Heart rate measures in blind cave crayfish during environmental disturbances and social interactions

Most animals continually assess the environment in which they live and alte r their behavior according to various stimuli. As an observer, one looks fo r changes in a behavior indicating that an animal responded to a particular event. When the animal does not make significant behavioral changes as mea sured by bodily movements, the animal may be characterized as unresponsive to a given stimulus. This study demonstrates that when behavioral body move ments can not be observed an internal physiological measure of heart rate ( HR) shows dramatic changes following presentation of defined stimuli. This study used the blind cave crayfish and examined their responsiveness to the following stimuli: light (infrared, dim red, and white), water-borne vibra tions, removal of water, olfactory cues, and social interaction with partne rs. This study demonstrates that there is substantial individual variation of HR at basal levels and with the intensity of an social interaction. We f ind HR is a reasonable measure of the responsiveness of blind cave crayfish to given stimuli even in the absence of observable behavioral changes. Thi s enables the observer to determine if an individual is responsive to and m aking an assessment of particular cues. (C) 2000 Elsevier Science Inc. All rights reserved.