Sperm Whale

## Description

The Sperm whale or cachalot (Physeter macrocephalus) is the largest of the toothed whales and the largest toothed predator. It is the only living member of the genus Physeter and one of three extant species in the sperm whale family, along with the Pygmy sperm whale and Dwarf sperm whale of the genus Kogia. The Sperm whale uses echolocation and vocalization as loud as 230 decibels (re 1 µPa m) underwater. It also has the largest brain on Earth, more than five times heavier than a human's. Spermaceti (sperm oil), from which the whale derives its name, was a prime target of the whaling industry and was sought after for use in oil lamps, lubricants, and candles. Ambergris, a solid waxy waste product sometimes present in its digestive system, is still highly valued as a fixative in perfumes, among other uses.

## Appearance

The Sperm whale's unique body is unlikely to be confused with any other species. The whale’s distinctive shape comes from its very large, block-shaped head, which can be one-quarter to one-third of the animal's length. The S-shaped blowhole is located very close to the front of the head and shifted to the whale's left. This gives rise to a distinctive bushy, forward-angled spray. The Sperm whale's flukes (tail lobes) are triangular and very thick. Proportionally, they are larger than that of any other cetacean and are very flexible. The whale lifts its flukes high out of the water as it begins a feeding dive. It has a series of ridges on the back's caudal third instead of a dorsal fin. The largest ridge was called the 'hump' by whalers and can be mistaken for a dorsal fin because of its shape and size. In contrast to the smooth skin of most large whales, its back skin is usually wrinkly and has been likened to a prune by whale-watching enthusiasts. Albinos have also been reported.

## Distribution

Sperm whales are among the most cosmopolitan species. They prefer ice-free waters over 1,000 meters (3,300 ft) deep. They are relatively abundant from the poles to the equator and are found in all the oceans. Although Sperm whales are usually found in deep, off-shore waters, they may also be seen closer to shore, in areas where the continental shelf is small and drops quickly to depths of 310 to 920 meters (1,020 to 3,020 ft). Grown males may even enter surprisingly shallow bays to rest (whales will be in a state of rest during these occasions). There are unique, coastal groups reported from various areas around the globe such as near Scotland's coastal waters, and Shiretoko Peninsula, off Kaikoura, in the Davao Gulf.

## Behavior

Sperm whales are very gregarious and they form groups of around 100 individuals, roughly according to age and gender. More common, however, are loose family groups of about 30 animals. Groups often consist of either "nursery schools" of juveniles and adult females, as distinct from groups of bachelor bulls. Older males are typically solitary except in the breeding season. These whales make clicking sounds for echolocation, but also use a range of other sounds such as groans, whistles, chirps, squeaks, pings, yelps, and wheezes. They also make a stereotyped, repetitive series of around 3-40 clicks when they meet another whale, known as a whale's "coda." A Sperm whale is a very deep diver and may remain underwater from 20 minutes to more than an hour. On surfacing, they usually blow 20 to 70 times before diving again. Sperm whales usually dive between 300 to 800 meters (980 to 2,620 ft), and sometimes 1 to 2 kilometers (3,300 to 6,600 ft), in search of food.[157] Such dives can last more than an hour. They hunt through echolocation. Their clicks are among the most powerful sounds in the animal kingdom and it has been hypothesized that they can stun prey with their clicks.

## Diet

Sperm whales are carnivores (molluscivores) and feed primarily on squid (particularly giant squid), octopi, and deepwater fish, and also sharks and skates.

## Reproduction

Sperm whales have a polygynous mating system, which means that one male mates with multiple females. During the breeding season, they form breeding schools consisting of 1-5 big males and a group of males and females of various ages. There is fierce competition among males for females (which includes battles that leave scars all over the males' heads). Spring is the peak of the breeding season. Gestation lasts for 14-16 months and one calf is born and is nursed for as long as 2 years. Groups of female whales protect their calves by means of a defensive ‘marguerite formation’, where the young are placed in the middle of the group with a circle of females around them, facing their tail outwards. The cycle of reproduction occurs every 2 to 5 years in females, who mature sexually by 8-11 years of age, while males are reproductively mature at about 10 years, although they reach 25 to 27 years of age before they mate.

## Population

### Population threats

Sperm whales suffer from commercial harpoon fisheries in Indonesia, the Lesser Antilles, and Japan. Selective hunting of the biggest breeding males will probably have decreased rates of reproduction, and the loss of the largest female whales from nursery groups will have decreased the groups' survival. Further threats include becoming tangled in fishing gear, collisions with boats, underwater and anthropogenic noise, and an increasing concern as regards the habitat of whales, particularly for deep-diving sperm whales that make use of sound when feeding, communicating, and navigating in the ocean.

### Population number

According to the IUCN Red List, the total Sperm whale population size is unknown but is thought to be between 100,000-360,000 individuals. This species is classified as Vulnerable (VU) on the list of threatened species.

### Ecological niche

It has been stated that Sperm whales help fertilize the surface of the ocean by consuming nutrients in the depths and transporting those nutrients to the oceans' surface when they defecate; this effect is known as the whale pump. This fertilizes phytoplankton and other plants on the surface of the ocean and contributes to ocean productivity and the drawdown of atmospheric carbon.

## Fun Facts

Sperm whale has the largest brain of any animal on Earth.

Many people think the Sperm whale is a very lazy creature because it is often seen carrying out a behavior called logging. The whale is in a position just below the surface, the tail is completely submerged, and it just floats and is very calm.

“Moby Dick”, the movie, is based on a couple of real-life Sperm whales - one being a whale that rammed into and sank a ship called the Essex, and the other an albino male named Mocha Dick.

Sperm whales can dive for up to 2 hours as deep as 3,000 meters, and it is, therefore, the deepest diving mammal.