Greg Marshall

Novel insights into green sea turtle behaviour using animal-borne video cameras

An animal-borne video camera and data-logger was used to collect behavioural data on green (Chelonia mydas) and loggerhead (Caretta caretta) turtles in Western Australia. This technique provided novel insights into the behaviour of green turtles including an apparent self-cleaning behaviour. Also, ctenophores and jelly¢sh might be more important in the diet of these turtles than previously thought.

Insights into the Underwater Diving, Feeding, and Calling Behavior of Blue Whales from a Suction-Cup-Attached Video-Imaging Tag (CRITTERCAM)

Abstract : We examined the underwater behavior of blue whales using a suction-cup-attached video-imaging instrument (CRITTERCAM). We made 13 successful deployments (defined as tag duration of 15 min and successful recovery of the tag and data) totaling 19 hours of CRITTERCAMs on blue whales off California and in the Sea of Cortez from spring through fall (26 February to 30 September) between 1999 and 2003 . Whale diving depth and behavior varied widely by region and period, although deployments on different individuals in the same area and period often showed very similar feeding behavior. One deployment extending into night showed a diurnal shift in diving behavior with progressively shallower feeding dives as it became dark, with shift to shallow, apparently non-feeding dives during the night. Data and video from tags demonstrated that the characteristic series of vertical movements blue whales make at depth are lunges into dense aggregations of krill. These krill were visible streaming by the camera immediately before these lunges and more clearly when the whales? forward motion stopped as a result of the lunge. The progression of events leading up to and during the lunge could be documented from the head movement of whales and occasional views of the expanding throat pleats or lower jaw, and by changes in flow noise past the tag, indicating a rapid deceleration. One set of deployments in the Southern California Bight revealed consistent feeding at depths of 250-300 m, deeper than has been previously reported for blue whales. A loud blue whale vocalization was heard on only one deployment on a male blue whale in an interacting trio of animals.

Are mantas self aware or simply social? A response to Ari and D’Agostino 2016

Manta rays have captured the interest of the public and scientists alike because of their large size, gentle demeanor, graceful nature, and, perhaps above all, their inquisitiveness and perceived intelligence. There is much evidence to suggest that manta rays are intelligent species, with the largest brains of any fish (Ari 2011) and highly derived adaptations, such as countercurrent brain warming mechanisms (Alexander 1996). While the evidence does indeed suggest that manta rays have the capacity for unusual intelligence in a fish, there is a lingering question as to just how smart manta rays truly are. Ari and D’Agostino (2016) attempt to shed light on this question by experimentally testingwhether or notmanta rays can identify themselves in a mirror—in a first attempt to lay the groundwork for identifying self-awareness in a fish species. The study examines activity levels and behavioral responses by captive manta rays in the presence of a mirror, in the presence of a white board (experimental control), and in the absence of both a mirror and a white board (blank control). The authors demonstrate convincingly that the two mantas in the study were more active and spent more time in front of the mirror as compared with the controls. When in front of the mirror, the mantas also made frequent and repetitive movements, furling and unfurling their cephalic lobes. The authors interpreted this behavior as contingency checking, in which the animal makes repeated movements and tests to see if the visible image moves when the animal moves. One of the animals also exposed its ventral side to the mirror, which the authors interpreted as self-directed behavior, where the animal investigates a body part that would not otherwise be visible without the aid of the mirror. The authors use the results of similar studies in apes to suggest that the observed behaviors may indicate self-recognition: ‘‘In apes, SD behavior in response to a mirror has been taken as evidence of selfrecognition (Prior et al. 2008); therefore, the recorded observations on manta rays possibly show their ability to self-awareness.’’ While the authors stop short of declaring self-awareness in manta rays, they strongly imply that their results are the first step in identifying self-awareness for the first time in a fish species. Unfortunately, the authors do not simply ignore, but actively dismiss a much more plausible explanation for the observed behaviors: that the captive mantas perceive the image in the mirror as another individual and are engaging in social behaviors when the mirror is present. A previous study by one of the authors (Ari 2014) found that manta rays in captivity can rapidly change the shade of their dorsal markings, and on at least one occasion the author observed a manta exhibiting color changes upon This comment refers to the article available at doi:10.1007/s10164016-0462-z.