Sperm whale

Despite its rare visits to the polar ice latitudes, sperm whales are a globally distributed species that can be found in all of the world’s seas and oceans. Adult males can swim in colder waters, but females live in temperate and tropical climates. They can clearly be found in the Mediterranean Sea, but not in the Black Sea due to the high concentration of sulfides (including hydrogen sulfide) and almost complete absence of oxygen in the water. It is unknown whether sperm whales exist in the Red Sea.

Espaço Talassa in picture

The areas nearest continental shelves are home to the largest populations. Sperm whales were formerly fairly common along the Gulf of Mexico coast, where they are occasionally spotted.

Habitat

Waters as deep as 3,220 meters are home to sperm whales. The time difference needed for the ascent and descent to the surface is most likely the cause of this restriction. These toothed whales’ range is contingent upon the season and their reproductive and social standing, but they are typically found in at least 1,000 meters of water in areas that are squid-inhabited. Sperm whales can really run the risk of running aground when they approach the coast because they are so suited to swimming in deep waters.

Characteristic features

Appearance

The sperm whale’s enormous, up to one-third of its body length, rectangular head, which is broad and blunt at the front, gives it a distinctive appearance that sets it apart from other cetaceans.

Unlike the great majority of cetaceans, the S-shaped blowhole on this animal’s head is on the left side. The caudal fin of the sperm whale is heart-shaped and incredibly thick and wide. The animal gets ready to dive for food by raising its caudal fin far above the water. The caudal fin has numerous longitudinal grooves in its lower portion. Comparing the size of the pectoral fins to the enormous size of the body, they are only 200 cm long. Sperm whales lack a dorsal fin in favor of a low hump.

The subcutaneous fat layer of sperm whales can measure up to 35 cm in thickness.

Coloring

Typically, cetaceans have dark-colored, smooth skin. The sperm whale, on the other hand, is an exception. Its extremely wrinkled skin is a shade of gray or dark graphite, sometimes likened to a prune. It is interesting to note that men frequently become pale and occasionally go bald as they age. The anus, lower jaw, and genital area are light in color in both sexes. Additionally, there is proof that white sperm whales, or albinos, exist.

Large brain and incredible hearing

Of all mammals, sperm whales have the largest brains. It has a volume of roughly 8,000 square centimeters and a maximum weight of 7.8 kg. The brain of a sperm whale is therefore five times heavier than the brain of an adult human. Sperm whales are less intelligent than dolphins, despite the fact that the encephalization coefficient, or EQ, is influenced by brain size.

Their insufficiently developed olfactory system may also be a sign of compromised taste and smell perception. Excellent hearing, however, more than makes up for the lack of these senses.

Spermaceti

Whale Watch Kaikoura, in picture

A sizable set of organs filled with liquid substances that solidify when in contact with the atmosphere are located in the upper region of the whale’s skull. We refer to this material as spermaceti. Though its exact role is unknown, scientists think that this fluid’s and the organ system’s overall primary function is to generate strong, focused sound waves that are used for communication and echolocation.

The melon, which generates spermaceti, is the organ that controls the toothed whale’s buoyancy. The sperm whale can dive deeper by altering the liquid’s state.

Size

The sperm whale has a maximum length of 16–19 meters. The longest specimen found measured 20.5 meters. These statistics are for male sperm whales who are sexually mature. Females typically measure no more than 13 meters, making them roughly one-third smaller. Newborns typically measure about 4 meters in size.

The heaviest individuals can weigh up to 75 tons for men, while women can only weigh 14 tons. Newborns weigh roughly 1/25 of what adult females weigh.

Vocalizations

The sperm whale uses its phonic lips—located at the front of the nose, below the nasal opening—to blow air through them in a specific direction when it uses echolocation. The sounds pass through the melon and back along the nose. The frontal sac, which is part of the whale’s skull, reflects the majority of the signal and concentrates the sound. After that, the sound exits the melon and returns to the area of the nose. It takes only a few milliseconds to complete the process.

Researchers can determine the size of the sperm whale’s melon by listening to the sound it makes. Every whale has a distinct "tone." As it gets older and its melon grows, this changes. The sounds are transmitted to the inner ear via a canal filled with spermaceti. The sperm whale makes noises while submerged because the air inside its head is always vibrating. Four categories of sounds exist:

• a regular click;
• a squeal;
• "knock";
• wheeze.

When a whale encounters another sperm whale, it also emits the conventional repeating sequence of three to forty clicks or more.

The loudest animal on Earth is the sperm whale. It is capable of producing noises up to 230 decibels (dB). A nuclear explosion is approximately 220 dB in volume, while a launch jet is 140 dB. With underwater listening equipment, sperm whale voices can be heard from great distances—many kilometers.

Scuba diving

The sperm whale is the deepest diver among all marine mammals, with the exception of the southern elephant seal (Mirounga) and the northern bottlenose whale (Hyperoodon). It has the ability to descend three kilometers and remain there for up to ninety minutes. On the other hand, the sperm whale typically descends to a depth of 400 meters and remains submerged for approximately 35 minutes.

This enormous cetacean mammal’s elastic chest, which permits the lungs to "squeeze," slows the metabolism and conserves oxygen, allows it to adapt flawlessly to abrupt changes in pressure during diving. The sperm whale takes 8-minute breaks to breathe 20–70 times above the water’s surface in between deep dives.

Image courtesy of Whale Express

Sperm whales can swim up to 30 km/h when disturbed, but they typically only reach speeds of 10 km/h.

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Social structure

Sperm whales travel, but they stay with the same groups for a long time. It is very uncommon for new members to enter a fixed group or for "old" members to depart from it. A single group of toothed whales typically consists of six to nine individuals, though larger groups of more than twenty have been seen.

Groups typically comprise of sexually mature females and their immature offspring of both sexes, or bachelor males, who are inactive in the sexual sense. Male adults live alone, with the exception of mating season. Males are more likely to live alone as they get older.

Unlike killer whales, which frequently copulate, related sperm whales do not copulate. The remaining three-quarters of the lives of females and young are spent hunting; the remainder is spent interacting with others. Most social "rituals" happen in the afternoon.

Eating habits

The sperm whale hunts two kinds of squid: giant squid (Architeuthis dux) and colossal squid (Mesonychoteuthis hamiltoni). This feeding behavior is related to its diet. These two mollusks are the biggest in the world at the same time. Giant squids have a maximum weight of 500 kg and a maximum length of 10 meters. The enormous squid weighs 275 kg and reaches a length of 13 meters.

Furthermore, sperm whales pursue:

• octopuses;
• deep-sea fish;
• sharks;
• seahorses.

Approximately 3% of their body weight is consumed daily by sperm whales. They have the biggest esophagus of any cetacean—in fact, it’s the only one big enough to fit a human inside.

The jaw of sperm whales is long and narrow. There are 18–26 teeth on each side of the lower jaw, but the upper teeth are few, feeble, and non-functional. The lower jaw’s cone-shaped teeth slide into the upper jaw’s sockets with perfect fit.

Pictured by Klaus Rudloff

Nonetheless, it has been demonstrated that sperm whales can hunt effectively even in the absence of teeth. It seems that the more likely explanation for the existence of such teeth is fights between males. Elderly people are covered in many scars that look like sperm whale bite marks.

Breeding season and development of young

Breeding "harems" are formed during the breeding season, with 1–5 large males and a mixed group of females and males of varying ages. There is intense competition between males for females during this time. Of the population’s sexually mature males, only roughly 10–25% are able to procreate.

There is still much to learn about the mating process. There is proof of a male hierarchy, but it’s not clear if the female has the same partner selection options as humpback whales. Males don’t show any interest in their young after birth.

A single calf is born at the end of a 15–18 month gestation period. Women give birth every few years on average. The young can nurse from their mother’s breast for up to two years, but lactation lasts for nine to thirteen months.

Males reach sexual maturity at around 10 years old, while females reach sexual maturity at 8–11 years old. However, males typically wait until 25–27 years old to begin the mating process because they do not yet have a high enough social status at that age. Males migrate to higher latitudes once they reach adulthood because the water is colder and hunting is more successful there.