Senses

Killer Whales

Senses

Hearing

  1. Killer whales have a well-developed, acute sense of hearing.
  2. Hearing range.
    • Early studies suggested that the hearing range of killer whales was about 0.5 to 31 kHz. More recent studies on younger whales discovered that the whales could hear sounds at frequencies as high as 100 kHz. Greatest sensitivity is at about 15 kHz.
  3. Mechanics of sound reception.
    • A toothed whale's small external ear openings don't seem to be important in conducting sound. They lead to reduced ear canals that are not connected to the middle ears.
    • Soft tissue and bone conduct sound to a toothed whale's middle and inner ears. In particular, fat lobes in a toothed whale's lower jaw appear to be an adaptation for conveying sound to the ears.
    • In toothed whales, ears aren't attached to the skull. Ligaments hold each ear in a foam-filled cavity outside the skull. This separation of the ears allows a killer whale to localize sound, which is important for echolocation. (See Communication & Echolocation.)

Eyesight

  1. Killer whales have acute vision both in and out of the water.
  2. The eyes are located in front of and below the eye spot.

  3. The lens of a marine mammal's eye is stronger than that of a land mammal.
    • In the eye of a land mammal, the cornea focuses light rays toward the lens, which further focuses the light rays onto the retina. Underwater, the cornea isn't able to adequately focus waves into the lens because the refractive index of water is similar to that of the interior of the eye.
    • The eye of a marine mammal compensates for this lack of refraction at the cornea interface by having a much stronger, spherical lens. It is more similar to the lens of a fish's eye than the lens of a land mammal's eye.
    • In air, a marine mammal's eye compensates for the added refraction at the air-cornea interface. At least in bright light, constricting the pupil helps, but it doesn't fully explain how a whale achieves visual acuity in air. Research is ongoing.
  4. DNA from several other species of toothed whales indicated that the eyes of these whales do not develop pigment cells called "S-cones," which are sensitive to blue light. Researchers theorize that all modern cetaceans, including killer whales, lack these visual pigments and therefore aren't able to discriminate color in the blue wavelengths.
  5. In studies at SeaWorld, killer whales visually discriminated among similar objects. During more than one hundred trials a killer whale was shown an object and cued to find a matching object. When given two choices, the whale chose the matching object with 92% accuracy, and when three choices were presented the whale's accuracy was about 82%. Researchers did not determine whether the whale was responding to shape, size, or color. Future studies may provide more detailed information on the visual abilities of killer whale.
  6. In the often darkened waters of the ocean, eyesight may be of little help in locating prey. Under these conditions, killer whales probably rely on sound production and reception to navigate and find prey in murky waters.

Tactile

  1. Anatomical studies and observations of behavior indicate that a killer whale's sense of touch is well developed. Studies of closely related species (common dolphins, bottlenose dolphins, and false killer whales) suggest that the most sensitive areas are the blowhole region and areas around the eyes and mouth.
  2. Killer whales are very sensitive to touch.

Taste

  1. Little is known about a killer whale's sense of taste. They do have taste buds, although they haven't been well studied. In zoological parks, killer whales show strong preferences for specific food fishes.
  2. In zoological parks, killer whales show strong
    preferences for specific types of fish.

Smell

  1. Olfactory lobes of the brain and olfactory nerves are absent in all toothed whales, indicating that they have no sense of smell. Being air-breathing mammals that spend a majority of time under water, a sense of smell would go largely unused in killer whales.