The pygmy killer whale, Feresa attenuata, is a lesser-known member of the oceanic dolphin family. Despite its formidable name, this marine mammal is distinct from the larger, more commonly recognized killer whale. Its presence in the world’s oceans offers insights into the diversity of dolphin species.
Meet the Pygmy Killer Whale
Pygmy killer whales have a sleek, torpedo-shaped body, dark grey to black dorsally. They exhibit lighter grey or white patches on their belly and around their mouth and chin, sometimes extending onto their flanks. Adults measure 2.0 to 2.6 meters (6.6 to 8.5 feet) in length and weigh 110 to 220 kilograms (240 to 485 pounds). Their head is rounded without a distinct beak, and their dorsal fin is tall and sickle-shaped. These features place them within the Delphinidae family.
Their Ocean Habitat and Diet
Pygmy killer whales inhabit deep, offshore waters in tropical and subtropical regions globally. They are found in the Atlantic, Pacific, and Indian Oceans, often far from coastlines in depths over 500 meters. These dolphins are active predators, primarily feeding on a variety of fish, including lanternfish and tuna, as well as cephalopods such as squid. They hunt cooperatively in groups, using echolocation to locate prey in their oceanic environment.
Social Life and Behavior
Pygmy killer whales are social animals, found in groups of 10 to 50 individuals, with larger aggregations observed. They interact closely within the pod, often swimming in coordinated patterns. Observers have noted various surface behaviors, including breaching, where they launch themselves out of the water, and spyhopping, where they vertically raise their heads above the surface to look around. Vocalizations, including clicks and whistles, are used for communication and navigation, facilitating group cohesion and hunting.
Distinguishing Them From Orcas
The name “pygmy killer whale” often causes confusion, as they differ significantly from the true killer whale, Orcinus orca. They are significantly smaller, about half the length and a fraction of the weight of an adult orca. Their body is more slender, and their dorsal fin is less robust and triangular than an orca’s tall, straight fin. Orcas display stark black-and-white coloration with prominent white eye patches, while pygmy killer whales have a more uniform dark grey to black body with subtle lighter areas. Their ecological roles also differ, with orcas being apex predators that hunt marine mammals, while pygmy killer whales primarily target fish and cephalopods.
Conservation Status and Threats
The International Union for Conservation of Nature (IUCN) lists the pygmy killer whale as “Least Concern,” due to its wide distribution and presumed large population size. However, comprehensive data on population trends and specific threats remain limited. They face challenges including bycatch in fisheries, particularly gillnets, leading to accidental entanglement and drowning. Ocean noise pollution from shipping and seismic surveys can disrupt communication and navigation, affecting foraging success. Habitat degradation and climate change impacts, such as changes in prey distribution, also pose long-term risks.