Orca thermal windows are a very important means of regulating core body temperature and today we had a fantastic view of these dorsal fins and flukes as Lucky and her Pod were successful on an early morning hunt. A rather beautiful morning welcomed us into The Patch as all eyes scanned for the Orca with blows and dorsal fins sighted just ahead. Stealthy, we watched on as the movements of each pod member looked serious before they increased energy levels dramatically. The surge was on as they raced and sent white water flying with all members of the family working hard to get close to the morning meal. The kill was made at depth and apart from a light oil slick forming and plume of blood settling midwater below us it was not clear to see exactly what they had captured. Females were carrying with them chunks of white and grey flesh but soon the meal was consumed and breakfast must have only been on the smaller side for the Orca. The family began to regroup as the impressive males of the pod surfaced and showed off their enormous dorsal fins which soon had us talking about thermal windows.
Orca are well insulted thanks to their thick blubber but when it comes to cooling off especially after a fast pace surge like this morning their fins become very useful for more than just stability. The dorsal fin, pectoral fins and fluke have blood vessels positioned much closer together and without thick blubber on these areas they create what is known as a thermal window. Warm blood from the heart is pumped to the extremities and as the warm blood moves to the dorsal fin it goes through a process known as counter-current heat exchange. Warm blood pumped through an artery is located adjacent to the veins returning from that cool extremity. The warm arterial blood transfers its heat by simple conduction to the adjacent cool venous blood to ensure the blood returning back to the heart is warm and avoids any shock to the heart. It is an incredible process and these thermal windows ensure our Orca maintain a steady core body temperature of 37 degrees. It makes us wonder how Lucky controls her temperature with most of her dorsal fin missing and if she heats up quicker or takes longer to cool off than her other pod embers. Thankfully, she is a picture of health and doing well so managing her thermal windows doesn’t seem to be an issue for her. It was fantastic to spend some time with Lucky today and catchup with members of her family we have not seen or spent time with for a while as generally they hunt outside of The Patch but not today, a successful kill in the hunting grounds for this lovely pod.
