Physical Characteristics

Killer Whales

Physical Characteristics

Size

  1. Killer whale sizes vary significantly between different geographical areas.
  2. Adult male killer whales are larger than adult females. Data from Icelandic killer whales indicate that an average-size male is about 5.8 to 6.7 m (19–22 ft.) long. At SeaWorld, average size for adult males is 6.6 m (21.7 ft.). Two adult male killer whales at SeaWorld weigh 4,340 kg (9,570 lb.) and 5,380 kg (11,860 lb.)
  3. Male.
    The largest male killer whale ever recorded was 9.8 m (32 ft.).

    Female.
    The largest female killer whale ever recorded was 8.5 m (28 ft.).

    That's over twice the size of a Shamu Cruiser at 4.4 m (14 ft. 7 in.).

  4. Data from Icelandic killer whales indicate that an average-size female killer whale is 4.9 to 5.8 m (16–19 ft.). At SeaWorld, average size for females is 5.5 m (18 ft.) and 2,442 kg. (5,384 lb.). SeaWorld’s adult female whales range in weight from 2,313 kg (5,100 lb.) to 3,719 kg (8,200 lb.)
  5. The largest male ever recorded was 9.8 m (32 ft.) and weighed 10,000 kg (22,000 lb.). The largest female recorded was 8.5 m (28 ft.) and weighed 7,500 kg (16,500 lb.).

Body Shape

  1. The general body shape of a killer whale is roughly cylindrical but tapering at both ends. This characteristic fusiform shape is quite energy efficient for swimming. Compared to other body shapes, this body shape creates less drag (the opposing force an object generates as it travels through water).

Coloration

  1. Killer whales are solid black and white, with a gray patch called a “saddle” or a “cape” on the back, just behind the dorsal fin.
  2. The dorsal surfaces are predominantly black with the exception
    of a gray "saddle" located behind the dorsal fin.

  3. The large areas of black and white are distinctly separate.
    • The entire dorsal (top) surface and pectoral flippers are black except for the gray saddle.
    • The ventral (bottom) surface, lower jaw, and undersides of the tail flukes are mostly white. The undersides of the tail flukes are fringed with black.
    • An oval, white "eyespot" is just above and slightly behind each eye.
  4. The size and shape of killer whale’s white areas and gray saddle vary among regional populations.
  5. The distinctive coloration of killer whales is a type of disruptive coloration, a pattern that obscures the outline of an animal by contradicting the animal’s body shape. In the flickering, filtered sunlight of the sea, other animals may not recognize a killer whale as a potential predator.
  6. Killer whales are countershaded: the dorsal (top) surface is darker than the ventral (underneath) surface. When lighting is from above, a countershaded animal appears inconspicuous.
  7. The white eyespot is part of a killer whale's disruptive coloration.

  8. Albinism in killer whales has been reported 74 times in a 36-year period, and as recently as 1970 an all-white killer whale calf was studied in British Columbia.
  9. The demarcation between black and white colors
    is pronounced on the ventral side.

Pectoral Flippers

  1. A killer whale's forelimbs are adapted for swimming. A killer whales uses its rounded, paddlelike pectoral flippers to steer and, with the help of the flukes, to stop.
  2. Pectoral flippers have the major skeletal elements of the forelimbs of land mammals, but they are shortened and modified. The skeletal elements are rigidly supported by connective tissue.
  3. A killer whale's pectoral flipper contains five digits much like the fingers on a human hand.

  4. Blood circulation in the pectoral flippers adjusts to help maintain body temperature. See Thermoregulation.
  5. The pectoral flippers of male killer whales are proportionately larger than those of females. A large male killer whale may have pectoral flippers as large as 2 m (6.5 ft.) long and 1.2 m (4 ft.) wide. A female's pectoral flippers are significantly smaller.

Flukes

  1. Each lobe of the two-lobed tail is called a fluke. Flukes are flat pads of tough, dense, fibrous connective tissue, completely without bone or cartilage.
  2. Flukes are flattened pads of tough, dense, connective
    tissue with no bones.

  3. Although killer whales have 50 to 54 vertebrae, no bones extend into the flukes. Without bones or even cartilage in the flukes, it is not unusual to see them curved, especially in larger males.
  4. A large male killer whale may have tail flukes measuring 2.7 m (9 ft.) from tip to tip.
  5. Longitudinal muscles in the back one-third of the body (both above and below the spine) move the flukes up and down.
  6. Like the arteries of the flippers, the arteries of the flukes are surrounded by veins to help maintain body temperature. See Thermoregulation.

Dorsal Fin

  1. Like the flukes, the dorsal fin is made of dense, fibrous connective tissue, without bones or cartilage.
  2. Killer whale dorsal fins are the tallest of any cetacean.

  3. The dorsal fin of a male killer whale is proportionately larger than that of a female.
    • In adult males, the dorsal fin is tall and triangular. Reaching a height of up to 1.8 m (6 ft.) in a large adult male, it is the tallest dorsal fin of all cetaceans. In most females, the dorsal fin is slightly falcate (backward-curving) and smaller - about 0.9 to 1.2 m (3-4 ft.) tall.
  4. As in the flukes and the flippers, arteries in the dorsal fin are surrounded by veins to help maintain body temperature. See Thermoregulation.
  5. Like the keel of a boat, the dorsal fin may help stabilize a killer whale as it swims at high speeds, but a fin is not essential to a whale's balance.
  6. No one is exactly sure why the dorsal fins of killer whales bend, but it may have to do with genetics, injuries, or because the fins can be taller than many humans without any hard bones or muscles for support.
  7. Some killer whales (both male and female) have irregular-shaped dorsal fins: they may be curved, wavy, twisted, scarred, or bent. Of the 30 adult male killer whales that have been photo-identified in New Zealand waters, seven have collapsing or bent dorsal fins.

Head

  1. A killer whale has an indistinct rostrum (snoutlike projection).
  2. A killer whale's eyes are on each side of its head, just behind and above the corner of its mouth, and in front of its white eyespot.
    • A killer whale's eyes are about the same size as the eyes of a cow.
    • Glands at the inner corners of the eye sockets secrete an oily, jellylike mucus that lubricates the eyes, washes away debris, and probably helps streamline the eyes as a killer whale swims. This tearlike film may also protect the eyes from infective organisms.
  3. Ears are small inconspicuous openings just behind each eye, with no external flaps or pinnae.
  4. A single blowhole on top of the head is covered by a muscular flap.
    • A killer whale breathes through its blowhole.
    • The blowhole is relaxed in a closed position, and the flap provides a water-tight seal. To open its blowhole, a killer whale contracts the muscular flap.
  5. A killer whale's large teeth are conical and interlocking.
    • A killer whale's teeth grasp and tear food. They don't chew.
    • The number of teeth varies among individuals. There are usually 10 to 14 teeth on each side of each jaw (40–56 teeth total).
    • Teeth are about 7.6 cm (3 in.) long and about 2.5 cm (1 in.) in diameter.
    • A killer whale's upper teeth erupt at about two to three months. The lower teeth emerge at about four months.

Skin

  1. A killer whale's black and white skin is smooth. The outer layer continually and rapidly renews itself, and the old skin sloughs off.

Regional Differences in Physical Appearance

  1. The three forms of Antarctic killer whales look different and are easy to tell apart.
    • "Type A" killer whales have a medium-size, horizontal eyepatch and lack a dorsal saddle.
    • "Type B" killer whales have a horizontal eyepatch that’s twice the size as that of the “type A” whales. They have a dorsal saddle.
    • "Type C" killer whales have a small, forward-slanting eyepatch and a dorsal saddle.
  2. Experts note subtle differences between the resident and transient killer whales of the eastern North Pacific Ocean.
    • In general, resident killer whales have a rounded tip on the dorsal fin, and the fin tip tends to be positioned over the rear of the fin base. The dorsal saddle may contain some black areas.
    • Transient killer whales tend to have a more pointed dorsal fin, and the tip is positioned over the middle of the fin base. The dorsal saddle does not contain any black areas.

Photo-Identification of Individual Whales

  1. Researchers in the eastern North Pacific and in New Zealand have learned to recognize some individual killer whales from photographs, especially photos of the dorsal fin and saddle patch.
    • Researchers photograph the dorsal fin when the whale rises out of the water to breathe. This action exposes the most markings on the back and dorsal fin. Studying the photos, these researchers recognize subtle differences in whales’ body appearance.
    • Researchers identify individuals using many features including dorsal fin shape and relative size, pigmentation patterns, scars, deformities, detail of tail fluke edges, encrustations, blemishes, and bite marks.
  2. Photo-identification is an important research tool for studying various aspects of cetacean biology, including movements, reproduction, behavior, and population dynamics. Photo-identification helps document the lives of individual whales in considerable detail.
  3. More than 1,300 individual whales have been identified in this manner. (Using NOAA SARs = 1,369, which does not include "unclassified" individuals or individuals identified in other areas outside of the U.S.)