Record Details

Bartholomew, George A;Lasiewski, R C
Heating and cooling rates, heart rate and simulated diving in the Galapagos marine iguana
Comparative Biochemistry and Physiology
Journal Article
Amblyrhynchus cristatus
1. During enforced submergences of 30–50 min, the animals remained quiet. Bradycardia developed slowly following submergence and conspicuous arrhythmia appeared. Bradycardia ended almost immediately following the termination of submergence.2. In both air and water the lizards heated approximately twice as rapidly as they cooled.3. Heart rate at any given body temperature was much slower during cooling than during heating, suggesting that circulatory adjustments are important in controlling rate of temperature change.4. Minimum heart rates in air increased with increasing temperature, and at all temperatures the smaller animal had a more rapid heart beat than the larger one.5. Ecological and comparative aspects of the responses of the marine iguana are discussed.