The killer whale is one of the most recognizable cetaceans. Its black and white coat as well as the distinctive shape of its dorsal fin make it easy to identify.
Environment and behavior
Killer whales are gregarious creatures. A pod can comprise just a few animals, or several dozens. Social ties are very strong between pod members, particularly between a mother and her calves. There is a clearly-established hierarchy within the pod, shown in a variety of behaviors (biting, jaw-snapping, tail-slapping, head-butting and more). The basic structure is matriarchal: the females are the ones that guide and run the pod. It is probably due to their importance in the group that female orcas can undergo menopause, which is fairly rare among the planet's species. Despite these shared characteristics, killer whales can behave very differently, depending on where they live, since their culture is passed down from one generation to the next. There are 10 ecotypes (sub-species), whose lifestyles can be very far removed from one another.
Diminished supply of fish: The decline in dietary resources caused by overfishing and damage to their habitats is one of the greatest threats encountered by killer whales. The populations that live in the North and specialize in hunting salmon are the ones most affected by this. Chemical contamination: Because killer whales are at the top of the food chain, they ingest the chemicals (especially PCB) accumulated in the flesh of their prey. Populations that eat large prey like marine mammals have been hurt more by this than the rest. Newborns suffer greatly from this bioaccumulation, since a very large proportion of the accumulated pollutants are eliminated through their mothers' milk. It is estimated that 90% of pollutants are transmitted to the first baby, which considerably increases the risk of mortality.