A Longitudinal Assessment of Temperament in \u3ci\u3eOctopus bimaculoides\u3c/i\u3e

Cephalopods, including Octopus spp., are highly intelligent molluscs that play major roles in many marine food webs, both as top-level feeders (Ambrose, 1984) as well as by constituting a major source of protein for the animals above them (Lang, Hochberg, Ambrose, & Engle, 1997). They also are fascinating organisms for behavioral studies, with elaborate repertoires of behavior based on plasticity and learning (Wells, 1962a; 1962b; 1978) which in complexity rivals that of the vertebrates. The study of individual differences in behavior is a facet of behavioral research that has recently gained attention in the literature (Gosling & John, 1999). Traditionally, behavioral studies previously have been largely based on characterizing groups of animals at the level of the population or species (Slater, 1981). The study of individual variance has risen in importance, however, as we have begun to realize how behavior at the level of the individual contributes to the shaping of the ecological profile of a population (Wilson, Coleman, Clarke, & Biederman, 1993). Octopus bimaculoides (Pickford & McConnaughey, 1949) offers a previously unstudied model of invertebrate individual differences. Individual differences at a young age are considered to be components of an individual\u27s temperament (Rothbart, Ahadi, & Young, 2000), which are behavioral trait dimensions researchers use to describe the traits upon which individuals differ (Buss & Plomin, 1984). Since temperament has not been defined previously for this species, this study first describes temperament at week 3 of life in O. bimaculoides. Secondly, no longitudinal studies have been performed to examine the development of these traits within an invertebrate. The second aspect of this study then examines the development of temperament through week 9 of life. Throughout both aspects of this study, the role of inheritance in these behaviors as well as the analytical methodology used in the study of individual differences is stressed. This study attempts to satisfy some of the need for systematic behavioral development studies in Octopus, while also presenting to those readers of psychology and behavior the first invertebrate model of temperament