Born Free Foundation - Keep Wildlife in the Wild

The natural history of orca

The distinctive black and white orca or ‘killer whale’ is actually the largest member of the dolphin family and can be found in every ocean.  With their tall triangular dorsal (back) fin, orca are enormous, an adult male can grow to 9m long and weigh a colossal 10 tonnes.  That’s as heavy as 9 cars or 133 people!

Classification

(c) Jared Towers

Living things can be organised into different groups.  Species that are alike are grouped together.  This is called classification.

Class:                    Mammals

Order:                   Cetacea

Suborder:              Toothed whales

Family:                  Delphinidae (Dolphins)

Species:                Orcinus orca

Orca are warm-blooded mammals, breathing air and feeding young on their mother’s milk.  Streamlined and powerful, the orca is perfectly adapted for marine life and one of the ocean’s fastest mammal (reaching 56 km/hr). 

Orca are special

Orca are skilled hunters, but with the 2nd largest brain on the planet, they are highly intelligent and lead complex social lives.  In their close-knit families they hunt, rest, play and travel together.  Perhaps the most loyal creature on earth, only death or capture separates an orca from its family.

Distribution

The orca is one of earth’s most wide-ranging animals, found all over the globe but especially in food-rich areas.  They swim up to 150km a day and dive to great depths (what a contrast to captivity!).  Two distinct types of orca are identified: ‘residents’ stay in one area; and ‘transients’ roam widely.

Habitat

A wild orca spends its entire life in the ocean, resting and sleeping in the water.  They can swim up to beaches to grab sea lions, and use ‘rubbing beaches’, swimming into shallows and running their bodies along smooth pebbles.  This is obviously a pleasurable social activity.

Diet

Orcas have a huge appetite, daily eating up to 5% of their body weight.  ‘Opportunistic’, they prey on a wide variety of food: resident orcas catch fish, while transients hunt seals, sea lions, dolphins and even large whales.  Orca can hunt co-operatively, top the marine ‘food chain’ and have no predators.

Adaptations

Orca bodies are modified for life as a sea predator.  Huge kidneys get rid of excess salt; skin is tough and rubbery; blubber keeps them warm and stores food; massive jaws have sharp teeth; strong flippers steering and brake; and a muscular tail fluke propels them through the water.

Behaviour

Sound travels well in water and orcas communicate with calls, clicks and whistles.  They use ‘echo-location’ clicks to navigate and find food.  Orcas leap out of the water or ‘breach’; and ‘spy-hop’, resting vertically in the water looking around. 

Society

Permanent mother-led groups form extended families called ‘pods’.  Though mothers are the primary care-givers, everyone plays a part in caring for the young.  The social life is vital.  Each pod has its own distinct dialect.

Reproduction

Orca live up to 80 years or more.  They mature at about 14 years.  Mating takes place between individuals from different pods and lengthy courtship is thought to occur.  A female produces just one calf every 4-5 years.  Gestation is 17 months and new-borns are around 200kg and 2.5m long.  The calf suckles most of its first year and remains with its family for life.

Born Free Foundation
Broadlands Business Campus, Langhurstwood Road
, Horsham, RH12 4QP, UK - Charity Reg. No. 1070906


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