Sperm Whale(Physeter macrocephalus)
By: Bailey Bennett and Luke Fagan
A large, blackish-brown whale with huge head and truncate snout; lower jaw small, long, and slender, the symphysis extending half the length of rami; the single blowhole on anterior left edge of snout; no dorsal fin, but conspicuous hump; eye very small, low, and near angle of mouth; pectoral fin short and relatively broad; upper jaw lacking functional teeth; lower jaw with 22-24 large, sharp teeth on each side. Total length of males, up to 20 m; females much smaller. Weight of a male 13 m long, 39 metric tons.... so in other words The girth of this hot whale is 32,000 pounds. The lifespan of this sexy whale is 70 years. The length of this gorgeous whale is 40 feet. This beauty has rough and wrinkly skin.
Historically, the primary threat to sperm whales was commercial hunting that occurred between the early 17th century and 1986 when the ban on commercial whaling began. The sperm whale was hunted for its spermaceti oil which was used to make candles and lubricate machinery. Early whalers hunted with basic equipment and travelled extensively to catch their prey. The intensity with which whales were hunted increased with the development of more sophisticated equipment that included specially designed ships that made it easier to haul whales onboard. Large males in particular were targeted and this naturally caused a decrease in the average size of males as well as a additional drop in pregnancy rate. In addition to the reduction in number of males, the loss of older females from the social group also meant the loss of knowledge and care for young from the group and the impacts of this loss on the group are yet to be understood.
Breeding behavior in sperm whales is similar to harem formation — a single, dominant male accompanies a group of females and defends the group against competing males. During this time, smaller males are driven off to form their own "bachelor groups" and battles between rival males for control of the harem may occur. Twenty to thirty females may comprise a harem but many of them may already be pregnant or tending young. The gestation period is approximately 15 months, the period of lactation is 1-2 years, and there is a "resting period" of up to 10 months following weaning before the females will mate again. The breeding cycle therefore, may take as long as 5-7 years.
All whales in a pod use the same small selection of patterned clicks. Scientists think the animals use the sounds to show other whales in the pod that they're part of the same gang. However, researchers found that the set of patterned clicks this mother used was subtley different to the other clicks they recorded. 'The coda she used dropped one click off the end. It's not that easy to tell the difference, but it's probably clear to these animals. It was a surprise to find this difference.'