The sperm whale is the largest toothed whale. Males reach 60 feet (17 m) in length and the smaller females are 37 feet (12 m). They are dark gray in color, have a hump rather than a dorsal fin, and usually display their tail flukes when they dive. Their skin is wrinkled to increase surface area for heat loss, giving them a shriveled look. Their heads make up one-third of their body length and are squarish in shape. They have a single, S-shaped blowhole located far forward and to the left of their head, which produces a distinctive angled spout or blow. Males have about 40-50 teeth, located only in their narrow lower jaw; females have even fewer teeth.
Sperm whales live in every ocean in the world but stay away from the extremely cold waters near the polar ice in the north and the south. Females usually remain in temperate and tropical waters within 45-55° latitude, whereas males travel in temperate waters. Sperm whales prefer deep water around ocean trenches, where strong currents flow in opposite directions bringing concentrated nutrients to the area, and attracting a large number of creatures that the sperm whales can eat. In California, sperm whales can be seen in waters off the continental slope from November to April.
Mating occurs in spring and summer, and males may battle for herds of females. Females carry their young for 14-16 months, and calves are 13 feet (4 m) long and weigh about a ton (1,000 kg) when born. They nurse for two years, but may continue nursing intermittently for up to eight years! Females give birth every three to five years. Young adult males will leave female-led pods and form bachelor herds until they are able to compete in mating (at about 20 years old). Adult males lead a solitary life except for the breeding season.
Female and young male sperm whales are social and sometimes are seen in pods, or groups, of up to 50 whales. The females form matriarchal pods while the males form bachelor herds. Sperm whales are champion divers and are thought to dive to depths greater than 3,000 feet (1,000 m) and stay under water for up to two hours! Just as amazingly, they get to these depths in a matter of minutes. Squid is their favorite food, and they probably spend a lot of their diving time hunting for prey using echolocation. Sperm whales also produce a series of clicks called "codas." Each whale has a distinctive coda and scientists think that other sperm whales recognize each other by their codas. There is also evidence that they produce intense bursts of sound to stun their prey. The sperm whale is a species that is known to strand in large groups. It is not known why they strand (which means certain death), but some theories include illness, parasitic infection, following sick leaders, and malfunction of echolocation due to gently sloping beaches and underwater magnetic anomalies, which leads to disorientation.
Sperm whales were hunted in the past for spermaceti oil, found only in the head of sperm whales and used in echolocation. They were also hunted for ambergris, a waxy substance that forms around squid beaks in the digestive system. Ambergris was used in making perfume. Today sperm whales are protected, and the population is close to 360,000, with 2,800 found in California waters.
At The Marine Mammal Center