Fun Facts
- Orcas are found in every ocean of the world.
- Scientists have identified three primary types of orca societies. They are described by the terms offshore, resident, and transient.
- Orcas reach sexual maturity at about the same age as humans.
- In the wild, orcas are thought to live to seventy or eighty years of age. There is some evidence that females live longer than males, and the average life expectancy of male orcas is around forty to fifty years.
- Orcas are voluntary breathers. For this reason, they sleep with only half of their brain at one time. The other half remains alert to regulate breathing. Resident whales typically remain near the surface, breathing and swimming in a pattern.
- When travelling together, resident pods have been observed to breathe in unison. Although it is not known why this occurs, it could be a way of helping the pod keep tabs on one another.
- Orcas are at the top of the food chain in the ocean. Transient orcas eat other marine mammals and have even been known to attack whales, including the enormous blue whale.
- The orca is the largest member of the dolphin family, and is not really a whale. Due to its size, however, the orca is frequently included in discussions of whales.
- Individual orcas can be identified by their dorsal fins and saddle patches. These characteristics are unique for each orca just as human fingerprints are all different. Vocalization characteristics are also unique for each individual.
Offshore
Little is known about offshore orcas. Orcas have been spotted far out to sea, beyond what is believed to be the range of even the transient whales which have
been identified. Due to the logistics of studying animals over such a vast area, very little research has been done on offshore orcas.
Resident
Resident whales are the most studied because, as the name suggests, they tend to
stay within a defined range. The pods are matriarchal in nature, and are generally comprised of several generations of females and their offspring. Although the huge males often take on the role of protector when the pod is threatened, they are protecting near-relatives (e.g. mothers, sisters, aunts) as opposed to a harem of cows.
Transient
Transient whales have also been identified off the coast of British Columbia. These whales tend to travel alone or in small groups of two and
three. As the
term transient implies, these whales do not stay within an easily-defined home range. Transients feed primarily on marine mammals. Perhaps due to their isolated nature, or perhaps because they do not want to advertise their presence to the seals, sea lions, and even other species of whales on which they prey, their vocalizations are much less frequent than those of their resident cousins.
Because of their far-ranging natures, these whales are much more difficult to study, and therefore, less is known abou their habits, social structures, and communications. Scientists believe that resident and transient whales do not interact. In fact, they believe that they are so genetically distinct that they would not mate.
Identification
By taking photographs of the dorsal fin, Dr. Bigg and his colleagues at the Pacific Biological Station in Nanaimo B.C. and at the Center for Whale Research
in Friday Harbour, Washington, were able to identify each individual orca. After compiling thousands of photographs of the orcas of British Columbia and Washington State, they were able to define the composition of the orca population. Each individual was assigned a number and as well an alphabetical letter which designated the individual's pod. This alpha-numerical system, and yearly photographic updates, has enabled researchers to keep track of pod members. 
Orcas are the largest member of the dolphin family, Delphinidae. Males grow to a maximum length of about 32ft (9.8m) and weight of 10 - 11 tons (9 - 10,000 kg) Females are smaller and grow to a maximum length of about 28ft ( 8.5m ), weighing as much as 7 -8 tons (6,500 to 7,500 kg). Calves at birth are about 8ft (2.4m) long and weigh about 400lbs (180 kg).
Orca bodies have distinctive black and white markings. Both females and males have similar markings except on the underside, where it is possible to
distinguish male from female. The dorsal fin also distinguishes male and female adults. In the mature male the erect dorsal fin may reach a height of 5 1/2 ft. (1.7m) but the female dorsal
fin grows only to an average of 3 ft. (0.9m)
Orcas are one of the toothed whales (Odontoceti), as are other dolphins and porpoises, pilot
whales and sperm whales etc. Orcas have 10 to 13 pairs of interlocking conical teeth in the upper and lower jaws, usually a total of 48. Sperm whales have teeth only in the lower jaw.
Orcas use their teeth primarily for grabbing prey. The number of rings within the teeth (anuili) may indicate how old an individual orca is, until about 30 years of age, when discrimination of new rings becomes difficult.
No one knows for sure how long an orca may live for, as the species has only been intensively observed since about 1970. However, studies show that for the Resident orcas along the Washington and B.C. coasts, females live an average of 50 years and may live as long as 80 years. It is not clear why, but males live significantly shorter lives, on average only about 30 years... and may reach a maximum age of 50 years. The oldest males in the Pacific Northwest study area are estimated to be just over forty years old. The mortality rate of newborn orcas is still unclear, but it is almost certainly quite high. Bigg et al estimated that it might be as high as 43% but did not have a lot of confidence in this number as the sample rate was so small. Largely, it was based on expected rates of reproduction and the pregnancy rate of large numbers of orcas killed by "small-type" whaling in the North Atlantic.
Copyright © 2003 Christina de Paula. All rights reserved.
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