The killer whales’ temperature is 36.4°c, which is 97.5°F.

As the animal generally moves in cold waters, there are a lot of heat losses. To avoid heat deficiency, the animal uses several means:

• ISOLATION, (lard layer).
• INCREASE METABOLISM.
• REDUCTION IN THE UNDER EPIDERMIC BLOOD FLUX.

On the body, the lard layer is very thick. On the fins however this layer is thinner. Therefore it is there that the thermoregulation will happen (thermal exchange principle), as well as with the arteries and veins system (vasoconstriction and vasodilatation).

The orca’s body temperature increases when it hunts; it swims quickly or stays a long time on the surface (warmer outside environment). So it will have to eliminate this additional heat. In order to do so, the killer whale is going to dilate its arteries (1) (containing the warm blood) at the pectoral and dorsal fins level. It’s the VASODILATATION principle. The fat layer being thinner in this area, the heat coming from the arteries will disperse more easily in the marine environment. The body is going to become cooler. The veins (2) are going to send back a cooler blood to the central nucleus. The cooling effect is accentuated. At the core of the organism, the arteries’ diameter is smaller in order to limit the heat dissipation (it will be sent to the outside not the inside). It is the VASOCONSTRICTION. Hence the maximum heat is conveyed to the fins where the thermal exchange is easier and so until the body temperature has reached its normal level.

However, the killer whales are often in cold water and must, more often, keep the heat in than lose it out. In some instance, the thick layer of fat is not enough to keep warm. That’s the reason why we find an AGAINST THE FLOW BLOOD CIRCULATON system in the fins. In fact, veins (2) (poorer blood, cool.) are coiled up around the arteries (1) (new blood, warm). To maintain the body heat, during dives for example, the orca is going to reduce the arteries diameter in its fins (VASOCONSTRICTION) so as to limit the outside exchanges. Furthermore, some of the heat will be transferred from the arteries to the veins (very close and carrying the blood to the central nucleus). The heat is then kept within the body and not dispersed to the outside. There is also a limitation of calorific losses.

If there is a need to increase the body temperature, the killer whale will increase its metabolism. Working out is the healthy option. The body temperature then arise…