Analyzed are changes of temporal and amplitude characteristics of the cycles in animals in different functional states, using a non-invasive method of recording of cardiac activity in the adult noble crayfish Astacus astacus L. under laboratory conditions. It has been shown that the state of excitation in the crayfish after action of an intense stimulus lasts for a long time (more than 1 h) and can have no manifestations in some observed behavioral responses. Based only on the cardiac response (the heart rate), the real physiological state of the animal could be evaluated. Characteristic of the excited animal is a short-term response to the stimulus. In a high excitement of the animal (a high heart rate), significant transformations of the heart activity in response to other current stimuli may be barely noticeable. For the quiet animal, the response to a stimulus is longer than for the excited animal at the same stimulus intensity; for a comparative search for significant readjustments of the animal state, based on the heart activity parameters, the cardiograms typical of the quiet animal should be used. In the quiet animals, the cardiogram parameters change to a greater extent than in the excited ones. The quiet animals have longer diastole duration (DD) than the systole duration (SD). The diastole amplitude (DA) is higher than the systole amplitude (SA), and DA changes more markedly than SA. The healthy animals are characterized by equal values of DD and SD, sometimes by longer SD than DD, but, on the background of a continuing action, their values and the values of DA and SA become equal. There were noted a negative correlation between the systolic and diastolic phases by temporal parameters for healthy animals and an increase of the correlation significance in transition of the animal into the excited state. Based on the cardiovascular system response, the chief features of a shift of the functional crayfish state to pathological direction seem to include a stable heart rate reduction, a decrease of the heart contraction amplitude, a more frequent predominance of SD over DD, an increase of the means and the standard deviations of the parameters, especially of the cycle amplitudes. Changes of the sign and significance of correlation relations between inotropic and chronotropic parameters of cardiac activity in sick animals appear to indicate a disturbed mechanism of central coordination of the cardiovascular system work with its autonomic mechanisms. The results are discussed on the basis of known mechanisms of the heart activity control in Decapoda. The records of cardiac activity, such as laser light cardiograms (LLC), in testaceous invertebrates may be useful and interesting in studies on mechanisms and processes of internal control and management of the cardiovascular system activity of the animals.