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FALSE KILLER WHALE
Pseudorca crassidens (Owen 1846)

Order Cetacea : Family Delphinidae

DESCRIPTION. A small, entirely black delphinid; no beak, the head slopes gradually from tip of snout to the blowhole; dorsal fin small, narrow, placed slightly forward of midpoint of the back and directed backward; pectoral fins small, about one-eighth of total length and tapering; teeth large, conical, elliptical in cross section, 15–25 mm in diameter, the largest ones projecting 30 mm or so above the gums (40 mm above jawbone), and numbering 8–11 in each tooth row. Adult males reach a length of 5.7 m; females, 4.9 m. Superficially resembles the short-finned pilot whale (Globicephala macrorhynchus) but lacks the bulbous forehead and the teeth are nearly twice as large.

Pseudorca crassidens

DISTRIBUTION. False killer whales are distributed worldwide in tropical and temperate waters, and there have been numerous strandings and sightings in the Gulf of Mexico, including a few strandings from the upper Texas coast.

SUBSPECIES. Monotypic species.

HABITS. Groups of these whales may number from two to several hundred, with both sexes and all age groups represented. These delphinids are known to emit whistling sounds audible to humans and probably are good echolocators. They eat squid and fish.

For unknown reasons, false killer whales often strand, sometimes en masse. There are three known mass strandings of these whales in the Gulf of Mexico, but the best known such stranding occurred on the Atlantic coast of southern Florida. On 11 January 1970, 150–175 false killer whales beached themselves and refused to return seaward, despite the best efforts of volunteers. All of the whales subsequently died, and the cause of this mysterious event was never determined.

Their reproductive habits are poorly known. Breeding probably occurs year-round, and the gestation period lasts approximately 15 months. Newborn false killer whales are about 1.5 m in length and weigh 80 kg.

POPULATION STATUS. Uncommon; strandings and observations. There have been 14 strandings and 16 sightings of false killer whales from the northern Gulf of Mexico. Virtually nothing is known about its population abundance and status but five groups were sighted by ship and three by airplane during the GulfCet surveys. Group sizes ranged from 12 to 63, and sightings were in deep water generally 200 to >2,000 m (656–6,562 ft.) deep.

CONSERVATION STATUS. The false killer whale is listed as endangered by the USFWS and threatened by TPWD. The IUCN status is "data deficient" because global trend or abundance data are unavailable. Potential threats to the species include high levels of noise, especially military sonar and seismic surveys, and fisheries bycatch.

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From The Mammals of Texas, Seventh Edition by David J. Schmidly and Robert D. Bradley, copyright © 1994, 2004, 2016.  Courtesy of the University of Texas Press.

Natural Science Research Laboratory