Sperm Whale

Description

The sperm whale is the largest of all toothed whales and the largest toothed predator on Earth. Adult males can reach lengths of 52 to 59 feet and weigh up to 45 tons, while females are considerably smaller at 36 to 39 feet and approximately 15 tons. The sperm whale’s most striking feature is its enormous, block-shaped head, which constitutes roughly one-third of its total body length and houses the largest brain of any animal ever known to have existed, weighing up to 20 pounds. The head contains a large reservoir of a waxy substance called spermaceti, which was historically prized by whalers and may function in buoyancy control and sound production. The body is dark brownish-gray with a wrinkled, prune-like skin texture. The blowhole is located on the left side of the head and angled forward, producing a distinctive bushy blow that projects forward and to the left at about a 45-degree angle. The lower jaw is narrow and underslung, containing 20 to 26 pairs of large conical teeth that fit into sockets in the upper jaw.

Habitat & Range

Sperm whales are found in all of the world’s deep oceans, from the equator to the edges of polar ice. They are predominantly a deep-water, offshore species, preferring areas where the continental shelf drops off into deeper waters, typically over 3,000 feet deep. In the eastern North Pacific, sperm whales range from the Gulf of Alaska to the equator. The deep submarine canyons and basins off the Southern California coast, including areas accessible from Orange County, provide suitable habitat, though they are more commonly encountered further offshore than many other cetacean species seen on coastal whale-watch trips. Males undertake extensive migrations between high-latitude feeding grounds and tropical breeding areas, while females and young generally remain in warmer temperate and tropical waters year-round. Social groups of females and young are most common in lower latitudes, while solitary mature males may range into higher latitudes to feed.

Diet

Sperm whales feed primarily on medium to large squid, including deep-water species and occasionally giant squid and colossal squid. They also consume octopus, various species of deep-water fish including sharks and rays, and other cephalopods. An adult sperm whale may consume approximately 2,000 pounds of food per day. To reach their prey, sperm whales are among the deepest and longest-diving of all marine mammals, routinely diving to depths of 1,000 to 2,000 meters and remaining submerged for 45 minutes to over an hour. Some dives have been recorded to depths exceeding 3,000 meters. During these deep foraging dives, sperm whales use powerful biosonar clicks to locate prey in the pitch-dark deep ocean. The clicks they produce for echolocation are the loudest sounds made by any animal, measured at over 230 decibels. Circular scars from squid suckers found on the skin of many sperm whales provide evidence of encounters with large, deep-dwelling cephalopods.

Behavior

Sperm whales are highly social animals with complex social structures. Females and their offspring live in stable family groups of 10 to 20 individuals, often accompanied by related females spanning multiple generations. These groups engage in communal calf care, with members taking turns watching over calves near the surface while others dive to feed. Mature males leave their natal groups as adolescents and may form loose bachelor groups before becoming increasingly solitary as adults. Large males visit female groups during the breeding season. Sperm whales communicate using patterns of clicks called codas, which vary between social groups and geographic regions, functioning much like dialects. They rest vertically near the surface in a behavior sometimes called “logging.” When threatened, sperm whales may form a defensive formation called a “marguerite,” with their heads together and tails facing outward. Females give birth to a single calf every four to six years after a gestation period of 14 to 16 months, one of the longest in the animal kingdom.

Conservation Status

Sperm whales are listed as Vulnerable on the IUCN Red List and as Endangered under the U.S. Endangered Species Act. Commercial sperm whaling, which began in the early 18th century and intensified dramatically in the 19th and 20th centuries, killed an estimated one million or more sperm whales worldwide. The species was heavily targeted for spermaceti oil, used in lamps, lubricants, and candles, as well as ambergris, a waxy substance produced in their intestines that was highly valued in the perfume industry. Since the IWC moratorium on commercial whaling in 1986, populations have been slowly recovering. The current global population is estimated at approximately 300,000 to 450,000 individuals. Modern threats include entanglement in deep-water fishing gear, ingestion of marine debris (particularly plastic), ship strikes, underwater noise pollution that may interfere with their echolocation and communication, and bioaccumulation of toxins in their tissues. Climate change may also alter the distribution and abundance of their deep-water prey.