Orca Matt Binns/Flickr

Orca

Did You Know?

  • They are the largest member of the dolphin family
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Mostly black in colour with a light grey saddle behind the dorsal fin and a distinct white oval shaped horizontal patch behind the eye. The belly, underside of the jaw, and underside of the tail are also white. Mature males have a tall triangular-shaped dorsal fin while females and juveniles have a smaller, more curved dorsal fin.

Size

Adults reach a length of 10 m, dorsal fin up to 1.8 m in height.

Behaviour

Diet

They prey on whales, dolphins and seals as well as fish; known to “play” with their food.

Movement

They can be found feeding, travelling, resting or socialising in Australian waters; however they are rarely seen at the surface for long periods making them difficult to spot. Occasionally they may hold their head out of the water, known as ‘spy hopping’ which may help them to see their surroundings.

There is evidence of medium range migration that shows some correlation with the migration and breeding of target prey species such as fur seals and Humpbacks. Orcas from other parts of the world are known to make seasonal movements and ‘Australian’ Orcas may possibly migrate between Antarctica and mainland Australia, following the seasonal migration of their prey. Their location might be revealed by the presence of birds attracted to the pod during times of hunting.

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What to Observe

  • How many adults and calves

  • Behaviour (stationary, milling, feeding, jumping, rolling, waving fins)

  • Distance from shore

  • Weather

  • State of the Sea

  • Photograph of dorsal fin and tail

Climate Adaptations

Orcas are top predators, with their movements and behaviours shaped according to the seasonal movements and availability of their prey. Warmer ocean waters and currents will change the distribution of small fish and invertebrates that occupy the bottom of the food chain, and in turn, alter the distribution of larger marine species such as seals, penguins and whales. Orcas will respond to the changes in the bottom of the food chain by changing where they feed and what they feed on. We expect them to alter their diet and feeding locations in response to changes in the distribution of prey.

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When and Where

When To Look

  • Sighted sporadically around Australia at different times of year
  • On the east coast in October
  • On the west coast in July coinciding with Humpback migration (looking for calves separated from their mothers)
  • Feeding activities focus on southern shorelines near seal colonies during spring and along whale migration routes during winter

Where To Look

  • All around the world in most major oceans and seas with occasional forays into rivers
  • Common in colder waters like Antarctica and the Arctic
  • Annual sightings at Eden, NSW in spring and Exmouth, Western Australia in winter
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What Else?

During the times of commercial whaling off Eden, NSW, resident Orcas would help whalers round up Baleen Whales in Twofold Bay. As a reward, they would receive the lips and tongue of the catch. This cooperative relationship endured over many decades.