with “heart marks”. Research suggests that the ink that squids spit out to confuse their enemies and escape is also used in courtship behavior to make themselves stand out white and appeal to females.
A research group led by Arata Nakayama, a graduate student at the University of Tokyo, noticed that when males of the cuttlefish spit out ink while courting females, they touched each other with two special arms.