Basement of squid sociality expressed with social network in the oval squid school

Abstract

Cephalopod have large brain, lens eyes and numerous chromatophore. They accomplish observational learning with this information processing system. In spite of sharing the well-developed system, there are big variations for their cognitive ability among octopus and squid. Solitary and benthic octopus should have good spatial cognition with their long arms. On the other hand, gregarious and nektonic squid should have good communication ability with school members. Although knowledge about inter-individual relationship of squids will help deep understanding of communication, there are few information about schooling behavior of squid despite much accumulation of knowledge about octopus cognitive ability. This article reviews studies for schooling behavior of oval squid, Sepioteuthis lessoniana. Through social network analysis, basic structure of their inter-individual relationship is uncovered. Understanding of communication for squid with the knowledge about schooling behavior will contribute to understand evolution of cephalopod cognitive ability.