Killer Whales are probably the most famous and charismatic member of the ‘toothed’ whales. Known for their high intelligence they have been called the ‘wolves of the sea’.
Largest of the dolphins species, yes they are dolphins, their distinct black and white makings make them easily identifiable. As apex predators they hunt a wide range of prey from fish, seals to other whales, with some pods specialise in hunting a particular prey such as the ones who hunt Stingrays in New Zealand.
In the Southern Hemisphere there are five different ’types’ of Killer Whales – A, B (Small), B (Large), C and D.
Killer Whale by Candela Riveros
Common Name: Killer Whale Other Names: Orca, Orca whale, Blackfish Scientific Name:Orcinus orca Conservation Status: Length: New-born calf up to 2.6 metres, Adults females up to 9.2 metres, Males up to 9.8 metres. Weight: Birth weight is under 160 kg. Adults up to 4 tonnes. Gestation: 12 to 17 months Weaning Age: Approximately 12 months Calving Interval: 3 to 8 years Sexual Maturity Age: Females Approx 4.6–5.4 metres and 10 years, Males Approx 5.2–6.2 m and 16 years Physical Maturity Age: unknown Lifespan: 60+ years Mating Season: Year round Calving Season: Year round Cruising Speed: Protected Since:
Field Identification – Black and white markings. – Grey saddle making behind dorsal fin. – White patch behind the eye. – Large robust body – Large dorsal fin (male high triangular shape/female more dolphin like). – Large paddle shaped peck fins. – Acrobatic and active at the surface.
Taxonomy The Killer Whales is one of the worlds top marine predators. They are the largest member of the Delphinidae family, or oceanic dolphins. Confusingly many dolphin species common names use the ‘whale’ rather their true dolphin heritage, so yes they are dolphins!
The oceanic dolphin family first appeared around 11 million years ago. It is thought that the killer whale lineage branched off soon after and that their closest extant relatives are the snubfin dolphins of the genus Orcaella. Killer Whales like all dolphins are toothed whales and they share similarities with False Killer Whales, the Pygmy Killer Whales and the Pilot Whales.
Description Killer Whales are the largest member of the dolphin family and are easily recognisable by their distinctive black, white and grey coloration and markings. They have a rounded head with no distinct beak. The overall body colour is black with a white eye patch, which is above and behind the eye. They also have a grey saddle patch just behind the dorsal fin. The pectoral fins are paddle-shaped. The underside, jaw, belly and underside to the tail are white.
Killer whales are sexually dimorphic with the males being larger in size and have disproportionately larger peck and dorsal fins than the females. Males dorsal fins are much larger and triangular in shape than the smaller more dolphin shaped females dorsal fins. Adult males will reach a length of up to 9.5 meters and 4 tonnes in weight whereas a female will reach a length of about 8.5–9.2 metres and 3 tonnes in weight.
Killer Whales life in extended family pods that are usually much less than 30 animals. In Australian waters average pod sizes seem to be less than 10. Some pods have been known to specialise in hunting a particular prey such as fish, seals, penguins, stingrays or other whale species.
Southern Hemisphere Types – In the Southern Hemisphere there are considered to be five ‘types’ of Killer Whales.
Southern Hemisphere Killer Whale Types by Albino.orca/Wikimedia Commons
Type A The Type A Orcas look like a ‘typical’ killer whale with a large, black-and-white body with a medium-sized white eye patch and grey saddle after their dorsal fin. They are the largest of the types and are up to 9.5 metres in length. They prefer the ocean ocean where they hunt Minke Whales. They are known to migrate through the Southern Ocean too and from Antarctic waters.
Type B (large) – Pack Ice Orcas The Pack Ice Orcas are smaller than the Type A’s with a large white eye patch, body colouring that is more a medium grey than black and a dark grey patch called the “dorsal cape” that stretches back from its forehead to just behind its dorsal fin. They can often appear to be a brown or yellowish colour due to algae growths (diatoms) on their skin.
They are known for their cooperative hunting of seals amongst the Antarctic pack ice. They have been observed working together to create waves to wash seals off the ice into the water.
Type B (small) – Gerlache Orcas These Orcas are named after the Gerlache Strait in the Antarctic Peninsula where they are often seen. They are smaller than the Type A and B orcas and may also be brown or yellowish colour due to algae (diatoms) growths. Their full diet is not known but they have been seen feeding on penguins and are often seen near penguin colonies.
Type C – Ross Sea Orcas The Ross Sea Orcas are the smallest ecotype with males reaching about 6 metres in length and live in the largest pods. They have a very distinct slanted eye patch and are more grey than black in colour with the dark grey dorsal cape. Again they may appear to be brown or yellowish colour due to algae (diatoms) growths.
They are found off Eastern Antarctica hunting amongst the thick pack ice where they’re only observed prey is Antarctic Cod.
Type D – Subantarctic Orcas The rarest of the southern orca types is the D’s who have identified by a stranding in New Zealand in 1955 and by a few rare sightings at sea. They share the same black-and-white colouring and saddle patch patterns of other orcas but have very different body characteristics. The head is more rounded, almost like a Pilot Whale in shape, they have narrower and shorter dorsal fins, smaller teeth and the smallest eye patches of any of the ecotype which gives them a very distinct appearance.
Their range appears to be in sub-Antarctic waters between latitudes 40°S and 60°S where they seem to be hunting Patagonian Toothfish although their full diet remains unknown.
Distribution and Movement Patterns Killer Whales are found across the oceans of the world. They are most abundant in colder waters like Antarctica, Norway, and Alaska, they can also be found in tropical and subtropical waters.
Australia – Killer Whales have been recorded in all states but there are currently no known key locations for them in Australian waters. They are most commonly seen in cooler waters around southern Australia, particularly off Tasmania.
South of Australia Killer Whales are frequently seen in the Antarctic waters south of 60° S and have been recorded around Heard and Macquarie Islands. Macquarie Island appears to be a key location with them being regularly sighted there.
It was thought that Killer Whales only hunted along the outer fringe of the pack ice during the summer months and then migrating away to warmer waters during winter. Sightings deep into the ice during winter months with the presence of small calves have now shown that Killer Whales are the only species of whale to breed in Antarctic waters.
In other parts of the world Killer Whales show a complex population structure which is described as Resident, Transient and Offshore. In Australian waters there could be at least three separate locations where Killer Whales are found: continental Australia, subantarctic and the Antarctic. These populations could be severely fragmented with minimal interaction between different Killer Whale ‘eco-types’. This suggests there is great danger for the potential loss of particular subpopulations, and they’re associated genetic diversity and social culture.
Global – The Killer Whale is probably the most cosmopolitan of all whale species and may be seen in any marine area. They can be found throughout all oceans from the tropics to the poles, though they are most numerous in coastal waters and cooler regions where prey abundance is high.
Population The widespread nature of Killer Whales with local and transient populations makes estimating global population size and distributions very difficult. Current estimates are based on scientific studies and random sightings.
In Australian waters Killer Whales have not been well surveyed apart from around Macquarie Island and in Antarctic so the total number of animals is unknown but thought to be less than 10,000. The number and abundance of particular subpopulations of Killer Whales is also uncertain due to lack of data.
There were 324 sightings recorded at Macquarie Island between 1994 and 1999 with one confirmed re-sighting which along with other evidence suggests that the whales revisit the island each summer.
Scientific studies from the Eastern-North Pacific have distinguished two or three types of Killer Whale, each with differences in their genetics, coloration, external morphology and ecological preferences. It has been suggested that this pattern might be universal and thus could apply to Killer Whales found in Australian waters.
In the Southern Ocean/Antarctic waters south of 60° S it is estimated that there may be as many as 80,000 Killer Whales.
There is great concern that the effects of whaling, over fishing, pollution, habitat disturbance and climate change may have had devastating effects on localised populations. Therefore all populations must be considered important for the long-term survival of Killer Whales.
World Killer Whale Population – Here are some estimated numbers of Killer Whales.
North-eastern Pacific: Estimates a total population of 1500 Killer Whales. Alaska – 850 (117 off the Queen Charlotte Islands, 260 “resident” whales and 75 “transient” whales off eastern and southern Vancouver Island) California – 184 Mexican – 65
North-western Pacific: Estimates a total population of 1900 Killer Whales. Japan – 1200
Southern Indian Ocean: No estimates for this area although there are reports of a strong decline in Killer Whales number in the coastal waters of Possession Island between 1988 and 2000.
Antarctica: Estimates a total population of 80,400 Killer Whales south of the Antarctic convergence.
North Atlantic: Estimates a total population of 483 to 1507 Killer Whales. Norway – 483 to 1507 Norwegian and Barents Seas – 3100 Icelandic and Faroese waters – 3100
Habitat Killer Whales have a wide range of habitats due to their cosmopolitan nature and ability to inhabit all oceans. They are found both in costal waters and out into the deep ocean. They are more common in cold, deep waters where abundant food may be found such as along the ice edge during the Antarctic summer.
In Oceania Killer Whales are often seen in coastal waters, along the continental slope and shelf as well as around subantarctic Islands. In Australia they tend to be found off the southern states, particularly around Tasmania and Macquarie Island. In New Zealand they can be sighted around both islands.
As the Humpback Whale population has recovered from whaling Killer Whales have again started to follow their annual migrations hunting the Humpback calves. So there have been more frequent sightings off the Australian east coast in recent years. Famously a pod of Killer Whales worked with the whalers to hunt Humpbacks Whales out of Eden in NSW during the 1920-30’s.
Killer Whales will gather around subantarctic Islands such as Macquarie Island during the summer months to hunt seals and penguins.
In Antarctica they hunt along the ice edge. Family pods including calves have also been seen deep within the ice which indicates they may stay year round and breed there.
Behaviours Killer Whales are highly intelligent and social animals that live in extended family pods of normally less than 20 animals. Daily behaviours will include hunting, traveling, socialising and resting. They may temporary gather together in greater numbers to socialise with other pods or where food is abundant.
Killer Whales are known for their acrobatic displays of breaching, tail and peck slaps. They are also known to spyhop, where they raise their heads clear of the water to see what is going on above the surface.
The diet of Killer Whales is somewhat determined by what prey is available where they live but in many cases pods have specialised in hunting a particular prey such as fish, stingrays, seals or other whales. They are very well known to work together using coordinated hunting strategies. This taught/learned behaviour as well as pods having their own unique set of calls has many scientists realising that individual pods have their own distinct culture and language.
Social Structure – It is thought that only elephants and higher primates have more complex social structures/societies than Killer Whales. Strong family pods consist of an eldest female (matriarch) and her children. These family pods create very strong, complex and stable social groups. Given how long Killer Whales can live such as the famous Granny (J2) who was believed to be over 100 years old (she was probably no more than 80 years old) these family pods containing many generations that stay together for life. Bonds between males and their mothers are thought to be particularly strong. Members will only leave the family pod for short periods of time to hunt and mate.
Just to give an insight into the complexity of Killer Whale society in areas such as Alaska the basic unit is the family or matriarchal pod consisting of a grandmother and her offspring. Then comes the Clan which is composed of pods that share a common language (similar dialects) and have a common but older maternal heritage. Clans ranges overlap and allow whales to meet and mingle with other Clans. These mingling Clans form the overall Killer Whale Community. Whilst these Clans may mingle they do not necessarily share the same language (vocal patterns).
Vocalisation – Whales are heavily dependant on their sense of hearing for orientation, navigation, hunting and communication. As toothed whales Killer Whales have an advanced use of sounds for navigation, hunting and communicating with one another. They are known to produce sounds in three categories: clicks, whistles, and pulses. Scientist believe that the click sounds are for orientation and navigation but have also been heard when whales are interacting with one another.
The prey of a particular pod may also determine how much and the types of sounds they may make. Killer Whales who mainly eat fish are known to make a lot of sounds whereas those who hunt seals are almost silent.
The members of a pod will all use similar calls which are known as a dialect. Dialects are made up of a specific numbers and types of discrete, repetitive calls. These complex call patterns and structure are distinctive within matrilines and stable over time. When a calf is born the family pod will use its family-specific calls more often than normal to teach to the new calf. It is believed that the use of family dialects is an important way of maintaining group identity and cohesiveness. How closely related different pods are can be determined by how similar their dialects are. Over time variations in each dialect tend to grow.
Intelligence – Killer Whales are known for their high intelligence. They have the second-heaviest brains amongst marine mammals after Sperm Whales (who by the way have the largest largest brain of any animal). There are many examples of this intelligence from their curiosity, ability to learn new things and problem solve. They are also known to train their young, teaching them hunting skills. In Antarctica pods have been observed working together to create waves to wash seals off the ice. In Alaskan waters Killer Whales are known to steal fish from fishing longline. The fishermen have tried many techniques to stop the whales stealing the fish and the whales have been able to overcome each of them. Sadly captive Killer Whales have been trained to perform like circus animals.
Feeding Killer Whales are apex predators that prey on a wide variety of animals using an amazing variety of specialised hunting techniques. They have been called the wolves of the sea!
In the Southern Hemisphere waters Killer Whales are known to eat fish, squid, stingrays, turtles, sharks, seals, dolphins, Dugongs and other whales. This wide variety of prey, their high intelligence and cultural complexity means that Killer Whales have developed many specialised hunting techniques. It also means that pods within similar geographic areas may hunt very different prey. This can be seen in Alaska where some pods hunt fish whereas other only hunt seals.
Australia – In Australian waters Killer Whales are known to hunt seals and other whale species. As Humpback Whale numbers recover more and more sightings are being make of Killer Whales following the migration to hunt the Humpback calves. In South Australia they have been seen hunting Sperm Whales.
Many sightings of Killer Whales have been seen at the recently discovered Bremer Bay Canyon bio hotspot off the Western Australian south coast. Here they have been seen hunting squid and other whales including Beaked and Blue Whales.
Famously Killer Whales actively worked alongside whales of Eden on the NSW coast during from the 1800’s up until 1930. The Killer Whales were known to alert the whalers by banging their tails on the water and then would accompany them on the hunt. A male Killer Whale named Old Tom would hold onto the harpoon rope forcing the whale underwater to drowned it. The whalers would leave the carcass moored in the bay so the Killer Whales could eat the tongue.
Killer Whales have also been known to steal fish from fishing longlines throughout their range, including off Tasmanian and in subantarctic waters.
New Zealand – In New Zealand Killer Whales have developed an unusual diet of stingrays, eagle rays and electric rays. They are the only known Killer Whales to do this. They have been observed hunting in the shallow waters of harbours such as Kaipara, Tauranga, Whāngārei, Waitematā and Wellington.
Eating these rays can be dangerous because of their poisonous spines, so the whales have developed special hunting techniques where they seize the rays by the head or by tip of the tail in order to avoid the barb halfway along their tails.
Antartica – Observations in the Antarctic waters have reported Killer Whales hunting Humpback and Minke Whales in packs. They have also been observed working together to create waves to wash seals off the ice.
The Type A’s occurs offshore in deeper water and preys on Minke Whales. The Type B’s are found in inshore waters, around pack ice and the Antarctic Peninsula and appear to target seals. The Type C’s inhabit the inshore waters of East Antarctica where they have been seen eating Antarctic Toothfish. The Type D’s seem to inhabit deeper offshore waters between latitudes 40°S and 60°S where they have been seen eating Patagonian Toothfish.
Whaling – During the large scale commercial whaling of the 20th century Killer Whales were observed opportunistically scavenging the whales carcasses found around whaling stations. Whales that die naturally sink to the ocean floor out of the diving range of the Killer Whales so this artificial and easy to obtain food source allowed an unnatural shift in diet and numbers of the scavenging Killer Whales. When major whaling opposition ceased in the 1970’s the Killer Whales were forced to find alternative food sources and may have turned to hunting seals and other whales.
Life Cycle The life history of Killer Whales in Australian waters is limited so this information is based on Killer Whale populations elsewhere in the world.
Apparently there is no specific mating season for Killer Whales with mating occurring year round. Males will seek out females from other pods to mate with, preventing inbreeding. There are no known breeding grounds in Australian waters.
Pregnancies last between 12 to 17 months and they give birth to a single calf. Calves are about 2.6 metres long and 120 to 160 kg in weight at birth. Their dorsal fin, peck fins and tail flukes are flexible and gradually stiffen within the first few days. As there is not specific breeding season birth can occur at any time. Breeding intervals are between 3 to 8 years. The calf will begin being weaned at 12 months of age and completely weaned by 2 years of age. Observations suggest that all members of the pod participate in the care of the young.
Infanticide has been observed in both captive and wild Killer Whales and is thought to be similar to such behaviour seen in other dolphin species such as Bottlenose Dolphins. Unfortunately up to 50% of all calves do not make it through their first year of life.
Females become sexually mature around 10 years and 4.6–5.4 m in length and reach peak fertility around 20 years of age. Males reach sexual maturity at 16 years of age and 5.2–6.2 m in length. Females can breed up until 40 years of age. Killer Whales along with Beluga, Narwhals, Short-finned Pilot, False Killer and Sperm Whales, as well as humans are the only known species that go through menopause. Killer Whales are also one of the few species that continue to live long after they have finished breeding. The lifespans of wild females average 50 to 80 years, males to perhaps 60.
The natural mortality rate amongst wild Killer Whales is around 5% per year.
Threats Like all marine mammals Minke Whales have a number of natural and man made threats. Natural – Illness and old age. As apex predators life is extremely hard. Man Made – Overfishing and habitat loss have greatly impacted Killer Whale populations. Pollution, climate change, acoustic disturbance and entanglement also play significant factors affecting them.
References/Sources Australian Department of the Environment, Canberra Australian Antarctic Division NZ Department of the Environment NOAA Fisheries Whales, Dolphins and Porpoises by Mark Carwardine Whales, Dolphins & Seals: A Field Guide to the Marine Mammals of the World by Hadoram Shirihai and Brett Jarrett
