Feresa attenuata Gray 1874
Creators: name: Russell A. Mittermeier
name: Don E. Wilson
Publisher: name: Lynx Edicions
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Mammalia
Cetacea
Delphinidae
Feresa
Feresa attenuata

description: 27.
Pygmy Killer Whale
Feresa attenuata
French: Orque pygmée / German: Zwergschwertwal / Spanish: Orca pigmea
Other common names: Slender Blackfish, Slender Pilot Whale
Taxonomy. [leresa attenuata Gray, 1874,
“South Seas.”
This species is monotypic.
Distribution. Cosmopolitan tropical and subtropical distribution between ¢.40° N and ¢.35° S, including the Gulfof Mexico and Arabian Sea.
Descriptive notes. Total length 210- 260 cm; weight up to 225 kg. Neonates are ¢.80 cm long and weigh 15-20 kg.
Male Pygmy Killer Whales may be slightly larger than females. The Pygmy Killer Whale has moderately robust body that tapers posteriorly into shallow tailstock. Head is bulbous and rounded, with no visible beak, and flippers are slender and slightly curved, with rounded tips. Dorsalfin, positioned about halfway along body, is tall and falcate. The Pygmy Killer Whale has dark-gray to black skin, with dark, narrow dorsal cape that dips below dorsal fin, contrasting with slightly paler gray flanks. Lips may be pale gray to white, and a narrow white patch runs ventrally along body, widening at urogenital area. Older adult Pygmy Killer Whales usually have scars over back and flanks from cookie-cutter sharks (Zsistius spp.). There are 11-13 pairs of large, pointed teeth in upperjaw and 8-11 pairs in lower jaw.
Habitat. Offshore, deep water, associated with warm currents of tropical origin. The Pygmy Killer Whale is widely distributed, but it does not appear particularly abundant in any region. It is relatively boat-shy, so lack of data could simply be due to limited observation opportunities. The Pygmy Killer Whale does seem to prefer tropical climates, and most observations in higher latitudes have been associated with warm water currents. Itis primarily found in offshore, deeper waters and most frequently observed in the eastern Pacific Ocean, offJapan, and off Hawaii.
Food and Feeding. The Pygmy Killer Whale is thought to forage mostly on cephalopods and fish. Commonly documented prey in carcasses from strandings and incidental catch include various species of squid from the families Ommastrephidae and Onychoteuthidae. Echolocation frequencies are comparable to other similarly sized delphinids with similar diets, such as Risso’s Dolphin (Grampus griseus). The Pygmy Killer Whale will attack other species of delphinids, such as various species of Stenella, in the purseseine yellowfin tuna (Thunnus albacares) fishery, and this aggression may be predatory.
Breeding. There is no specific information available for this species, but the estimated body length of the Pygmy Killer Whale at sexual maturity is ¢.200 cm.
Activity patterns. The Pygmy Killer Whale generally does not approach boats, but occasional bow riding has been reported. Breaching and spy hopping also have been observed. When traveling, Pygmy Killer Whales will swim in coordinated “chorus lines.”
Movements, Home range and Social organization. Group sizes are generally small consisting of 12-50 individuals, although groups of more than 100 individuals have been reported. Social association is thought to be strong and stable, especially given that groups of Pygmy Killer Whales are known to mass strand, a tendency that seems common to cetacean species with strong social bonds, such as pilot whales. No migrations or regular movement patterns have been documented for the Pygmy Killer Whale, and populations appear to be resident to the regions where they occur. Strong site fidelity has been documented off Hawaii, and fisheries operating off Sri Lanka and the Lesser Antilles incidentally catch Pygmy Killer Whales throughout the year.
Status and Conservation. CITES Appendix II. Classified as Data Deficient on The [UCN Red List. Overall abundance estimates and population trendsfor the Pygmy Killer Whale are currently unavailable. There are ¢.38,900 individuals in the eastern tropical Pacific Ocean, ¢.800 individuals off Hawaii, and ¢.400 individuals in the northern Gulf of Mexico. Although infrequent observations of the Pygmy Killer Whale may be due in part to its cryptic behavior, it also may be naturally uncommon. As such, even small numbers of kills could have detrimental effects on populations. Some individuals are known to be taken as direct catch in drives in the Caribbean Sea and offJapan, Indonesia, Taiwan, and Sri Lanka, either as food or to be used as bait in other fisheries. Incidental catches of the Pygmy Killer Whale have been reported throughoutits distribution, in gillnets especially, but poor monitoring means these reports likely underestimate numbers of individuals taken. The Pygmy Killer Whale is also vulnerable to loud underwater sounds generated by military activities and seismic surveying. Naval exercises off Taiwan in 2004-2005, for example, coincided with several stranding events of cetaceans, one of which included a Pygmy Killer Whale with acoustic-related injuries. Only a few individuals have been held in captivity, and most of them have behaved aggressively.
Bibliography. Donahue & Perryman (2009), Jefferson et al. (2008), Madsen et al. (2004), Mignucci-Giannoni et al. (2000), Ross & Leatherwood (1994), dos Santos & Haimovici (2001), Taylor et al. (2008c), Wang & Yang Shihchu (2006, 2007).
description: Published as part of Russell A. Mittermeier & Don E. Wilson, 2014, Delphinidae, pp. 410-526 in Handbook of the Mammals of the World – Volume 4 Sea Mammals, Barcelona :Lynx Edicions on pages 518-519, DOI: 10.5281/zenodo.6610922