Hobbies And Interests
Social Structure
Orcas travel in groups called pods, in which all members are closely related; a group of pods traveling together forms a community. Three types of killer whales exist in the wild: the resident, transient and offshore varieties. Although all three belong to the same species, they seldom interact with one another, exhibiting differing physical and behavioral characteristics. Residents travel in pods of five to 50 individuals, whereas transients prefer to travel alone or in limited groups. Offshore whales travel in groups of 30 to 60 individuals away from coastal waters. While resident orcas travel predictable paths, transients swim erratic routes up and down coastlines. During breeding season, males may mate in different pods to guard against the deleterious effects of inbreeding.
Echolocation
Killer whales use echolocation underwater to find prey and guide their movements. Killer whales produce short sounds, described as "clicks," often beyond the range of human hearing, concentrated by an organ on the forehead called a melon. The sounds bounce off objects in the light-deprived water and echo back. The orca picks up the reverberations through its jaw. Objects nearer the animals compress sound waves, returning higher frequency sounds than objects that appear farther; this concept is known as the Doppler Effect. Orcas produce surprisingly clear mental images using echolocation, even to the point of differentiating between two types of fish.
Communication
Each matriline -- a group of orcas comprising a female and her offspring -- has its own pulsed call signature, with those arising from similar matrilines deriving analogous call signatures. These pulsed calls, made of repeating patterns, carry for long distances underwater and usually announce territories or breeding readiness. Orcas do not mind if enemies or prey species intercept these calls.
Whistles -- high-frequency emissions that human ears cannot detect -- tend to carry for shorter ranges and signify communication within particular pods. In a study published by "Behavioral Ecology and Sociobiology", Volker Deecke, a researcher from the University of British Columbia, and Rudiger Riesch of the University of Oklahoma hypothesized that the specificity of whistles excludes non-related individuals because this means of communication keeps pods together, identifies relatives and organizes behaviors such as hunting or calling pod members to partake in a kill.
Body Language
Although orcas can communicate vocally with one another, they also engage in various displays to socialize, warn others or engage humans. Whale-watching companies conduct numerous tours each year, exploiting orca surfacing behaviors to wow captive audiences. One of the most anticipated orca behaviors occurs when the killer whale breaches, or propels its mass into the air. When an orca smacks the water with its flipper or tail, called a fluke, the animal may be in a playful mood, whereas lobtailing -- the act of violently sweeping and waving its fluke -- suggests aggression. Logging occurs as groups of orcas lie parallel to one another and face the same direction, signifying that the animals are resting. Spyhopping -- when an orca raises its top half completely out of the water -- seems comical to the human observer, but allows the orca to observe what is happening above water.
Feeding
Resident and transient orca communities differ in the type of prey each consumes. Residents prey on fish species, while transients prefer to hunt other marine mammals. While transients must actively hunt for food, residents generally scoop up prey such as salmon swimming toward them. Orcas consume close to 400 lbs. of food per day, engaging in diving behaviors to locate and capture prey. Transients tend to take longer dives than residents, up to 15 minutes as compared to about 3 minutes, respectively. Before plunging, killer whales inhale deeply several times and make deep arches from their backs. Orcas usually dive together and surface in unison.