SPERM WHALE  Physeter macrocephalus

Status

ESA Endangered - throughout its range
MMPA Depleted - throughout its range
CITES Appendix II - throughout its range

 

Taxonomy

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Cetacea

Family: Physeteridae

Genus:Physeter

Species: macrocephalus

 

 

Species Description

Weight: females: up to 15 tons (13,607 kg)

             males: up to 45 tons (40,823 kg)

Length: females: about 36 feet (11 m)

             males: about 52 feet (16 m)

Appearance: mostly dark gray, though some whales have white patches on the belly, with an extremely large head that takes up about 1/3

                     of its total body length

Lifespan: unknown, but females mature around 30 years old and males mature about 50 years old

Diet: large squid, sharks, skates, and fishes

Behavior: they dive to feed and the average dive lasts about 35 minutes to depths of 1,300 feet (400 m), however dives may last over  

                an hour and reach depths over 3,280 feet (1,000 m)

 

Sperm whales (Physeter macrocephalus) are the largest of the odontocetes (toothed whales) and the most sexually dimorphic cetaceans, with males considerably larger than females. Adult females may grow to lengths of 36 feet (11 m) and weigh 15 tons (13,607 kg). Adult males, however, reach about 52 feet (16 m) and may weigh as much as 45 tons (40,823 kg).

 

The sperm whale is distinguished by its extremely large head, which takes up to 25 to 35% of its total body length. It is the only living cetacean that has a single blowhole asymmetrically situated on the left side of the head near the tip. Sperm whales have the largest brain of any animal (on average 17 pounds (7.8 kg) in mature males), however, compared to their large body size, the brain is not exceptional in size.

 

There are between 20-26 large conical teeth in each side of the lower jaw. The teeth in the upper jaw rarely erupt and are often considered to be vestigial. It appears that teeth may not be necessary for feeding, since they do not break through the gums until puberty, if at all, and healthy sperm whales have been caught that have no teeth.

 

Sperm whales are mostly dark gray, but oftentimes the interior of the mouth is bright white, and some whales have white patches on the belly. Their flippers are paddle-shaped and small compared to the size of the body, and their flukes are very triangular in shape. They have small dorsal fins that are low, thick, and usually rounded.

 

Because sperm whales spend most of their time in deep waters, their diet consists of many larger organisms that also occupy deep waters of the ocean. Their principle prey are large squid weighing between 3.5 ounces and 22 pounds (0.1 kg and 10 kg), but they will also eat large demersal and mesopelagic sharks, skates, and fishes. The average dive lasts about 35 minutes and is usually down 1,312 feet (400 m), however dives may last over an hour and reach depths over 3,280 feet (1,000 m).

 

Female sperm whales reach sexual maturity around 9 years of age when they are roughly 29 feet (9 m) long. At this point, growth slows and they produce a calf approximately once every five years. After a 14-16 month gestation period, a single calf about 13 feet (4 m) long is born. Although calves will eat solid food before one year of age, they continue to suckle for several years. Females are physically mature around 30 years and 35 feet (10.6 m) long, at which time they stop growing. For about the first 10 years of life, males are only slightly larger than females, but males continue to exhibit substantial growth until they are well into their 30s. Males reach physical maturity around 50 years and when they are 52 feet (16 m) long. Unlike females, puberty in males is prolonged, and may last between ages 10 to 20 years old. Even though males are sexually mature at this time, they often do not actively participate in breeding until their late twenties.

 

Most females will form lasting bonds with other females of their family, and on average

12 females and their young will form a family unit. While females generally stay with the

same unit all their lives in and around tropical waters, young males will leave when they

are between 4 and 21 years old and can be found in "bachelor schools", comprising of

other males that are about the same age and size. As males get older and larger, they

begin to migrate to higher latitudes (toward the poles) and slowly bachelor schools be-

come smaller, until the largest males end up alone.

 

 

 

 

REFERENCES:

NOAA National Oceanic and Atmospheric Administration, 2012 [online]

http://www.fisheries.noaa.gov/pr/species/mammals/whales/sperm-whale.html

(Accessed 18 march 2016)

 

Sperm Whale Range

Click for larger view

Credit: NOAA

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