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Killer Whale Biology

Killer whales- Scientifically Speaking!

Killer whales are fascinating marine mammals. The more we learn about them, the more questions arise.  So what have scientists found out so far?

Killer whales are the largest member of the dolphin family, Delphinidae.  They can be found in oceans around the world.  Presently, a single species is recognized, Orcinus orca. 

 

Scientific Classification

Scientific Name
 Orcinus orca
KingdomAnimaliaAll animals
PhylumChordataAnimals with a developed notochord
SubphylumVertebrataAnimals with a backbone
ClassMammaliaEndothermic ('warmblooded') animals that bear live young and have mammary glands
OrderCetaceaAll whales, dolphins, and porpoises
Suborder  
OdontocetiAll toothed whales
Family
Delphinidae
All oceanic dolphins
Genus   Orcinus
Species     Orca


Life History

Killer whales are long-lived animals.  Mean life expectancy (at 0.5 years) for females is 46 years and they have a  maximum life expectancy of about 80 years. Males have a mean life expectancy of 31 years, with maximum longevities of 60-70 years. Mortality is highest in very young animals (within the first year) and very old animals. 

Killer whales have few young, but very high maternal investment in calves.  Females give birth for the first time at approximately 14 years of age. Gestation lasts approximately 16-17 months, with a single calf being born.  Females are able to bear young until about 40 years of age. Killer whale calves will nurse for at least one year, if not more.  For resident killer whales, neither female nor male offspring disperse from their mother.   


Males vs. Females

Killer whales are sexually dimorphic, meaning the males and females look different at maturity.  Males may reach up to 9.0 m, and 5,568 kg , while females are smaller at 7.7 m and 4,000 kg (Dahlheim and Heyning 1999).

 

 

 

 

Male killer whales start to 'sprout' a tall, triangular dorsal fin in their teen years. At maturity, this fin can be as high as 1.8 m.

 

 

 

 

Females retain a smaller, more curved dorsal fin throughout their lives.

 

 

 

Adult males have much larger pectoral fins than females and the tips of their tail flukes curve downwards.  These features likely help stabilize the female during mating.

 

 

Male and female killer whales also have different markings on their underside.


Female                         Male