Orca Killer Whales
Orcas measure 27-33 feet and weigh between 8,000-13,000 pounds. Orca’s have jet-black bodies with white patches above the eyes, under the jaw and on the belly, extending to their sides. Behind and below the dorsal fin is a gray "saddle patch" that is often scratched and marked. Like human fingerprints, each whale’s unique saddle patch markings, coupled with the shape of its dorsal fin, allows positive identification of the individual. Orcas are the biggest member of the dolphin (Delphinidae) family.
- Orcas’ teeth, numbering about 45 and each measuring about 3 inches (7.6 centimeters) long, are shaped for ripping and tearing prey. Orcas do not chew their food. They can swallow small seals and sea lions whole - the prey just slides down the orcas’ large throats!
- Often referred to as "wolves of the sea," orcas live and hunt together in cooperative pods, or family groups, much like a pack of wolves. They work together as they hunt.
- Animals looking down on an orca from above, such as a seal on an ice floe, might not see it because the whale’s dark back blends with the water below. On the other hand, the whale’s white underside blends with the light streaming down into the sea from the surface, making it hard to spot from below.
- The orca diet consists of fish, squid, seals, sea lions, penguins, dolphins, porpoises and large whales like the blue whale. Some orcas have been known to slide on to beaches in order to capture a good meal.
- Orcas have no natural predators and can live to about 50-80 years old. Humans have hunted orcas but not often because it takes 21 orcas to produce the same amount of oil as one sperm whale.
- Orcas live in three basic social structures (types of pods). "Resident orcas" (possessing lifelong family bonds, living in large matrilineal groups, feeding mainly on fish, vocalizing in highly variable, complex "dialects"); "transients" (possessing more fluid, less persistent family bonds, living in smaller groups, feeding mainly on other marine mammals, vocalizing in less variable, less complex dialects); and "offshores" about which little is known.
- Orcas are able to reach a speed of about 30 miles (48 kilometers) an hour. The record for an orca is 34.5 miles an hour.
- Different orca pods "sound" different. Each pod has their own dialect of sounds. They can easily recognize their own pod from several miles away based on the differences in calls.
- Worldwide population of killer whales is unknown. Population estimates in the Antarctic range from 70,000 to 180,000.
Behaviors: The killer whale is also known as the blackfish, grampus, orca and because large males have a tall dorsal fin, the sword fish. They have been known to attack and mortally wound baleen whales, and then leave without eating them. The only other mammals known to have true dialects are humans, some monkeys and the sperm whale.
Voice: Whistles, squeaks and whines – pods have a similar set of calls or "dialect"
Diet: Fishes, squids, sea turtles, sea birds, porpoises and seals
Habitat Type: Upper layers of cooler coastal seas; occasionally large rivers and tropical seas
Range: In Atlantic from pack ice to Lesser Antilles, including the Gulf of Mexico. In Pacific from Chukchi Sea to the equator.
Culture: Killer whales are complex social predators, with life history parameters and a pattern of cognitive development similar to humans. They have an advanced central nervous and sensory system, an extended juvenile developmental period, and a complex learned communication system. Different groups will develop their own cultures.
Breeding: Gestation in killer whales is approximately seventeen months and, once born, a whale takes over a decade to reach sexual maturity. Breeding apparently does not occur within pods, but between whales from distantly related pods. A number of associating and potentially interbreeding pods may form a "population," the largest social division. A population can number in the hundreds and can be separated from other populations on the basis of genetic or acoustic analysis and association patterns.
Hunting: In Prince William Sound, killer whales feed primarily on Dall’s porpoise and harbor seals. When hunting seals, the whales separate and slide along shorelines or through tight, rock-strewn channels. They also forage near tidewater glaciers in search of seals that haul out on the ice floes in late spring. In open water, where Dall’s porpoise are found, the whales of this region spread out across a passage, breathing quietly, milling at the surface, silently awaiting prey. The whales of this region do not eat fish.
Tossing Sting Rays: Killer whales off New Zealand toss venomous stingrays back and forth with their teeth. As reported in the New Scientist, a whale will pluck a ray off the ocean floor. When the whale resurfaces, the ray is still alive, flapping in the whale’s mouth. What happens next can best be described as a marine version of a game of frisbee: one whale tosses the ray to a second, which then either tosses the ray back or forwards it to a third. Researchers believe the action is an attempt to position the ray so that it can be eaten safely. Another possibility is that tossing stingrays is one way adult killer whales teach their offspring to catch dangerous prey.
The whales in our waters
The striking black and white markings of killer whales can bring small boats and whale-watching vessels flocking and make B.C. Ferries passengers run for the rail.
The best known whales around Vancouver Island are the salmon-eating resident killer whales.
Endangered southern residents have 88 members in three pods — 43 in L Pod (not including Lolita, an L Pod whale who has been at Miami Seaquarium since her capture in 1972), 26 in J Pod and 19 in K Pod.
Threatened northern residents have 230 whales in 16 pods, not including Corky who was captured in 1969 and is at Sea World in California.
Major threats to resident orcas are environmental contamination, dwindling supplies of salmon and noise.
Transient killer whales, which eat marine mammals, number about 220 and are also federally designated as threatened. Transients often travel alone, but do band together only to hunt.
In the late 1980s, scientists discovered a population of offshore orcas, which may be the ancestors of the northern and southern residents.
Although little is known about them, more than 250 have been identified and it is believed the number could be considerably higher. They are designated as being of special concern.
Offshores travel in large groups and are believed to be fish-eating.
Southern residents are commonly seen in Juan de Fuca Strait, Haro Strait around the San Juan Islands and along the west coast of Vancouver Island, Washington and Oregon from April to November. J Pod often stays around for the winter.
In winter, southern residents have been reported as far south as Monterey Bay in California and as far north as the Queen Charlotte Islands. Otherwise, little is known about their winter movements.
Northern residents spend much of the summer and fall around Campbell River, Alberni Inlet, Johnstone Strait, up to Dixon Entrance and into southern Queen Charlotte Strait. However, they have been seen as far south as Grays Harbor, Washington and as far north as Glacier Bay, Alaska.
Little is known about their winter and spring movements, but they may spend time in the deep water past the continental shelf.
Transients are found on the coast year round, but their movements are unpredictable. Transients can range up to 1,500 kilometres along the coast from Alaska to California. These killer whales spend most of their time in
open waters and do not usually come close to shore.
Killer whales, which grow to about nine metres in length, and are really a large dolphin, are found in every ocean, but it is not known how many exist worldwide.
Times Colonist February 10, 2008
© 2007 Times Colonist