Sperm Whale

Physeter macrocephalus

Sperm Whale (Physeter macrocephalus) is a species in the genus Physeter, family Physeteridae, order Artiodactyla.

Scientific classification

Description

The sperm whale is the largest toothed predator alive. Bulls reach about 16 metres and 40 tonnes, females considerably less — the most pronounced sexual size dimorphism of any cetacean. The head makes up roughly a third of the body and houses the spermaceti organ, a mass of waxy oil that gives the animal its name and was the reason for its industrial slaughter.

The brain is the largest of any animal that has ever lived, at about 7–8 kilograms.

Diving and echolocation

Sperm whales routinely dive beyond 1,000 metres for an hour or more in pursuit of deep-water squid, including the giant squid Architeuthis; sucker scars on their heads are the most familiar evidence of these encounters. They produce the loudest sounds of any animal — directional clicks in excess of 230 decibels — generated in the nasal complex and focused forward through the spermaceti organ.

Social structure

Females and young live in stable matrilineal units that persist for decades and share calf-minding. Units belong to larger "clans" distinguished by their patterns of repeated clicks, called codas. Because coda repertoires are learned rather than inherited and differ between sympatric clans, they are among the strongest candidates for culture in a non-human animal.

Males leave their natal unit in adolescence and range to high latitudes alone.

Conservation

Vulnerable. Commercial whaling removed a very large fraction of the population before protection; current threats include ship strikes, entanglement, and ingestion of plastic debris.

References

• Whitehead, H. (2003). Sperm Whales: Social Evolution in the Ocean.
• Taylor, B. L. et al. (2019). Physeter macrocephalus. IUCN Red List assessment 41755.