SPERM WHALE

What is should I know about sperm whales?

Sperm whales are divided into Northern and Southern hemisphere populations, and can be found in all oceans. Males range from equator to polar regions, while females and juveniles migrate north too although they usually spend more time in temperate regions.

How many sperm whales are there?

Sperm whales are considered endangered according to the U.S. Endangered Species Act. Sperm whale populations are difficult to estimate, mostly due their capacity to remain submerged for long periods.

If you would like to read more about sperm whale stocks, NMML's 1998 Alaska Stock Assessment (in PDF format) discusses the North Pacific stock. Also, the Southwest Fisheries Science Center's 1996 Stock Assessments are avaible discussing the sperm whale California/Oregon/Washington Stock.

How can I identify a sperm whale?

Male sperm whales grow to about 60 feet (18.3 meters) while female sperm whales grow to approximately 43 feet (13.1 meters) long. Male and female sperm whales have huge, squarish foreheads, small inconspicuous eyes, and a long narrow lower jaw. Sperm whales have one blowhole located at the left of the forehead. Their blows are projected forward at an angle, which is very different from other whales. Their light-brown to blue-gray skin is rippled over much of the body, especially on the back and sides.

How well can a sperm whale see or hear?

Sperm whales have disproportionately small eyes so it is thought that they do not see particularly well. In fact, blind sperm whales have been captured in perfect health with food in their stomachs. Instead of sight, sperm whales are thought to use echolocation to seek their prey and navigate the topography of their environment. Sperm whale hearing abilities are not well known.

What do sperm whales eat?

Sperm whales are among the deepest marine mammal divers. Males have been known to dive 3,936 feet (1199.7 meters) while females dive to at least 3,280 feet (999.7 meters). Sperm whales can dive for over an hour. Giant squid comprise about 80% of the sperm whale diet and the remaining 20% is comprised of octopus, fish, shrimp, crab and even small bottom-living sharks. Sometimes getting a meal isn't easy for sperm whales as evidenced by disk-shaped scars and wounds likely made by giant squid resisting capture.

How do sperm whales have their young?

Sperm whale herds appear to be organized on a "harem" system similar to elephants where a solitary bull (male) sperm whale joins a school of 10-40 adult females plus their calves, and juveniles (of both sexes) for the length of a breeding season. Males sometimes fight to gain control of harems by biting and butting of other males. Females will sometimes assist this process by driving away older males.

Breeding seasons occur in the middle of summer according to hemisphere and 12-13 foot calves are born after a 14-16 month gestation period. Females nurse their calves for two years and longer suggesting that nursing is both a social and a feeding function for sperm whales. Females are able to conceive at about 28 feet (8.5 meters) long, while male sperm whales are probably not able to mate until they are 39 feet (11.9 meters) long.

How long do sperm whales live? How do they die?

Sperm whales may live to be 50-70 years of age. Sperm whales die of natural causes, have been known to mass strand, and were the focus of a commercial hunt in the 18th and 19th centuries. They were sought for their special spermaceti oil (which even today is used as a high grade lubricant), their blubber which makes an excellent oil, and their meat (which apparently tastes better than chicken!). The famous literary classic, Moby Dick tells the story of a 19th century whale hunt.

Where can I find more information about sperm whales?

Books and the world wide web are excellent places to learn more about marine mammals.

Books

Leatherwood, Stephen. Reeves, Randall R. Foster, Larry. The Sierra Handbook of Whales and Dolphins. Sierra Club, San Francisco, CA. 1983.
Leatherwood, Stephen. Reeves, Randall R. Perrin, William F. Evans, William E. Whales, Dolphins, and Porpoises of the Eastern North Pacific and Adjacent Arctic waters; A Guide to their Identification. Dover Publications, Inc., New York, NY. 1988.
Wynne, Kate. Folkens, Pieter. Guide to Marine Mammals of Alaska. Alaska Sea Grant Program. University of Alaska Fairbanks, Fairbanks, AK. 1992.

World Wide Web

Alaska Stock Assessment Reports. 1996. Draft 1998.
Pacific Marine Mammal Stock Assessment. 1996.
The Whale Center of New England. http://www.whalecenter.org.
The National Aquarium in Balitmore's Animals Section. http://www.aqua.org/animals/.
The Whale Museum at Friday Harbor, Washington. http://www.whale-museum.org/.
The Whalenet. http://whale.wheelock.edu/.

There are many more sources to learn about cetaceans. Check with NMML's online library or your local librarian for her or his recomendations.

In a taxonomic sense, where do sperm whales fit into the picture?

This site was created by Laura Drumm and the National Marine Mammal Laboratory

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