Sperm whale

  (Physeter macrocephalus)
Sperm whale

Description: : This whale has a very distinctive, huge squarish head occupying at least one-third of its body and projecting, often up to 1.5 m, well beyond its lower jaw. The large head contains a cavity called the spermaceti organ which is a mass of web-like tubes filled with a yellow wax. This organ is believed to be used in maintaining buoyancy and may also be used to focus sonar clicks.It has a huge brain that weights about 9 kg. It is the largest brain of any animal. The Sperm Whale has a single blowhole that is s-shaped and is located on the left side of the front of its head which gives a bushy blow projected forwards at a sharp angle to the left. The Sperm Whale has no dorsal fin but it has a distinct triangular or rounded hump two-thirds along the body followed by a spinal ridge to broad triangular and deeply notched tail flukes. The flippers are approx. 1.5 m. The Sperm Whale has a robust body with corrugations in the skin giving it a shrivelled prune-like appearance.

The skin is dark grey or brownish grey. It is paler at the front of the head and on the belly, with white fringes to the mouth, particularly in the corners.

Size: Sperm Whales are the largest toothed whales. Adult males grow to be about 18 m long, weighing about 40-50 tons. Females are smaller, about 11-13 m long, weighing about 14-18 tons.

Behaviour: Sperm Whales are the deepest diving whales. Although they live at the surface, they dive to hunt giant squid that are bottom dwellers. They have been known to dive as deeply as 1500 m. and they can hold their breath for about an hour. Although most of time, they dive to 600-700 m, taking between 35 and 45 minutes.

The bonds between the species of Sperm Whale are strong and long-lasting. The members of a pod protect the young, the sick and the injured. Groups of females with their young are common. This group structure allows a mother to dive very deeply to hunt while leaving her young calf at the surface and is protected by the pod.

Dive sequence: The sperm whales breathing sequence involves from 10-15 minutes on the surface with 50-60 breaths during that time. As it lifts its head for a final breath, only two thirds of its body is visible. Its tail is hanging down and a part of the head, the dorsal fin or parts of the back are exposed at the surface. The blow is a noisy, single stream that rises up to 15 m above the surface of the water and points forward and to the left of the whale at a 45° angle. The longer and deeper is the dive, the higher the spout. Sperm Whales are often seen logging and are relatively easy to approach in this state. The Sperm Whale then straightens and stretches its body, gently arches its back and briefly disappears. It accelerates and reappears a little farther on. Arching its back until it is high out of the water, making the rounded hump and knuckles. along the upper side clearly visible, it then throws its flukes and the rear third of its body high into the air and drops vertically, with barely a ripple.

They can swim very slowly and they sail 10 knots on average, although they can reach 20 knots if they feel threatened.

Vocalization: Sperm Whales use echolocation to catch their prey in the dark oceanic depths. Mothers also use it to keep track of their young calf when they are diving to hunt; a calf cannot dive very deep. It has to breathe much more frequently than the mother does.

Distribution: : The Sperm Whale is cosmopolitan in deep waters of all seas except close to ice edges. It is most common in submarine trenches at the edge of the continental shelf but may occur inshore where water is deeper than 200m. Migration to favoured areas for feeding and breeding may be undertaken however females undergo less extensive seasonal migration than males. Winter is spent in temperate and tropical waters.

Feeding: Sperm whales are carnivores that mostly eat giant squid that live on the ocean bottom at great depths. They also eat fish, octopus, and some species of sharks, for that they may use echolocation system.

Reproduction: The breeding of Sperm Whales are not dependent on the seasons. The gestation period is over 15 months and the calf is born tail first near the surface of the water. The newborn instinctively swims to the surface within 10 seconds for its first breath; it helped by its mother. Within 30 minutes of its birth the baby whale can swim. The newborn calf is about 3.5-4.5 m long and weights about 1 ton. There is almost always one calf. The interval between births is about 3-4 years. A female reaches maturity at 7-12 years (males reach maturity at 18-19 years) and lives to be about 40 years old. On average, a female will give birth to about 7-10 calves. Frequently, other whales "assist" in the birth. The baby is nurtured with its mother's milk and is weaned in about 2 years. Calves drink 20 kg of milk each day.