Understanding of superorganisms: collective behavior, differentiation and social organization

Most animal species spend their lives in a form based on the unit of “an individual” that is a sophisticated multicellular closed unit with various biological functions. Although the system of an animal individual seems to be perfect, individuals belonging to some animal lineages constitute higher-dimensional units, i.e., colonies, that consist of multiple individuals of the same species, performing divisions of labors among them. Those animals include eusocial insects and colonial animals, and their colonies are also known as “superorganisms”, since a colony behave as a single individual. Recent molecular and genomic/transcriptomic studies have been revealing the regulatory mechanisms underlying the integrated systems of superorganisms although many aspects have yet to be elucidated. In this article, life patterns of superorganisms in some animals are introduced, together with recent research advances on the mechanisms. Furthermore, animal species that show distinctive developmental systems such as abnormal asexual reproduction are also focused, since those developmental patterns are deviated from the concept of normal animal “individuality”. Furthermore, synthetic approaches based on robotics and mathematical modeling, focusing on novel robotic systems that can self-organize various non-trivial macroscopic functionalities as observed in superorganisms, are also discussed.