IKAN Guide to Whales

Orca (Killer whale) - Orcinus orca

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orca

An adult can grow to 9.8 meters and weigh up to 9 tonnes. Newborn calves can measure up to 2.5 meters in length and weigh around 180 kg.

The killer whale, also known as the orca, is the largest member to the Delphinae Family.

Orcas are distributed on a worldwide basis and can be found in all waters inhabiting both offshore and inshore areas which testifies to their remarkable adaptation. However, like other top predators, the numbers of orcas are not abundant in the world. More over, thought dangerous, orcas were killed as people thought that they were blood-thirsty and violent animals. However, when research started in 1970 studies showed that orcas are both inquisitive and friendly and do not attack humans. There are three forms of orcas: Resident orcas, transient orcas and off shore orcas. These three are diffirent in most aspects of their behavior ,social organization and ecology. An easily observable diffirence is their diet. Residents and offshores eat mainly fish but transients eat marine mammals such as sea lion, dolphins and even great whales. Orcas also form tightly knit pods that consist of family groups. These groups are organized along lines of maternal lineage. The bonds among females and their offsprings are very strong, and they spend entire their life together. Orcas have been the victim of hunting and continue to be the victim of habitat destruction as well as pollution. Presently there is no study about the ecology of orcas around Japanese coastal waters. Between 1950 and 1970, more than 1000 animals were killed by small type coastal whaling. It is presumed that the resident orcas were killed during this period and only transient orcas intermittently pass through coastal waters. The population estimate is infered from the population of short-finned pilot whale as these two whales have similar ecology. The fisheries Agency lists orcas as rare.