Taxonomy/Description

Sperm whales belong to the Mammalian Order Cetacea, in the suborder Odontoceti.  All toothed whales belong to the suborder Odontoceti, which is Latin for "toothed whales".  The sperm whale belongs to the sperm whale family, Physeteridae.  The other members of this family are the pygmy sperm whale and the dwarf sperm whale.  The sperm whale's scientific name is Physeter macrocephalus.  The generic name, Physeter, means "blow pipe".  The specific name, macrocephalus, means "large head".  Recent analysis of sperm whale DNA has lead some researchers to believe that sperm whales are more closely related to baleen whales, of the suborder Mysticeti, than to toothed whales, of the suborder Odontoceti.  The anatomy of the sperm whale is very recognizable.  A single blowhole is located on the left side of the head.  Due to the position of the blowhole, the spout is unmistakable.  The spout is characterized by a forward burst of mist at a 45 degree angle.  Another interesting anatomical quality of sperm whales are their taste receptors.  They have taste receptors throughout their mouth, which probably aid in detecting changes in water salinity.  Largest of the toothed whales, male sperm whales grow to lengths of 68ft or more, and weigh up to 70 tons.  Females are smaller, reaching about 39ft in length and weighing up to 20 tons.

Habitat/Diet

The sperm whale is found in all oceans.  Females and juveniles remain in more temperate waters surrounding the equator, while males journey to the polar regions.  Two separate breeding stocks are believed to exist, a northern hemisphere stock and a southern hemisphere stock.  Sperm whales dive deep for their prey.  Feeding primarily on squid and other deep ocean creatures, sperm whales dive to depths of 1,200m.  Echolocation is used to locate prey in these deep waters with very little light.  Some species of potential prey are octopus, fish, shrimp, and crabs.  Non-food objects found in sperm whale stomachs include stones and tin cans.  The presence of such items imply that sperm whales dive into the seabed to obtain prey. 

The sperm whale is well adapted for deep-diving.  Sperm whale muscle absorbs up to 50 percent of the total oxygen store.  This muscle absorption is double the efficiency of terrestrial mammals, and significantly greater than even baleen whales and seals.  Another adaptation for deep diving lies with the function of the large spermaceti organ.  Unique to sperm whales, the spermaceti organ is believed to play a very important role in deep diving.  It is hypothesized that the density of the spermaceti organ changes as the whale's depth changes.  As the whale dives, the spermaceti wax cools from the flow of water over the whale's nasal passages and sinuses.  The density of the wax increases, adding weight to the head which assists descent.  When resurfacing, the blood flow in the capillaries of the head increases, warming the wax.  The sperm whale's head becomes more buoyant, which assists in the ascent.  Such an adaptation allows the whale to rise to the surface for air with little effort, which is especially useful after an exhaustive dive and hunt in the deep ocean.

Behavior/Reproduction

Sperm whales are social mammals.  They form pods of up to 100 individuals.  The average pod size for coastal whales is 20 whales, and 3-7 for open ocean whales.  During breeding season, males join with nursery school pods of juveniles and adult females.  These harem schools are facilitated by the single bull whale.  Fighting with other males for the control of the harem is not uncommon.  The adult males use head-butting and biting to fend off competitors.  Peak breeding season occurs in December for the southern stock, and six months later for the northern stock.  Calves are born 14-15 months later.  They remain in the nursery school for two years, continuing to suckle.  Suckling may even occur for several years after weaning.  Females reach sexual maturity at 7-12 years.  Puberty is extended in males, beginning at about 9-11 years, with full sexual maturity at 18-19 years.  A growth spurt occurs at the end of puberty.  However, males do not reach social maturity until about 26 years.

Sperm whales are very protective.  In fact, such a quality was very dangerous during the time sperm whales were hunted.  Once a whale is injured, the other members of the pod will circle the dying animal.  The group of whales provide support for the whale, stabilizing its position with their heads.  This formation is called the "marguerite flower".  It was a very dangerous position because it allowed whalers to systematically harpoon each whale.

Conservation

Sperm whales were the primary targets of New England whalers during the 18th and 19th centuries.  The whales were mainly hunted for sperm oil.  The oil was taken from blubber, and whale flesh was sold for human consumption.  Two other products, unique to sperm whales are also valued.  Spermaceti oil is used as an industrial lubricant.  It is very effective, and is even used in space research.  "Ambergis" is the other popular sperm whale derivative.  This substance is used as a fixative in perfumes and cosmetics.  Taken from the intestine, ambergis is believed to be a form of excrement.

The International Whaling Commission decided to end sperm whaling in 1985.  The original stocks of the southern hemisphere numbered 170,000 males, and 160,000 females.  They have since been reduced to about 71,000 males 125,000 females.  Extinction seems highly unlikely for the sperm whale, given its protection and population size.