Adaptations for an Aquatic Environment
1. Swimming speed and duration are closely tied: high-speed swimming probably lasts only seconds while low-speed swimming may last for long periods of time.
2. Killer whales are among the fastest swimming marine mammals. They can swim at speeds up to 48.4 kph (30 mph), making them perhaps the second fastest marine mammal next to the Commerson's dolphin, which reaches swimming speeds up to 56 kph (35 mph). Killer whales generally cruise at much slower speeds, however, usually from 3.2 to 9.7 kph (2 - 6 mph).
3. Killer whales are very agile and maneuverable in the water.
4. When swimming near the surface, killer whales generally stay below water for 30 seconds or less.B. Diving.
1. When they dive, killer whales usually go to depths of about 30.5 to 61 m (100 - 200 ft.). Killer whales generally do not dive deep, although the deepest dive known under experimental conditions was 274.3 m (900 ft.).
2. When diving, killer whales may surface about every four to five minutes. At the surface they generally take two to five breaths at five to ten second intervals before another dive. They make approximately three to five short dives, each lasting 10 to 35 seconds. These are followed by longer dives lasting about one to four minutes.
3. Dives up to 10 minutes and longer have been seen, with the longest dive observed in the ocean lasting 12 minutes. Under experimental conditions, killer whales have made dives lasting as long as 15 minutes.
4. All marine mammals have special physiological adaptations when they dive. These adaptations enable a killer whale to conserve oxygen while under water.
5. A serious threat to human divers is decompression sickness or "the bends".
1. A killer whale breathes through a single blowhole on the dorsal surface of its head.(See Head.)
A killer whale breathes through a single blowhole. It inhales and closes the muscular flap before diving.
c. At the surface, the whale quickly inhales and closes its muscular flap covering its blowhole. The blowhole is relaxed in a closed position. To open the blowhole, a killer whale contracts the muscular flap.D. Thermoregulation.
1. Heat loss in water is about 27 times faster than in air at the same temperature.
2. Despite this rapid heat loss, killer whales are able to maintain a high body temperature that ranges from 36.4 C (97.5°F) to 38 C (100.4°F).
3. Killer whales have several adaptations to help them stay warm even in frigid water:
4. A killer whale's circulatory system adjusts to conserve or dissipate body heat and maintain body temperature.
A countercurrent heat exchange system in the flippers, flukes, and dorsal fin helps killer whales maintain body temperature.
b. This countercurrent heat exchange helps whales to conserve body heat. When a whale dives, blood is shunted away from the body surface. This decrease in circulation conserves body heat as well.
5. During prolonged exercise or in warm water, a killer whale may need to dissipate body heat. In this case, circulation increases to arteries near the surface of the flippers, flukes, and dorsal fin, and deceases to arteries providing blood to the body core. Excess heat is shed to the external environment.
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