Pygmy sperm whale - Kogia breviceps

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Pygmy sperm whales are very difficult to detect, except in extremely calm seas. They have a shark-like head with a narrow underslung lower jaw. The flippers are set high on the sides near the head. The small sickle-shaped dorsal fin is usually set well behind the midpoint of the back and the blowhole is positioned more than 10% of the way down the back from the snout tip. Pygmy sperm whales are countershaded, ranging from dark gray on the back to white below. Often the belly has a pinkish tone. There is a light colored bracket mark, dubbed the "false gill," along the side between the eye and the flipper. The lower jaw generally contains 12-16 pairs of long, fang-like teeth that fit into sockets in the upper jaw, which usually has no teeth.

Adult pygmy sperm whales are 2.7-3.8 m long, and newborns are about 1.2 m. Adults may weigh as much as 450 kg.

Pygmy and dwarf sperm whales can be somewhat difficult to distinguish at sea. Pygmy sperm whales grow to somewhat greater lengths, and have smaller, more rounded dorsal fins, generally set farther back on the body. The position of the blowhole is another good indicator (more than 10% of the way back from the snout tip in pygmy sperm whales). There is some degree of overlap in most characteristics of these two species, and identifications must be made cautiously, even with a specimen “in hand.”

Pygmy sperm whales are found in deep waters in tropical to warm temperate zones of all oceans. They appear to be especially common over and near the continental slope.

Pygmy sperm whales inhabit oceanic waters. Most sightings of pygmy sperm whales are of small groups of less than five or six individuals. Almost nothing is known of the behavior and ecology of this species, other than what has been learned from brief sightings during research cruises. They are generally not commonly seen alive at sea, but they are among the most frequently stranded small whales in some areas. When seen at sea, they have usually appeared slow and sluggish, and often float at the surface with no visible blow. Very little is known of the reproductive biology of the pygmy sperm whale.

Pygmy sperm whale diet is dominated by cephalopods.

Studies of feeding habits, based on stomach contents of stranded animals, suggest that this species feeds in deep water on cephalopods and, less often, on deep-sea fishes and shrimps. Pygmy sperm whales feed by seizing prey.

Known cephalopod prey species include: Heteroteuthis dispar, Lycoteuthis lorigera, Abralia sp., Octopoteuthis sp., Moroteuthis sp., Histioteuthis sp., Illex argentinus, Ornithoteuthis antillarum, Chiroteuthis veranyi, Onychoteuthis banksi, Chiroteuthis sp., Lepidoteuthis grimaldii, Histioteuthis hoylei, Cycloteuthis sirventi, Gonatus steenstrupi, Taonius pavo, Histioteuthis meleagroteuthis, Histioteuthis corona corona

Main threats to pygmy sperm whales include:

• Harvest

• Fisheries bycatch

• Plastic pollution

The pygmy sperm whale is not listed as threatened or endangered by either the IUCN or the United States government. Although they have never been taken in large numbers, either directly or incidentally in fisheries, pygmy sperm whales have been occasional victims of dolphin and small whale fisheries, as well as gillnet and purse seine operations. Other potential threats include plastic ingestion (as associated gut-blockage) and ship strikes.

The United States National Marine Fisheries Service considers animals in United States waters to be members of several distinct stocks, and assesses them separately. Delineations between stocks are often difficult to determine, therefore assessments should be considered ongoing processes. In the case of the pygmy sperm whale, concern that sightings may be confused with the cogener K. sima (the dwarf sperm whale) further complicates the estimation of abundance. Stocks are estimated as follows

California/Oregon/Washington stock – 4,746 (CV = 0.67) 1991, 1993, and 1996 surveys

All Kogia sp. (K. breviceps and K. sima) in the northern Gulf of Mexico – 547 (CV = 0.28) 1991-1994 shipboard surveys

All Kogia sp. in the western North Atlantic stock – 536 (CV = 0.45) 1998 shipboard and aerial surveys

• iOBIS
• World Register of Marine Species (WoRMS)
• Encyclopedia of Life
• Catalog of Life
• Integrated Taxonomic Information System (ITIS)
• Barcode of Life

Baird, R.W., D. Nelson, J. Lien and D.W. Nagorsen. 1996. Status of the pygmy sperm whale, Kogia breviceps, in Canada. Canadian Field-Naturalist 110:525-532.

Caldwell, D.K. and M.C. Caldwell. 1989. Pygmy sperm whale Kogia breviceps (de Blainville, 1838) Dwarf sperm whale Kogia simus Owen, 1866. pp. 234-260 in S.H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Vol. 4: River dolphins and the larger toothed whales. Academic Press.

Dos Santos, R.A. and M. Haimovici. 2001. Cephalopods in the diet of marine mammals stranded or incidentally caught along southeastern and southern Brazil (21-34° S). Fisheries Research 52:99-112.

McAlpine, D.F. 2002. Pygmy and dwarf sperm whales Kogia breviceps and K. simus. pp. 1007-1009 in W.F. Perrin, B. Würsig and J.G.M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.

McAlpine, D.F., L.D. Murison and E.P. Hoberg. New records for the pygmy sperm whale, Kogia breviceps (Physeteridae) from Atlantic Canada with notes on diet and parasites. Marine Mammal Science 13:701-704.

Ross, G.J.B. 1979. Records of pygmy and dwarf sperm whales, genus Kogia, from southern Africa, with biological notes and some comparisons. Annals of the Cape Provincial Museums (Natural History) 15:259-327.

Scott, M.D., A.A. Hohn, A.J. Westgate, J.R. Nicolas, B.R. Whitaker and W.B. Campbell. 2001. A note on the release and tracking of a rehabilitated pygmy sperm whale (Kogia breviceps). Journal of Cetacean Research and Management 3:87-94.