It is increasing clear that marine mammals are able to live in their cold water environment because of their excellent insulation and consequent low heat loss. However, these adaptations for heat retention may become a disadvantage or problem in some circumstances such as during sustained or vigorous activity; in warm tropical waters; or in the very large whales with great volume to surface area ratios. Heat loss may also become altered during illness as in other mammals. Furthermore, attempts to quantify heat loss indicated a heat loss that was lower than expected considering their metabolic rate. It was the purpose of this study therefore to examine the whale's surface with infrared thermography to see if uneven or previously unrecognized areas of heat loss could be detected.

An infrared camera (AGA Thermovision) was used to examine surface heat loss of a healthy male killer whale (Orcinus orca) that was 6.6 m in length and weighed an estimated 3420 to 3696 kg.

There were several prominent areas of heat loss detected by this method. Both sides of the basal pectoral fin had enhanced heat loss relative to the rest of the fin (greater than 3°C difference) and these changed position on three separate days of observation. The fluke also showed areas of enhanced heat loss. The dorsal fin showed a homogeneous low heat loss, as did the majority of the body surface. Other isolated spots of greater than average heat loss included the melon, eye, two spots on the abdomen and an area surrounding the genital slit. In conclusion, there are many discrete spots on the killer whale that could contribute significantly to heat loss but because of their patchy distribution and changing locations with time, make quantification difficult. Also the pattern may be different in other cetaceans or in other circumstances. This technique may prove useful in detecting illness in marine mammals, since it is currently used to screen cattle for illness.