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DWARF SPERM WHALE
Kogia sima (Owen 1866)

Order Cetacea : Family Kogiidae

DESCRIPTION. Similar to the pygmy sperm whale (K. breviceps) but smaller (rarely reaching 3 m in length); dorsal fin higher (relatively and actually) and located near center of back; number of teeth in the lower jaw normally 8–11, rarely as many as 13; usually 3 rudimentary teeth in each upper jaw. Total length of adults usually <2.5 m, rarely to 2.7 m. Weight, <300 kg.

Kogia sima

DISTRIBUTION. Like K. breviceps, the dwarf sperm whale is probably cosmo-marine and is found in warm-water oceans. In the western North Atlantic, these whales are known from Virginia to the Lesser Antilles and the Gulf of Mexico. They strand fairly frequently but not as often as K. breviceps. The most recent stranding period (2002–2014) included 10 strandings from six counties along the Texas coast.

SUBSPECIES. Monotypic species.

HABITS. Until the mid-1960s, dwarf sperm whales were routinely grouped with K. breviceps in stranding and sighting reports. As a result, few data are available on the natural history of these whales.

Dwarf sperm whales make deep and prolonged dives in quest of food. Squid and fish are known to be included in the diet. The reproductive habits of K. sima are almost completely unknown. At birth, calves are estimated to be about 1 m in length and 45 kg in weight. The young reach maturity when they are about 2 m in length.

POPULATION STATUS. Uncommon; strandings and observations. Stranding records of dwarf sperm whales from the Gulf of Mexico are more abundant than would be expected for a truly rare animal. This whale occurs about half as frequently as K. breviceps, with strandings throughout the year.

CONSERVATION STATUS. The dwarf sperm whale is listed as threatened by the TPWD, but it is not included on the federal list of concerned species. The IUCN lists it as "data deficient" for the same reason as its sister species, the pygmy sperm whale. Because of the difficulty in distinguishing the two species, virtually nothing is known of its population size in the Gulf of Mexico. Almost all shipboard and aerial sightings are listed as Kogia sp. instead of being either one of the two species.

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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