Sperm whale (Physeter macrocephalus)

Anatomy and adaptations

Sperm whales have a massive, oil-filled head and a relatively narrow lower jaw lined with large, conical teeth. Those teeth fit into sockets in the roof of the mouth, a detail sometimes noted in anatomical descriptions (lower jaw teeth and sockets). The spermaceti organ—a large structure of waxy oil and other tissues—occupies much of the head and is associated with powerful, focused clicks used for echolocation. Thick blubber, sturdy bodies, and robust lungs support long, deep dives.

Behavior and ecology

These whales are accomplished deep divers that hunt at great depths for squid and other prey. They employ loud, patterned clicking sounds both to navigate in darkness and to locate prey. Social structure is complex: females and young typically form stable matrilineal groups, while mature males may lead more solitary lives or gather in loose bachelor groups. Sperm whales communicate with series of clicks called codas, which vary between groups and populations.

Range, diet and life history

Sperm whales inhabit oceanic waters across temperate and tropical regions. Their diet is dominated by cephalopods, including large squid, but they will also eat fish and other deep-water organisms. Calves are raised within family groups; adult females and younger animals cooperate in caring for young. Growth is slow and populations recover slowly from large losses.

Human interactions and conservation

Historically, sperm whales were heavily hunted for spermaceti oil and ambergris, materials prized for lighting, lubrication and perfumery, which drove dramatic population declines in the 18th and 19th centuries. Today they are protected in many regions, but threats remain from ship strikes, entanglement, noise pollution, and the long-term effects of historical whaling. Conservation assessments list sperm whales as at risk in parts of their range, and international efforts monitor populations and mitigate human impacts.

Notable facts

• They are the largest toothed whales and possess the largest brain of any known animal.
• The spermaceti organ contributes to their unique silhouette and sophisticated acoustic abilities.
• Ambergris, a rare digestive by-product once highly valued, is associated with sperm whales.

Understanding of sperm whale biology has advanced through a mix of historical records, modern observation, acoustic studies and tagging, but many aspects of deep-water behavior and population structure continue to be active areas of research.