Orca
| Scientific Name | Orcinus orca |  | |
| English Common Name | Orca | ||
| Taxonomy | Class: Mammalia Order: Cetacea Sub-order: Odontoceti Family: Delphinidae Genus: Orcinus Species: orca There are many small and distinct orca populations around the globe, although orca taxonomy is not yet fully understood, the term species complex seems to be appropriate. As more research is focused on orcas in regions beyond the northeast Pacific and northeast Atlantic, the status of the various populations and forms may become clearer and will likely develop to fully reflect the diversity of behaviours, for example the North-eastern Pacific population of orcas is subdivided into reproductively isolated, genetically, morphologically and behaviourally distinct forms: mammal hunting transients, fish eating residents and the recently discovered, lesser known, “offshore” pods. | ||
| Behaviour | Orcas are known to be highly social animals and stay together their entire lifetime in matrilineal pods. Pods are known to have their own “dialect” and they are highly active and acrobatic and are frequently seen breaching, spy-hopping and engaging in other play behaviour. They are extremely fast swimmers and despite their name, there is no evidence of them showing any aggression towards man in the wild. | ||
| World Distribution | Being found in all oceans of the world, orcas are one of the most
widely distributed cetaceans although their range is not thought to be
continuous. They are more frequently observed in cooler waters, e.g. –
Norway, Canada and Antarctica, although populations do exist in warmer
more tropical waters, e.g. – Papua New Guinea and the Mediterranean
Sea. Preferred habitat can vary from shallow bays and inland seas to
deep offshore waters over the continental shelf. | ||
| Morphology | The distinctive black, white and grey markings of the orcas make them one of the most easily recognisable cetaceans in the world. Their large, heavy and robust bodies are predominantly black with a white eye-patch, chin, chest and belly. Each individual orca has an identifying grey saddle patch behind the dorsal fin and this feature is used to identify individuals known to researchers. Flippers are large and paddle-shaped whilst the flukes are black on the upper-side and white on the underside. The orca is beyond doubt, the largest member of the dolphin family with newborns measuring 2.1 – 2.5 m and weighing approximately 180 kg and adults measuring between 5.5 – 9.8 m and weighing between 2.6 – 9 tonnes. There is obvious sexual dimorphism amongst orcas with the males being substantially larger and longer than females and possessing an exceptionally large dorsal fin; height can exceed 6ft!! The diet of orcas varies with their geographical location and their pod’s specialisation. For example, some pods are known to eat mostly fish whilst others are known to predate on other marine mammals. Others may have a more mixed diet, depending on prey availability. | ||
| Threats | The primary threat is directed hunts for the captivity industry. Other threats include habitat degradation, decline in prey availability and both chemical and noise pollution. | ||
| Status | No estimate of total abundance for the species is available however individual population figures do exist | ||
| Conservation Activities | CMS Appendix II IUCN – Lower Risk (conservation dependant) – awaiting re-evaluation | ||
