On testicular cooling in phocid seals

Abstract

Testicular and body core (intra-thoracic) temperatures were recorded in mature male harp seals (Pagophihs groenlandicuc) just prior to the mating season. In phocid seals the testicles are outside the abdomen but protected under 7-8 cm of insulating skin and blubber. The temperature of the testicles was found to be 14°C lower than body core temperature. Inspection of the veins of the pelvic and hind-flipper reglon of a male ribbon seal (Histrrophocafaciata) revealed that the testicles of phocid seals are enveloped in venous plexuses communicating with the veins of the hind flippers. It is suggested that cooling of the paraabdominal testicles of phocid seals is attained by passage of cold blood from the hind flippers through thc extra-testicular plexuses.