In the marine environment, Orcas rely on complex communication in order to navigate, forage, locate each other, and express their moods. The most notable form of communication is vocal. Orca vocalizations have now been well-documented by researchers who use hydrophones to record their sounds. These sounds consist of whistles, buzzing sounds, and screeches. Among Resident Orcas near BC, each pod has its own style of calls, or dialect, and this is thought to help maintain group cohesion.

 
photo M. Noonan

Like many other odontocetes, Orcas are also equipped with echolocation. In dark waters where visibility is low, echolocation aids in finding food and in navigation. Echolocation consists of a series of clicks produced inside the head of the whale. The sharp sounds leave the animal through its forehead, or melon, and then rapidly travel through the water. The sounds bounce off any nearby objects or obstacles and the echoes return to the whale and are picked up by a hearing mechanism in its lower jaw. The whale brain is able to process these returning clicks in a way that allows the whale to maintain a three dimensional sense of its surroundings.

Resident fish eating Killer Whales vocalize loudly and often. But Transient mammal eating Killer Whales are characteristically much more quiet. Since their mammalian prey have good hearing in the range of Killer Whale calls, it is thought that Transients avoid making calls so as not to alert their prey to their presence.

Orcas also communicate through body language. Underwater bubbling, breaching, tail slapping, body quivering, and head nods are just a few examples of movements that whales may make to display aggression, submission, excitement, etc.