Feresa attenuata
pygmy killer whale

Feresa attenuata is found around Japan, Hawaii and in the warmer eastern areas of the North Pacific Ocean. It is also found in the West Indian area and around tropical western Africa in the Atlantic Ocean as well as in the Indian Ocean and the Gulf of Mexico. (Ridgway, 1994; Tinker, 1988; http://library.advanced.org/2605/pygkill.htm, 1999).

Feresa attenuata is primarily a species of tropical waters, though it has been spotted in cooler waters off the west coast of Southern Africa and Peru. It prefers sub-tropical and tropical waters usually in deep water in the open oceans and is rarely found in closed water. Pygmy killer whales are believed to be non-migratory, but little is known about their migratory habits. (Ridgway, 1994; Tinker, 1988; http://www.cetacea.org/pkiller.htm, 1999). (Ridgway and Harrison, 1994; Tinker, 1988)

Feresa attenuata is very similar in appearance to melon-headed whales and to juvenile false killer whales. From a distance it is very difficult to tell these three apart. The shape of the head, the dorsal fin and the flippers of pygmy killer whales are different from the other two. The head of Feresa attenuata is rounded and lacks a beak. They have an underslung jaw and white lips, and usually a white patch on the tip of the lower jaw. The skull is asymmetrical and the right jaw is smaller and usually has one less tooth than the left jaw. The teeth are large and conical. There are usually 8 to 11 pairs of teeth in the upper jaw and 11 to 13 pairs of teeth in the lower jaw.

Pygmy killer whales have a sub-triangular, long based, high dorsal fin with a tip that points backward. The dorsal fin is located near the center of the body and lacks rigidity, often inclining to the side. The flippers of pygmy killer whales are moderate in length and have rounded tips.

The body of Feresa attenuata is slender, though the midsection forward is slightly more robust than the midsection back. Pygmy killer whales are not whale sized at all; rather, they are average sized dolphins and part of the family Delphinidae. An adult ranges in length from 2.1 to 2.6 meters and weighs between 110 and 170 kg. The coloring is dark gray to black with some paler markings on the underside, as well as some white on the belly. Feresa attenuata has a groove on the skin of its belly that extends from anterior to the umbilicus to the anus. In both males and females this groove contains the umbilicus, the anus and the genitals. (Balcomb, 1987; Ridgway, 1994; Tinker, 1988; http://www.cetacea.org/pkiller.htm, 1999; http://www.sci.tamucc.edu/tmmsn/29Species/pygmykiller.html, 1999; http://www.gomr.mms.gov/homepg/regulate/environ/marmam/pygmy.html, 1999; http://library.advanced.org/2605/pygkill.htm, 1999).

Longevity in this species is poorly understood.

Pygmy killer whales are described as aggressive animals that have been seen snapping their jaws, beating their flippers and flukes on the surface of the water, and growling. In captivity they elicit fear reactions from other cetaceans. They will charge, bite, and snap their jaws at other cetaceans as well as their trainers. They will often kill all other cetaceans that are in the tank with them. Though aggressive toward other animals pygmy killer whales are shy of vessels.

At the water's surface pygmy killer whales are quite acrobatic. They are often seen leaping, spy hopping, tail slapping, and occasionally bowriding. Social groups of this species are usually made up of approximately 25 individuals. In areas where they are more frequently sighted, such at the Hawaiian Islands, herds contain up to 50 individuals and on rare occasions a few hundred. (Balcomb, 1987; Ridgway, 1994; http://www.cetacea.org/pkiller.htm, 1999; http://www.anca.gov.au/plants/threaten/plans/action_plans/cetaceans/whaleap5p.htm, 1999).

Feresa attenuata make sounds similar to the whistles and clicks of bottlenose dolphins, as well as growling sounds through their blowhole.

The diet of Feresa attenuata includes squid, octopus, and large fish, e.g., tuna and dolphin fish. Pygmy killer whales are also known to occasionally attack groups of small cetaceans, for instance other dolphins. (http://www.cetacea.org/pkiller.htm, 1999; http://www.sci.tamucc.edu/tmmsn/29Species/pygmykiller.html, 1999).

Little is known about predators of pygmy killer whales. Their large size and aggressiveness makes them invulnerable to many predators, but perhaps not to large sharks or larger cetaceans, such as orcas.

Pygmy killer whales are important predators of fish and cephalopods.

There are no negative impacts of pygmy killer whales on humans.

Pygmy killer whales are important members of pelagic ecosystems.

Feresa attenuata is listed in Appendix II of the Convention of International Trade in Endangered Species of Wild Fauna and Flora (CITES). Those listed in Appendix II, as stated on the CITES web site, are "species which although not necessarily threatened with extinction may become so unless trade is subject to strict regulation." As well as non-threatened species that must be subject to regulation in order to control threatened species. (http://www.wcmc.org.uk/CITES/english/index.html, 1999).