The killer whale is the marine omnipresent mammal. They are the generalized species feeding on varied food source available. They are considered among the highly social animals. The killer whale is highly praised for the sophisticated hunting techniques and peculiar means of communication by means of vocalization (1). There are five types of the killer whale (2). Among the marine animals, the killer whale has the second heaviest brain indicating the high intelligence.
The most astonishing phenomenon killer whale undergoes is the Menopause. Menopause is the condition marked by the stoppage of the reproduction. This is considering the biologically rare phenomenon. Very few species in the earth shows this phenomenon two species of the whale and human only shows this phenomenon.
The length of the killer whales varies up to 8 meters in length. The Male is longer than female.
The weight of the female can grow up to 6 tons and the male can be up to 10 tons.
3. The speed of the Killer Whale
Due to the robust body, the killer whale has the astonishing speed of 56 kilometer in one hour.
4. Life Span
The lifespan of the killer whale varies from the wild and captive varieties. Generally, the lifespan of the captive female is estimated to less than 40 years whereas in wild it has been observed to have the lifespan up to 105 years.
5. Gestation Period
The gestation period varies from 15 to 18 months. Female give one offspring once every five years.
6. Possible Cause of Menopause
Various researchers around the globe have indicated the possible cause of menopause in Killer whale. Some of them are summarized below:
1. Survival Ratio
The reproduction of killer whale takes place at the age of 15 and stops at the age of 30s and 40s. In killer whale, the offspring from the older mother has lower survival ratio than with the younger mother.
2. Grandmother Hypothesis
This hypothesis claims that the after the menopause the female can take care of the grandchildren which drastically increases the survival of children. The grandchildren being the carrier of the own gene helps in the gene spread. There is the strong argument against this tenet that grandchild carrying less than one-third of the gene cannot be efficient to pass the gene instead of own offspring.
There is the estimation that killer whale can invest more time and resource in finding the food instead of raising the offspring. This drastically increases the survival of the Matriarchal group.
1. Rendell, Luke; Hal Whitehead (2001). "Culture in whales and dolphins". Behavioral and Brain Sciences. 24 (2): 299–333. Retrieved on 3 January 2017.
2. Pitman, et al. (2003). "Three forms of killer whales (Orcinus orca) in Antarctic waters" (PDF). Journal of Cetacean Research and Management. 5 (2): 131–139.