English: Killer whale
The species shows considerable sexual dimorphism.
Males are generally larger than females and adult
males have a distinct tall dorsal fin.
Length: 5.0 - 8.5 m (female) / 7.0 - 9.8 m (male)
Weight: 3.3 - 7.5 ton (female) / 5.9 - 10 ton (male)
Habitat and distribution:
The killer whale is a cosmopolitan species. Although kiler whales tend to be more numerous in cold water, they can be found in all the oceans of the world, from the Antarctic to the tropics. Some killer whale populations (e.g. in the US/ Canada) are among the best studied cetaceans in the world, but surprisingly little is known about killer whale behaviour and ecology in most other areas. Killer whales tend to roam over large areas looking for food which can be a specific type of prey such as fish or warm-blooded prey including other marine mammals and seabirds. The distribution of some populations is clearly influenced by the migration of their prey species (fishes or marine mammals). Killer whales in Chile are poorly known. They have been sighted in Chilean Patagonia predating on sei whales and sea lions.
Due to their dietary specialisation, some populations of killer whales could be affected by a reduction of their food supply due to overfishing. Some killer whales are known to have learnt to depredate fishing gear making them unpopular with fishermen. Being at the top of the food web means that killer whales accumulate and store toxins aquired via their prey. Some killer whales in North America are among the most contaminated mammals on the planet. Agricultural runoff, chemical industry and oil spills are some sources of pollution in the marine environment with toxins accummulated in fish and other prey being absorbed by killer whales when they feed on these contaminated animals (including accumulation of persistent organic pollutants such as PCBs and DDTs). These pollutants may cause reproductive disorders and decrease immune responses.
- Ford, J. K. B. and Ellis, G. M. 2006. Selective foraging by fish-eating killer whales Orcinus orca in British Columbia. Marine Ecology Progress Series 316: 185-199.
- Häussermann, V., J. Acevedo, G. Försterra, M. Bailey and A. Aguayo-Lobo. 2013. Killer whales in Chilean Patagonia: additional sightings, behavioural observations, and individual identifications. Revista De Biologia Marina Y Oceanografia 48(1): 73-85.
- Ross, P. S., Ellis, G. M., Ikonomou, M. G., Barrett-Lennard, L. G. and Addison, R. F. 2000. High PCB concentrations in free-ranging Pacific killer whales, Orcinus orca: effects of age, sex and dietary preference. Marine Pollution Bulletin 40: 504-515.
- Taylor, B.L., Baird, R., Barlow, J., Dawson, S.M., Ford, J., Mead, J.G., Notarbartolo di Sciara, G., Wade, P. & Pitman, R.L. 2013. Orcinus orca. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>.