The Orca is undoubtedly the top predator of the sea. Unlike other members of the dolphin family, which are uniquely adapted to local conditions and diet, the Orca can be found in all oceans of the world. Its strength and ability to hunt cooperatively enable it to eat anything in the ocean, from the smallest fish to the largest animals in the world, the baleen whales. The Orca's success is due to two differentiating factors: its extraordinary adaptation to the sea, and its remarkable social system.
As a toothed whale, orcas have a single blowhole and powerful upper and lower jaws that are lined on each side with sharp teeth. Their teeth are curved slightly inward to allow them to capture live marine prey.
Orcas generally take 4 short breaths 10 to 30 seconds apart and then dive for between 1 and 4 minutes. Residents rarely dive for longer than 3 to 4 minutes, whereas transients can remain underwater for up to 15 minutes. Unlike humans, orcas do not breathe automatically. They must have conscious control, even when sleeping. While resting, all members of a pod take approximately the same number of breaths before diving. The blows of mother and calf are tightly linked and continue in respiratory synchrony throughout their lives.
Orca eyesight is equally effective in or out of the water. In fact, orcas are thought to use eyesight when 'spyhopping' above the surface of the water to spot boats, navigate by shoreline objects and even locate terrestrial prey such as sea lions. However, underwater visibility is often less than 50 meters and at night is negligible. Orcas have evolved to take advantage of the superiority of sound, which travels four times faster in water than in air and is equally effective day or night.
Orcas possess sophisticated underwater sonar that enables them to perceive their surroundings ten times more effectively than our most advanced equipment. Their nasal passages produce a series of extremely fast, high frequency sounds that bounce off objects and give important clues about their distance, speed, shape, texture and composition. Orcas are even able to 'zoom in' on objects by varying the pitch, loudness, duration, angle and breadth of this sonar and then use this information to navigate and to locate and chase prey. In addition, orcas use sound to communicate with each other and keep pods together. Different races and pods produce distinctively different acoustic signals.
Orcas are found in every ocean, from Arctic seas to tropical waters This is due more to their adaptive ability to prey on a wide variety of sea creatures than their anatomy, yet ingenious heat conserving mechanisms allow them such range. The Orca's circulatory system utilizes many arteries and veins in the flippers, flukes and dorsal fin that allow it to transfer heat from the body in warm conditions or conserve heat it as it swims in icy seas. Its sheer size also helps conserve heat as its surface area to volume ratio is lower than other mammals. A high metabolic rate increases heat production while a coating of blubber reduces heat loss, streamlines its body to conserve energy and serves as food storage.
Orcas exhibit dramatic coloring, with glossy black upper surfaces and brilliant white bellies. Strangely enough, by appearing lighter from below and darker from above this coloring allows the Orca to blend into the ocean environment and camouflage itself from prey. Color differences may also help orcas identify the opposite sex since females have an oval genital patch with three black spots and males have an elongated white patch with a single black slit covering the penis.
The Orca's skin is exquisitely sensitive to touch, and presumably plays an important role in maintaining social connectivity. In fact, trainers of captive orcas have found that touch is a more powerful motivator than food. Orcas are extremely sensual creatures and often engage in touching behavior. Mothers and calves frolic and caress each other regularly from birth, and adult males wrestle and roll with each other while displaying erections. In the 'greeting ceremonies' of the Pacific Northwest, members of two or more pods will swim tightly together and rub against each other's bodies for many hours. Such intimacy strengthens social bonds, and allows individual whales to benefit from the advantages of group life.
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