The sperm whale, also called cachalot, is the largest toothed whale and the largest toothed predator on the planet. With a distinctive appearance and block-shaped head, this species is easily recognizable. These whales are cosmopolitan species meaning that they inhabit most waters around the world, from the poles to the equator. The species is the second deepest diving animal, with recorded depths of over 2,000 meters.
The sperm whale, or Physeter macrocephalus, is the sole member of the genus Physeter and the only extant species of the family Physeteridae. Alongside the pygmy whale and dwarf sperm whale, it is member of the superfamily Physeteroidea within the parvorder Odontoceti, or toothed whales along with dolphins and porpoises. The term sperm is not related to its semen, but a cut from the term spermaceti which is a waxy substance found in the animal’s head which is thought to be related either to buoyancy control or echolocation.
Sperm whale anatomy
P. macrocephalus is the largest toothed whales, with male average sizes of 16 to 18 meters. The species present strong sexual dimorphism, meaning that males and females have large
anatomical differences. For example, males can be 30 to 50 percent longer than females and maybe even 3 times as massive. Males have been found to measure 20 meters, with some jawbones found leading scientists to estimate specimens of more than 24 meters long.
The head of the whale is block-shaped and can account for one third to one fourth of the animal’s length. The jawbone is long and has 18 to 24 teeth. Despite being functional, these teeth are thought not to be needed for feeding and are probably used by males when fighting. Adult males can reach weights of over 50 tons. The ribs are connected to the spine by a flexible type of cartilage which allows the animal to dive at great depths.
The sperm whale feeds mostly on squid, but may feed on the larger giant squid or colossal squid as well octopuses or even fish such as rays. Giant squid sucker scars have been found on the skin of cachalots, implying that they may battle these largest invertebrates on occasion. Known as the second deepest diving mammal after Cuvier’s beaked whale, the cachalot can reach depths of 2,200 meters. It has been observed that these animals mostly hunt upside down at greater depths, as they are able to distinguish the silhouettes of squid and other prey. Usually, dives can take as much as an hour, which is more than what most whales can achieve. Cachalots hunt through echolocation.
Reproduction and life cycle
Females reproduce every 4 to 20 years after reaching sexual maturity at 9 years of age. After a 14 to 16 month gestational period females give birth to calves that may suckle for 19 to 42 months. Contrary to most other whales, the calves may be protected and raised for as long as a decade. Females and young males live in pods and protect the weaker sexes while the adult males live separately. It has been estimated that a sperm whale can live for 70 years or more.