Like many other cetacean species, killer whales, also called orcas (Orcinus orca) can be identified on an individual basis by their natural markings and differences in fin shape. Orcas have an obvious dorsal fin that varies in shape and size, often with distinctive nicks or scars. The saddle patch also varies from individual to individual in shape, size, color, and scarring. In the case of the Southern Resident Killer Whales, individual identification allows us to maintain a precise census of the population where every individual is known and accounted for.