Pygmy Sperm Whale (Kogia breviceps)

Pygmy Sperm Whale
(Kogia breviceps)
Photo: NOAA

Did You Know?

· Pygmy sperm whales live in tropical and temperate latitudes throughout the ocean, except the Arctic.

· They have a bracket-shaped marking behind the eye, often called a "false gill."

· They often lie motionless at the surface with the back of the head above the water.

Similar to squids, pygmy sperm whales use an ink-like liquid to evade and deter predators.
In 1966, a scientist at the Smithsonian Institution determined that the pygmy and dwarf sperm whales were actually two separate species in the family Kogiidae.

Status
MMPA - Pygmy sperm whales, like all marine mammals, are protected under the MMPA.

Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Cetacea
Family: Kogiidae
Genus: Kogia
Species: breviceps

Species Description
tPygmy sperm whales are small members of the toothed whale group, and one of two species in the family Kogiidae. They reach lengths of up to about 11.5 ft (3.5 m) and weigh between 700-1,000 lbs (315-450 kg). Much of the information on distribution and biology is based upon "stranding" records for this species.

This species has a small, compact body that tapers near the tail and has a small, low, rounded, "dorsal" fin. The shape of the dorsal fin varies depending on the individual. The head is sometime described as "shark-like" due to a conical, pointed snout, and a small narrow, distinctive, underslung lower jaw. Unlike dwarf sperm whales, this species does not have irregular grooves or creases on the throat. Pygmy sperm whales lack teeth in their upper jaw, but have 10-16 pairs of teeth in the lower jaw that fit into sockets in the upper jaw. Their "bulging" eyes are dark with a light circular mark above and around them. Behind the eye is a pale false gill plate, which looks similar to a fish's gill cover. Like their larger cousin the sperm whale, pygmy sperm whales have a "spermaceti" organ and single blowhole situated slightly to the left side of the body. While on the surface, they have a low profile due to the level position of the head and back. The skin is wrinkled (only when closely observed) and has a brownish to dark bluish-gray coloration on the dorsal side. The ventral side is paler with whitish to pinkish coloration that gives the animal a counter-shading effect.

This species is frequently seen at the surface either alone or in small groups of up to 6-7 animals. These groups can vary/mix based on age and sex, but little else is known about their social organization. Pygmy sperm whales are rarely active or aerial at the surface, and it is very uncommon for them to approach boats. Usually they are seen slowly swimming (3 knots) or "logging" at the surface, showing only a small portion of their body. Before diving, they will slowly roll or sink and disappear from view without displaying their flukes. This species is very difficult to observe at sea given their timid behavior, lack of a visible blow, and low profile/appearance in the water. They are usually only detected in ideal sea state (calm) and weather conditions (low wind speeds and little or no swells).

The dwarf sperm whale is another species that appears very similar to the pygmy sperm whale. The two species differ slightly in physical size (pygmy sperm whale being slightly larger), morphology, and other minor features. Compared to dwarf sperm whales, pygmy sperm whales have a flatter profile on the surface, a blunt squarish head, and a distinctive curving hump on the rear portion of the back. As the animal ages, the head becomes blunter and more squarish. The geographic distribution and range for these species may overlap in some areas. In the wild, it is very difficult to distinguish between the two species because of these similarities. Both species are poorly known and are considered "rare."

An unusual characteristic that distinguishes pygmy and dwarf sperm whales from other cetacean species is the use of the "squid tactic." In the lower portion of the intestine, each species has a sac filled with liquid. These animals are capable of ejecting up to 13 quarts (12 liters) of viscous, dark reddish-brown liquid when they feel threatened or when trying to evade predators. Similar to squid and other cephalopod species, the "ink" creates a dense cloud that may discourage predators and/or functions as a confusing diversion allowing the whale to escape (Reeves et al. 2002).

Pygmy sperm whales are probably capable of diving to at least 1000 ft (300 m) in search of food. They also probably use echolocation to locate prey. Their diet consists of cephalopods (e.g., squid and octopus), crustaceans (e.g., crabs and shrimp), and fish. Based on the structure of their lower jaw and analysis of stomach contents, these animals forage and feed in mostly mid- and deep water environments, as well as near the ocean bottom. They may feed in slightly deeper waters than dwarf sperm whales.

Pygmy sperm whales become sexually mature at 4-5 years of age. Gestation in these cetaceans is probably about 9-11 months. The mating and calving season lasts about nine months, and peaks from March-August in the Northern Hemisphere. Newborn calves are about 3.9 ft (1.2 m) in length and weigh 110 lbs (50 kg), and are probably weaned after a year. Females may also give birth to a calf in consecutive years. The estimated lifespan for this species may be up to 23 years.

Habitat
Pygmy sperm whales prefer tropical, subtropical, and temperate waters in oceans and seas worldwide. They are most common along the waters seaward of the continental shelf edge and the slope; and in most areas are thought to be more "oceanic" and "anti-tropical" than dwarf sperm whales.

Pygmy Sperm Whale Range Map
(click for larger view PDF)

Distribution
Pygmy sperm whales have a cosmopolitan distribution in temperate and tropical seas worldwide. In the Southern Hemisphere, their range includes Chile, South Africa, the Tasman Sea, and Uruguay. In the Northern Hemisphere, their range includes the Netherlands, northwestern Europe, the Azores, Nova Scotia, Washington, Hawaii, and Japan. Kogia (the genus that both pygmy and dwarf sperm whales belong to) may be more common off the coasts of the southeastern United States and South Africa based on the records of higher numbers of "stranding events" in these areas. The seasonality and migration patterns of this species are unknown.

Population Trends
For management purposes, pygmy sperm whales inhabiting U.S. waters have been divided into four stocks: the California/Oregon/Washington stock, the Hawaiian stock, the Northern Gulf of Mexico stock, and the Western North Atlantic stock. The estimated abundance for Kogia sp. (pygmy and dwarf combined) is 250-400 for the Western North Atlantic stock, and 550-750 for the Northern Gulf of Mexico stock. The estimated abundance for pygmy sperm whales in the Hawaiian Islands EEZ is 4,000-7,500 and for the California/Oregon/Washington stock is 100-250 animals. There are insufficient data for this species to determine the population trends.

Threats
Pygmy sperm whales are incidentally taken as bycatch in fishing gear that includes driftnets, gillnets and purse seine operations. This species was killed occasionally by hunters targeting sperm whales during the 19 th century and have been recently taken in commercial harpoon fisheries in Indonesia, the Lesser Antilles, and Japan. Due to their behavior of logging motionless on the sea surface, they are occasionally subject to ship strikes. Some stranded whales have been documented with plastics and other garbage blocking their guts. Stranded specimens have also been documented with degenerative heart disease, immune system problems and heavy parasite infestations. This species of whale may be sensitive to underwater sounds and anthropogenic noise. Anthropogenic noise levels in the world's oceans are an increasing habitat concern, particularly for deep-diving cetaceans like pygmy sperm whales that use sound to feed, communicate, and navigate in the ocean.

Conservation Efforts
The IUCN Red List of Threatened Species considers this species "Lower Risk Least Concern."

Regulatory Overview
This species is protected under the Marine Mammal Protection Act of 1972, as amended.

Key Documents
(All documents are in PDF format.)

Title	Federal Register	Date
Stock Assessment Reports	n/a	various

More Information

References:

Jefferson, T. A, M. A. Webber, and R. L. Pitman. (2008). Marine Mammals of the World, A Comprehensive Guide to their Identification. Amsterdam, Elsevier. p. 79-81.
Reeves, R. R., P. A. Folkens, et al. (2002). Guide to Marine Mammals of the World. New York, Alfred A. Knopf. p. 244-247.
Shirihai, H. and B. Jarrett (2006). Whales, Dolphins and Other Marine Mammals of the World. Princeton, Princeton University Press. p.148-150.