EFFECTS OF PRESSURE AND TEMPERATURE ON THE EKG AND HEART RATE OF THE HYDROTHERMAL VENT CRAB<i>BYTHOGRAEA THERMYDRON</i>(BRACHYURA)

Abstract

Effects of pressure and temperature on the electrocardiogram (EKG) and heart rate of crabs from the Galapagos deep-sea (2500 meters) hydrothermal vents were studied. Vent crabs require high hydrostatic pressure for long term survival. During decompression their EKG is disrupted and their heart rate is reduced. Low temperature reduces these decompression effects. The crabs have a higher temperature tolerance while at their environmental pressure (238 atm) and can withstand short-term exposure to temperatures as high as 37°C. Possible mechanisms for the action of pressure on neuromuscular systems are discussed. Habits and physiological capabilities of the crabs in the unusual vent environment are suggested on the basis of their physiological tolerances.