Thermal preference, tolerance and temperature-dependent respiration in the California sea hare Aplysia californica

The thermoregulatory behavior of sea hare Aplysia californica was determined in a horizontal thermal gradient; with a preferred temperature (PT) of 18.3 degree C for the day cycle and 20.8 degree C for the night cycle. The displacement velocity demonstrated an initial rate of 30 cm.h super( -1) and gradually the velocity diminished to 18 cm.h super( -1) with several fluctuations mainly at 02:00 am. Critical Temperature Maxima (CTMax refers to the temperature point where at least 50% of the experimental group have a loss of attachment) was measured at three acclimation temperatures (16 degree C, 19 degree C and 22 degree C). At the lowest acclimation temperature (16 degree C), 50% of the experimental group had an attachment loss at CTMax 32.7 degree C, and in a higher acclimation temperature (22 degree C) CTMax was 36.2 degree C. The Oxygen Consumption Rate (OCR) was closely correlated to acclimation temperature, and at 16 degree C and 19 degree C sea hare had a relatively stable metabolic rate, with OCR increasing to 9 mg O sub( 2) h super( -1).kg super( -1) w.w. in a higher acclimation temperature.