Laterality is defined as the occurrence of each cerebral hemisphere having asymmetric control over the different sides of the body, leading to preferences to use one side of the body over the other for various behaviors. Many types of laterality exist, but handedness is the form that is most predominantly assessed. Handedness in animals is of special interest to laterality researchers, as humans were once thought to be the only species that exhibited lateralized hand preferences. The aim of the current study was to determine if Asian small-clawed otters (Aonyx cinerea) exhibit significant paw preferences in behaviors associated with completing a specific tool-use task. Video data of the otters completing the task was analyzed for specific paw interactions with the tool-use apparatus, and the percentage of correct completion of the task was documented for each otter. Overall, no significant population level paw preference was present. However, individual differences in paw preference and differing trends in handedness on each focal behavior was present.  The results showed that paw preference (or lack thereof) did affect the tool-use task completion for some otters, and for others, the preference did not seem to have an effect. The main implications of this study are that paw preferences in Asian small-clawed otters are present on an individual level when solving a novel tool-use task. 

Asian small-clawed otters ( Aonyx cinerea ) demonstrate remarkable hand dexterity when gathering and consuming prey, but little is known about their ability to use objects as tools. The present study used a tool choice paradigm in which six Asian small-clawed otters were tested individually and presented with two identical hook-shaped tools. For each trial, only one tool was positioned such that pulling it allowed an otter to obtain food. Pulling the other hook resulted in the correct hook being moved out of reach, necessitating selection of the correct tool as its first choice The two males performed above chance levels, but the four females did not. The females’ poor overall performance may have reflected their initial inability to understand the tool choice task. Two of the females’ performances improved by 20% over the course of the trials, and another female showed 5% improvement over time. In addition, some incorrect responses appeared to be due to the development of a side preference, rather than to the configuration of the apparatus. Four of the otters exhibited a significant side bias toward the left, but there were individual differences in how these preferences presented in each otter. For all otters, latency to approach and make a choice on the tool-use task decreased over time, regardless of success. Although otters do appear capable of learning which tool should be used in a forced choice comparison such as the one used here, other factors appear to influence the choices individual otters make.

We contest publication of Marino et al. regarding captive killer whale ( Orcinus orca ) welfare because of misrepresentations of available data and the use of citations that do not support assertions. Marino et al. misrepresent stress response concepts and erroneously cite studies, which appear to support Marino et al.’s philosophical beliefs regarding the cetacean hypothalamic–pituitary–adrenal axis. To be clear, these misrepresentations are not differences of scientific opinion, as the authors’ conclusions lack any scientific basis. More extensive review of Marino et al.’s citations reveal a dearth of empirical evidence to support their assertions. Further, Marino et al.’s approach to animal welfare is not consistent with conventional veterinary approaches to animal welfare, including their apparent opposition to use of preventative and therapeutic veterinary interventions. While Marino et al. argue that killer whales’ cognitive and spatial needs preclude management of this species under human care, misrepresentation of the citations used to support this opinion invalidates their arguments. Misleading interpretations of data relative to killer whales’ cognitive and emotional needs and specious and unsubstantiated comparisons with states experienced by humans with posttraumatic stress disorder and other conditions, represent a number of strategies used to misrepresent knowledge regarding killer whale welfare. These misrepresentations and fallacies are inconsistent with scientific ethical standards for credible, peer-reviewed journals (ICMJE, 2018), and are barriers to rigorous discourse and identification of strategies for optimizing killer whale welfare. Assertions in the paper amount to nothing more than a compilation of conclusory, philosophical statements. We would also like to mention that manuscripts such as Marino et al.’s do great damage to the fields of comparative psychology and to behavioral science as a whole.