Orca (or Killer Whale)
Killer Whale (c) E. Hawkins
- Killer Whales are the largest members of the dolphin family.
- Length: Adult: Male 5.1-9.6m; Female 4.6-8.2m; Newborn: 1.8-2.1m
- Weight: Adult: Male 8-9 tonnes; Female up to 4 tonnes; Newborn: 180kg
- Colouration: Killer Whales have striking colouring- the dorsal (top) part of the body is black with a pale white-grey “saddle” behind the dorsal fin. Oval-shaped white eye patches are found behind and above each eye. The chin, throat, central length of the underside and the undersides of the tail flukes are also white. Individuals are able to be identified by their markings and the shape of both the saddle patch and dorsal fin.
- The mouth of the Killer Whale is large and well adapted for hunting. They have 40-50 conical shaped teeth that point slightly backwards and inwards. The upper and lower teeth interlock which aids in gripping large prey and tearing it into smaller pieces which are easier to swallow.
- The dorsal fin of a Killer Whale can reach 1.8m high in males and is shaped like an isosceles triangle. Immature male and the female dorsal fins are also large reaching about 0.91m high but are falcate (curved) in shape.
- The dorsal fins of Killer Whales often have nicks, cuts, scars and indentations which can also be used for identification.
- The paddle-shaped pectoral fins of Killer Whales are broad and rounded and can reach a length of 1.8m and a width of 0.91m.
Biology & Ecology
- Killer Whales are carnivorous top predators.
- They are fast and skilful hunters and sometimes known as “the wolf of the sea” as they can be fierce hunters with well-organised techniques. No cases of Killer Whales attacking humans in the wild have been documented.
- Unlike other species which follow regular migration routes each year, Killer Whales travel according to the availability of food.
- The diet of Killer Whales depends on the population and geographic area.
- Generally, transient populations will feed on a variety of animals including sea lions, elephant seals, harbour seals, porpoises, sharks, fish, penguins, smaller whales such as belugas and even large baleen whales such as grey whales. Resident populations tend to feed primarily on fish species such as salmon or herring.
- In the wild, Killer Whales have a lifespan of 80-90yrs (female) and 50-60yrs (male).
- The age of maturity for Killer Whales varies between genders, with females reaching maturity between 11-20 years and males at 20 years of age.
- Calving season for Killer Whales is year-round with a peak in winter. The gestation length is generally 13-17 months while the period between calves in the wild is 3-5 years.
Behaviour & Social Organisation
- Killer Whales are found in all oceans of the world but are seen more often in cooler waters (especially Polar Regions) than in the tropics and subtropics.
- Sightings of these animals range from the surf zone to the open sea although usually within 800km of the shoreline.
- Killer Whales generally live in pods consisting of several females, calves, one or more males and/or juveniles. The number of individuals in a pod varies extensively from 1 to 50, although temporary joining of pods can form superpods with 150 or more individuals.
- Some pods are matrilineal in structure and consist of a mother and her offspring who stay with her for life. These resident pods are generally stable, consistent family groups with several generations travelling together. Transient pods appear to be more fluid where individuals come and go and these groups often contain unrelated females with offspring.
- Mothers are very protective of their calves and Killer Whales are known to protect and care for sick and injured companions.
- Killer Whales display many different types of behaviours including breaching, lobtailing, spyhopping, tail slaps, pectoral fin slaps and dorsal fin slaps. Other behaviours of these animals include speed-swimming and logging where the whole pod faces in the same direction.
- Killer Whales can travel up to speeds of 55km/h.
- Killer Whales are occasionally sighted off Byron Bay in Humpback Whale season.
- Vocalisations of Killer Whales fall into 3 groups- whistles, discrete calls and clicks.
- Discreet calls are thought to function as social signals between resident pod members. Call and whistle rates are highest when Killer Whales are socialising.
- Sound recordings have shown that each pod has its own “dialect”. Each pod has some sounds in common with other pods and other sounds that are unique to its own pod.