The False Killer Whale, Pseudorca crassidens, is a large, highly social species of oceanic dolphin found across the world’s tropical and warm temperate waters. Despite its common name, it belongs to the Delphinidae family, making it a dolphin rather than a true whale. This sleek, dark predator occupies a high trophic level in the marine food web, primarily inhabiting the deep, offshore regions of the open ocean. Its wide global distribution and complex social structure make it a fascinating subject in marine biology.
Identification and Naming
The species earned its common name because its skull structure, described from a fossil in 1846, was similar to that of the Orca, or Killer Whale. The scientific name, Pseudorca crassidens, translates to “false orca with thick teeth,” reflecting this comparison based on internal anatomy. Externally, the False Killer Whale is distinct from its namesake.
The False Killer Whale has a uniformly black or dark gray body that is long and slender, lacking the prominent white markings of the Orca. Its head is rounded and tapers smoothly without a pronounced beak. A distinguishing feature is the unique shape of its flippers, which have a noticeable S-shaped curve on the leading edge. Males reach lengths of up to six meters, generally larger than females, which grow to about five meters.
Global Distribution and Social Behavior
False Killer Whales are found worldwide in deep, open ocean environments (pelagic waters), across tropical and warm temperate zones. While they typically remain far from shore, some populations, such as those near the Hawaiian Islands, utilize nearshore waters. Their broad distribution makes a global population estimate difficult, as they are rarely observed systematically across their entire range.
The species is known for its intense sociability, forming highly cohesive groups with stable, long-term bonds. Pod sizes are variable, often seen in groups of 10 to 20, but these smaller units may aggregate into massive temporary schools of several hundred individuals. They frequently engage in cooperative behaviors, including forming mixed-species groups, most notably with the Common Bottlenose Dolphin. This strong social cohesion is also thought to be a factor in the species’ tendency toward mass strandings, where entire groups can become beached together.
Diet, Hunting Strategies, and Longevity
False Killer Whales are active, opportunistic predators that primarily consume large, fast-swimming pelagic fish and squid. Their diet includes commercially important species like tuna, mahi-mahi, and wahoo, which they hunt in coordinated groups. They are deep divers, capable of descending hundreds of meters and sustaining dives for up to 18 minutes to pursue prey.
Coordinated hunting involves sophisticated techniques, such as herding schools of fish, and they have been observed sharing large catches among pod members. Females experience menopause, typically between 45 and 55 years of age, yet remain in the social group. This post-reproductive lifespan allows them to contribute to the care and protection of younger relatives, supporting the pod’s overall survival. The maximum documented lifespan reaches up to 63 years for females and 58 years for males.
Threats and Current Conservation Status
Globally, the False Killer Whale is assessed by the IUCN as Near Threatened, reflecting concerns over pressures across its wide range. The most significant human-caused threat is interaction with commercial fisheries, particularly bycatch, where dolphins are unintentionally hooked or entangled. They also engage in depredation, actively removing fish from longlines, which leads to conflict with fishermen.
Specific subpopulations face far greater risks, such as the insular population around the main Hawaiian Islands, which is listed as Endangered under the U.S. Endangered Species Act (ESA). This small, distinct group has been severely impacted by fishery interactions and a declining population trend. Other threats include the accumulation of environmental contaminants, which concentrate in these top predators, and exposure to loud underwater noise, which interferes with their navigation and communication.