Sperm whale, Physeter macrocephalus

Detailed introduction

The sperm whale ( Physeter macrocephalus ) is the largest living toothed whale and one of the largest predators in the ocean, belonging to the family Physeteridae . Its massive, square head accounts for more than one-third of its body length and contains a highly developed spermaceti organ , used for sonar production and buoyancy regulation. Sperm whales are renowned deep-diving squid hunters , often diving to depths of 800–1200 meters (with extreme depths exceeding 2000 meters), and single dives can last 45–60 minutes or even longer. The IUCN classifies it as Vulnerable (VU) .

Ecology and Behavior

They primarily feed on medium to large cephalopods (squid, octopus), but also prey on fish. Females and calves form matrilineal family groups , with adult females cooperating in raising the young. Adult males are mostly solitary or live in small groups, migrating to higher latitudes as they age. Acoustically, they emit a series of "clicks" for echolocation and communication; different groups have unique " dialectal " rhythms.

Morphology and Recognition

The body is robust, with a large, square head; the dorsal fin is reduced to a small protrusion, and the posterior part of the back has a wavy ridge; the body color is dark gray to blackish-brown, often with abrasions and circular sucker scars. The lower jaw is slender and has rows of conical teeth (the upper jaw usually has no teeth exposed). The blowhole is located on the left front of the head, and the water jet is a characteristic oblique jet that is low and tilted forward at 15–20° .

Distribution and Habitat

Globally distributed in deep ocean and continental slope/trench waters, commonly found in high-productivity waters near upwelling currents, canyons, and seamounts; adult males are more common in high-latitude waters, while females and calves are more prevalent in tropical to subtropical regions.

Threats and Protection

• Historical whaling impact : Large-scale commercial whaling in the past has led to a significant decline in whaling numbers.

• Fishing gear entanglement and vessel collisions : Longline fishing, drift nets and busy waterways pose risks.

• Underwater noise and blasting/seismic exploration : can interfere with sonar and foraging, and may alter habitat distribution.

• Pollution and ingested debris : persistent organic pollutants, heavy metals, marine debris; ambergris is occasionally found to form in the gut.

• Climate variability and prey variation : Influencing the abundance and distribution of deep-sea cephalopods.

Key measures include: improvement and detour pilot of high-risk fishing gear, speed and route management, marine noise assessment and mitigation, spatiotemporal dynamic protection of important habitats, and transnational collaborative stranding rescue networks and long-term population acoustic monitoring.