The Killer Whale
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The Killer Whale
The killer whale (Orca) is the largest of ocean dolphins and is considered one of the most widely known types of whale. The killer whale is very recognizable, by its amazing color contrast of black and white and its tall dorsal fin. They are toothed whales with one blowhole and often the top predator in their respective ecosystem. The killer whale is perceived as a competitor for fish resources. There have been attempts by in Icelandic and Norwegian waters to remove this species for the purpose of fish resources. Fortunately the research interest of the killer whale is considerable. This interest has led to protection instead of destruction as a perceived competitor for fish resources. Public education is appropriate for the conservation of this type of species.
The killer whale can reach lengths of up to 31ft by males (although usually much smaller), and up to 27 feet by females. The body is very broad. The color is black with a large white area extending along the lower side from the chin to the anus. A distinctive large white spot is located just behind the eye. There is also a light saddle shaped area that’s grayish right behind the dorsal fin. When the killer whale is a calf, these colors are a yellowish tint. They become white as the whale matures. However there have been killer whales spotted that were entirely black or white. Male killer whales will weigh anywhere from 11000-14000lbs. The female is smaller weighing from 9000-10000 lbs. An accurate census of the Orca population is unknown. However, there are estimates for specific regions. For example, in the Antarctic, there is an estimated Orca population of 180,000 whales that is still growing.
The killer whales dorsal fin is the tallest of all whales. An adult male it can reach a height of 6ft, and its posterior region is nearly vertical. In females however the fin measures a height of up to 3ft. and the posterior region is concave. The flippers are very broad, rounded, and paddle shaped. It measures usually Ðј the length of the whale itself. The male’s flippers grow proportionately larger with age.
Killer whales are very well adapted for aquatic life. There coloration provides an excellent camouflage, looking down the black blends with dark water, and the light underside blends with the sky. Since heat is lost at a higher rate in water, than in air, the killer whale has thick blubber to maintain constant body temperature. Another way of maintaining constant body temperature is through their pectoral muscles, tail flukes, and dorsal fins. The arteries in them are surrounded with veins with cooled blood. These arteries transfer their warmth to the veins which in turn heat their body; this maintains a core temperature of 97.5 degrees Fahrenheit. While diving, the killer whale slows its heartbeat. By doing this they restrain the amount of blood that is circulating through their body. The blood is pushed to the lungs, brain, and heart rather than parts of the body that can tolerate low oxygen levels. This help the killer whale have longer deeper dives
Unlike the baleen whales, orcas are “toothed” whales, with true teeth rather than fibrous plates for filter-feeding. The teeth are very large and heavy and number from anywhere between 10-13 in each of the jaw bones. They are curved at the tip, point slightly inward, and interlock with those of the opposite jaw when the mouth is closed. They range in length from 4-5 inches. The killer whales teeth provide a firm basis for age determination. They do this by counting the layers of cementum in the teeth.
There are two types of killer whale. There are the residents, which habitually feed on fish, travel in very large groups, and are very vocal during foraging for food. There are also transients. They rely more heavily on marine mammals for food. The transient pods are much smaller than the residents, and are relatively quiet during foraging for food. The transients have been known to beach themselves temporarily in pursuit of seals, and attack large whales as a pack. The transients pick at their prey as a pack to wound it and slowly kill it.
The killer whale is the only whale that preys on warm blooded animals. A wide variety of animals are included in the killer whales diet. Their diet differs seasonally and regionally. They find food through echolocation. This is where they produce a noise, and wait for the echo to bounce back, helping them to locate their prey. There seems to be almost no marine organism that is safe from attack. They include available species of dolphins, sea lions, walruses, sea otters, sea birds, sea turtles, squid, shark, and even all large whales including the blue whale. Although there have been no documented instances of wild killer whales eating humans, a few unsuccessful attacks have been reported. They are known to at least eat 4-5% of their body weight daily. The types of prey it hunts however heavily rely on the ecosystem the whale habitats. The migration of these whales occur northward and southward with the seasons, following migration of their various sources of food.
The pod size can vary from anywhere between 75-100 animals. The larger pods are primarily resident pods and the smaller transient pods can range anywhere from 5-20 animals. Small pods contain at least one male killer whale, and larger pods contain 2-3. Through observational work, it is thought that killer whales remain with their pods throughout their entire life. The pods may however split when the death of the matriarch of the pod occurs. This allows the other daughters and their offspring to become more independent. Pods have their own distinctive calls, and pods that associate together share similar signals.
The male reaches sexual maturity between the ages of 10 and 16 years; the female usually matures two years earlier. Little is known about orcas breeding habits. Some sort of courtship behavior probably exists, and a single male most likely breeds with several females. Between December and February the males and females are believed to mate, and give birth to their young 11-12 months later. The newborns weigh anywhere from 300-400lbs Females breed once every 3-8 years. Male orcas have a life expectancy of 50-60 years. Females have a life expectancy of 90 years.
Killer whales were the second most frequently sighted cetacean species (after the minke whales) in the IDCR Antarctic whale sightings cruises conducted from 1979 through 1986. (Kasamatsu et al., 1988). Killer whales are generally widely distributed, occurring from among polar latitudes through equatorial regions. The limiting factors of the distribution are ice cover and shortage of prey. It is said however that they are most prominent within 800km of coast, but they can be encountered in all oceans mostly