In the animal kingdom it can boast several records. It is the largest toothed predator in the world. And its brain, which can weigh up to eight kilos, is the largest among animals.

On the other hand, that enormous mass is guarded by a gigantic head, up to 5 meters long, corresponding to about a third of the entire body of the giant, justifying the epithet "macrocephalus", which completes the scientific name whose first part, Physeter, identifies the genus of cetaceans of which it is the only remaining representative, as well as of the family of Physeteridae. The most well-known and used common name of Sperm Whale, however, refers to another of its peculiar characteristics: the presence, always in the head, of an oily substance, spermaceti. In the past, it was at the origin of the ruthless hunt that had made it prey in all the seas of the world, before being banned internationally in 1985, forty years ago.

The large marine mammal, which can live up to sixty/seventy years, inhabits the blue planet almost everywhere. Including the Mediterranean, where a specific population lives, reduced in number of specimens, estimated at around 2500, which is therefore considered vulnerable. In particular, sperm whales seem to prefer the western and central part of the basin and are also present in the Italian seas. They live in the Ligurian Sea, where they are among the species protected in the Pelagos Sanctuary; in the gulfs of Gaeta and Naples, between the Pontine and Flegrean Islands; in the Ionian Sea and around Sicily, while in the Adriatic sightings are sporadic. The sperm whale, in fact, needs great depths and frequents coastal areas, even around the islands, only where it finds deep canyons or where the continental shelf drops off abruptly.

Sperm whales, in fact, usually dive beyond five hundred meters and go as far as two thousand meters, being able to also face long apneas, another fundamental peculiarity compared to other marine mammals. If they normally resurface to breathe on average every 45 minutes, they can remain immersed for up to two hours. They also remain apnea during the resting phases, when they position themselves vertically with their large head towards the surface, floating at low depths.

What drives them to the depths of the sea is the search for food. Sperm whales, which are odontocetes, therefore equipped with teeth, feed on cephalopods, in general, and fish, but their diet is mainly composed of giant squids that they find at great depths. There, in the abyss, the cetacean proves to be a very skilled predator, capable of catching even giant squids that can exceed ten meters. From the fights they engage in with their prey, which use their large suckers to defend themselves, some of the signs that remain evident on their bodies for the rest of their lives derive.

The gigantic bodies, which in adult males reach 18 meters and weigh 57 tons and in females 12 meters and 24 tons, are entirely gray with a white part around the mouth. But progressively, as they age, on each body you can distinguish more and more white marks left by the scars caused by prey or by violent fights between males, in which the various specimens use their teeth. Those marks, which make each specimen unique and recognizable, are used by researchers for photo identification, thanks to which census activities, monitoring of movements, and study of social groups are possible. Another identifying element, since it has different characteristics for each individual, is the triangular caudal fin, which the animal takes out of the water before diving back in after breathing for about eight minutes. This is indicated by the characteristic oblique and irregular blow that comes from the blowhole located at the end of the left part of the head.

Sperm whales have a matriarchal social structure with stable groups of about ten females, accompanied by their young and juveniles. When, between 18 and 21 years of age, the males reach sexual maturity, they move away from the maternal group and with other males form bachelor groups that move over very long distances in the oceans, pursuing their prey as far as the cold waters at the edge of the polar zones. The males return to the warmer waters, where the females live permanently with their young, only during the breeding season, in summer, and they stay there only for the time necessary for mating. Sexual maturity for females is between 7 and 13 years; they give birth to a single calf every four/six years, after a gestation period of 14 to 16 months. When it is born, the calf already reaches the remarkable length of almost five meters and weighs 500/800 kilos. Breastfeeding can last from one to three years, even after weaning. To protect their young from danger, the females arrange themselves around them in a peculiar daisy formation, with their large heads (or sometimes tails) facing inwards.

Communication between individuals and within social groups occurs with a very complex system of pulsed sounds, in effect a sonar, which also includes the typical clicks, thanks to which the animals are able to orient themselves even at greater depths, to echolocate and to identify prey and any dangers.

For centuries, especially in the 19th century, sperm whales were hunted everywhere, to extract the oil then used for lamps and producing candles, but also for the ivory of their teeth. With the ban on hunting, having very few natural predators such as killer whales, man with his activities at sea (such as transoceanic cables) remains the main source of risk for the species, assessed as "vulnerable" by the IUCN and the recipient of various protection actions at an international level.