Marine Animal Encyclopedia
Sperm Whale Physeter macrocephalus
The Latin name for the sperm whale, Physeter macrocephalus, translates to “blower with a big head” which is a pretty accurate description of the species. Their unique block-shaped heads makes the sperm whale easy to identify.
Sperm whales are the largest of all the toothed whales, measuring up to 18m long and weighing in at 60 metric tons. They have tube-shaped bodies, small, paddle-shaped flippers, a small, lumped dorsal fin and large triangular tail flukes.
Most whales have smooth skin, but the sperm whale has wrinkled skin. Sperm whales can be found in every ocean from the Arctic to Antarctica and in most coastal seas and gulfs. They are generally more common in waters greater than 1000m deep, can dive up to 2000 meters deep and can stay down for up to two hours.
Sperm whales also have the biggest brain on the planet and the most powerful natural sonar system which can make sounds louder than a NASA rocket launch. They use this sonar to find squid in the deep ocean and are responsible for removing as much squid in a year as all human fisheries worldwide combined.
Sperm Whale Society
Sperm whale society is matrilineal (grandmothers, mothers, and their daughters live together for life). Sperm whale mothers are pregnant for about 16 months. Calves are born at about 4 meters long and weigh around one ton. Sperm whale calves suckle for at least three years, during which time they do not dive deeply to feed on squid with their mothers. As a result, at least one of the calf's family members remains at the surface to “babysit.” Sexual maturity for both sexes is in their early teens, at which point mature males leave the family unit to travel all over the globe. Adult females have a calf around every four years but are thought to go through menopause in their forties and most individuals can reach as old as 70.
Sperm whales in different parts of the world behave differently because they come from different whale cultures. Although all sperm whales show the same behaviors, they do them differently. A new calf learns its traditional way of doing things from the members of its natal family unit and they will pass on the same way of doing things to their calves in turn. These cultures are marked by different dialects. Just as saying “truck” labels you as North American, but saying “lorry” labels you as from the United Kingdom; sperm whales used different types of social sounds called ‘codas’ in different parts of the ocean. In some parts of the Pacific, there are multicultural areas where several different whale cultures live in the same area and distinct coda dialects overlap.
Sperm Whale Conservation
Sperm whales once numbered in the millions, but the most recent estimate puts the global population of sperm whales at around 360,000 animals. These whales were targeted by Yankee whalers from the east coast of the U.S. during the 18th and 19th centuries. They were killed primarily for the oil in their heads.
Modern hunts, from 1945 to 1984, also focused on sperm whales, particularly in the Pacific. Although the sperm whales are considered protected by the International Whaling Commission and other national and international conservation agreements and legislation, a few sperm whales are still being taken under the auspices of a controversial "scientific" whaling program in Japan.
Outside of whaling, there are still a number of threats including interactions with fisheries, especially with long-line and gillnet fisheries. Since it is a long-lived species, concentrations of PCBs, DDT, and heavy metals are also a concern. Lastly, ocean noise is increasingly garnering attention as a major conservation issue for many cetacean species.
Contribution by Shane Gero
E-mail: [email protected]
What Oceana Does
Oceana works to protect marine mammals, such as sperm whales, from becoming bycatch in commercial fisheries.