Description & Behavior
Dwarf sperm whales, Kogia sima (Owen, 1866), are small rare cetaceans with porpoise-like bodies that measure between 2.1-2.7 m. The blowhole of these whales are found left of the melon and the skull is asymmetrical. Dwarf sperm whales are gray in color with a white ventral side, some with pink or purple blotches. The pectoral fin measures 40 cm high; the tail flukes measure 61 cm. The head measures about 1/6 the length of the body and the facial portion of the skull is the shortest of all cetaceans. Dwarf sperm whales have a mark on either side of the head known as a “false gill” because of its resemblance to the gill slits of fish (which it shares with the closely-related pygmy sperm whales). The dwarf sperm whale has large curved sharp teeth in the lower jaw. Small non-functional teeth may be present in the upper jaw.
Dwarf sperm whales are a gregarious species often found in mixed-sex groups 10 or fewer. They are sluggish animals occasionally seen floating in the water near the shore.
World Range & Habitat
Dwarf sperm whales, Kogia sima, world range is unknown though they are often found in coastal waters near the surface, and they are also known to be deep divers.
Feeding Behavior (Ecology)
Little is known about the reproductive cycle of dwarf sperm whales, Kogia sima. Males and females sexually mature when they reach lengths of 2.1-2.2 m. Gestation is thought to last about 9 months followed by a calving season of 4-5 months. Females are thought to give birth to one calf measuring about 1 m long at birth.
Conservation Status & Comments
The rarity of dwarf sperm whales exclude it from threats due to commercial hunting, however, some scientists theorize that their scarcity may be due to extensive hunting in the past.
Dwarf sperm whales, Kogia sima, are classified as Data Deficient on the IUCN Red List of Threatened Species:
DATA DEFICIENT (DD)
A taxon is Data Deficient when there is inadequate information to make a direct, or indirect, assessment of its risk of extinction based on its distribution and/or population status. A taxon in this category may be well studied, and its biology well known, but appropriate data on abundance and/or distribution are lacking. Data Deficient is therefore not a category of threat. Listing of taxa in this category indicates that more information is required and acknowledges the possibility that future research will show that threatened classification is appropriate. It is important to make positive use of whatever data are available. In many cases great care should be exercised in choosing between DD and a threatened status. If the range of a taxon is suspected to be relatively circumscribed, and a considerable period of time has elapsed since the last record of the taxon, threatened status may well be justified.
References & Further Research
Research Kogia sima @
Barcode of Life ~ BioOne ~ Biodiversity Heritage Library ~ CITES ~ Cornell Macaulay Library ~ Encyclopedia of Life (EOL) ~ ESA Online Journals ~ FishBase ~ Florida Museum of Natural History Ichthyology Department ~ GBIF ~ Google Scholar ~ ITIS ~ IUCN RedList (Threatened Status) ~ Marine Species Identification Portal ~ NCBI (PubMed, GenBank, etc.) ~ Ocean Biogeographic Information System ~ PLOS ~ SIRIS ~ Tree of Life Web Project ~ UNEP-WCMC Species Database ~ WoRMS