The Lifecycle of the Orca

7

1750

At the beginning, the animals were referred to as killers of whale but later the name was changed to killer whales (King 4). We chose orcas because we wanted to learn more about their lifecycle considering that the animals are among the most highly socialized animals in the world. In addition, we wanted to find out how human activities threaten the life of the orcas particularly in the wild. This paper will discuss the biological lifecycle of orcas, how orcas interact with the environment and each other throughout their lifecycle, and how human beings affect the lifecycle of orcas. General Characteristics Orcas belong to the Kingdom Animalia, Class mammalian, order Cetacea, suborder Odoceti, Family Delphinidae, Genus Orcinus and Species orca (Northwest Regional Office [NRO]). They are well adapted to live in various environments and so they inhabit all oceans though they have a preference for cooler regions and coastal regions. They are highly social where they live in form of family groups that are known as pods with each pod consisting of 3 to 25 orcas (NRO). In addition, orcas hunt in groups and in a coordinated manner that is considered similar to the wolves. The family groups usually trace their origin to the mother’s side which means that they are matrilineal. Orcas are distinctively colored with patches of black and white which is an adaptation feature that makes it a deadly predator as the coloring makes it hard for preys to consider it dangerous (NRO). When it comes to size and weight, orcas can be as long as 10 meters and can weigh as heavy as 8164 kilograms (NRO). The senses of orcas are well developed with each pod having its distinct sound which is passed from generation to generation and it is believed to be a manifestation of culture (Ivkovich et al. n.pag.). Their diet is usually very varied and it consists of squids, penguins, sea lions, dolphins, whales, and tortoises (NRO). Literature Review Biological Lifecycle Reproduction and Mating Most of the information that is known about the reproduction of orcas has been gathered from studies carried out in zoological parks where the animals are kept in captivity. Sea World has the largest collection of orcas. From the observations carried out there, it has been found out that the female orcas reach sexual maturity at the age of 6 to 10 years while the male orcas reach sexual maturity at the age of 10 to 13 years (Sea World). Female orcas are usually on heat several times in a year which means that they are polyestrous and they ovulate even in the absence of a male counterpart a characteristic that is very rare in mammals (Boran, Heimlich and Boran 28). Another thing is that the female orcas do not experience menstrual blood loss (Sea World). Both the male and female orcas are promiscuous where they mate with more than one partner (Sea World). It is important to note that the age at which mating starts varies depending on the situation where in captivity orcas start mating early but in the wild mating takes time to occur and this has been associated with a rigid social structure where the males have to wait until they are socially mature before they can start mating (Boran, Heimlich and Boran 28). It is believed that mating does not occur between members of the same pod as a way of avoiding incest (Boran, Heimlich and Boran 31). Birth and Care of the Young Ones Gestation takes approximately 15 to 18 months after which a single calf is born. Most of the time the calves are born tail first but in some rare occasions calves have been born head first. Female orcas can bear approximately five calves within a period of 25 years (Boran, Heimlich