Comp. Biochem. Physiol. Vol. 88A, No. 2, pp. 201-206, 1987

ADRIAN HAILEY and GEORGE THEOPHILIDIS

Laboratory of Animal Physiology, University of Thessaloniki, Thessaloniki, Greece 54006

(Received 15 January 1987)

Abstract-1. Heart rate (HR) was measured during and after stress and activity in the armoured legless lizard Ophisaurus apodus, the snake Natrix natrix and the tortoise Testudo hermanni, at different body temperatures T_b. These are discussed in relation to field T_b, defensive behaviour and published VO₂.

2. Ophisaurus apodus used passive defence, including hemipenis or cloacal sac eversion and prolonged immobility after release. This was correlated with a low degree of tachycardia, bradycardia at low T_b, low metabolism and armour.

3. Defence behaviour was T_b-dependent in wild T. hermanni, with passive withdrawal into the shell at low T_b and active struggling at high T_b. The degree of tachycardia was lower at low T_b.

4. Standard and active oxygen pulse OP were insensitive to T_b in O. apodus and N. natrix, and their SOP was lower than tetrapod lizards. Factorial scope of HR was reduced at 35^oC, just above the activity T_b range of these species.

5. Recovery of HR after activity in T. hermanni was much more rapid than in the squamates, and of similar duration to recovery after stress. It is suggested that tortoises do not utilize anaerobic metabolism during activity.