Lateralization in invertebrates

This chapter discusses the methods of studying behavioral lateralization in invertebrate animals. Although to date not a great deal is known about lateralized behavior and cognitive function in invertebrates, a number of studies have provided evidence of lateralization in a range of invertebrate species. Behavioral asymmetries have been shown in phyla such as Arthropoda (Insecta, Arachida, and Malacostraca), Mollusca (Gastropoda and Cephalopoda) and Nematoda, and in a variety of behaviors. Here I report the findings of research conducted on lateralization in invertebrates with a specific focus on the methodology adopted. Behavioral asymmetries in the invertebrate line have been investigated by observing biases in different types of behavior that can be classified in six main groups corresponding to the six sections of the chapter (summarized in Table 1). These six sections analyze the methods used to investigate lateral biases in (1) catching prey and foraging behavior; (2) escape response; (3) interactions with conspecifics (aggressive and sexual behavior); (4) spontaneous motor behavior (preferential choice in a T-maze); (5) sensory modalities (olfaction, vision, and hearing); and (6) recall of memory associated with conditioning in one of these sensory modalities. For each method the advantages and disadvantages of using it are examined and the main findings are reported and discussed