Sperm whale family Totally Explained

Everything about Kogiidae totally explained

The sperm whale family or simply the sperm whales is the collective name given to three species of whale found worldwide; the Sperm Whale, the Pygmy Sperm Whale and the Dwarf Sperm Whale. The name Sperm Whale comes from sailors of whaling boats who thought that the spermaceti on the whales head was actual sperm from the reproductive system. There are three different taxonomic interpretations of this 'family'. The last of these listed here's the one that has generally been used since 1998.

All three species are members of the Kogiidae family.
All three species are members of the Physeteridae with Kogiinae as a subfamily.
Two distinct families - Physeteridae and Kogiidae - in the superfamily Physeteroidea which also includes basal prehistoric species.

In any case there's complete agreement that there are two living genera - Physeter containing one species - the Sperm Whale - and Kogia containing the Dwarf Sperm Whale and Pygmy Sperm Whale.

Characteristics

The Sperm Whale is the largest species of toothed whale, with adult males growing to be about 15-18 metres (50-60 feet) long, and weighing about 45-70 tonnes. The two kogiid species are much smaller, at only around 2.5 to 3.5 metres (9-11 feet) in length, and weighing 350-500 kilograms (770-1,100 pounds).
The body of sperm whales is robustly proportioned, with paddled-shaped flippers. The lower jaw is always relatively small in relation to the upper jaw. The nasal bones of sperm whales are distinctly asymmetrical, with the blowhole being located on the left side of the head; in the Sperm Whale this is near the top of the head, while on the kogiids it's further forward. All species have a large number of similar, and relatively simple, teeth. In the kogiids, and sometimes also in the Sperm Whale, the teeth in the upper jaw don't erupt, and are sometimes altogether absent.
The eyes of sperm whales are unable to swivel in their sockets, and possess only a vestigial anterior chamber. It is likely that echolocation is a far more important sense to these animals than vision. Another common characteristic is the spermaceti, a semi-liquid waxy white substance filling the 'case' or spermaceti organ in the whale's head, which has a role in diving and maintaining buoyancy. (See the individual species articles for further details). All three species dive to great depths to find food, although the Sperm Whale is believed to dive much deeper than either of the kogiids. Members of both families eat squid, fish, and even sharks. Gestation lasts from nine to fifteen months, depending on species. The single calf remains with the mother for at least two years, before being weaned. Sperm whales don't reach full sexual maturity for several years. All species congregate together in 'pods' or herds, although these are typically smaller in the kogiids.

Evolution

Some scientists say that the sperm whale family is a living fossil group because they're a very ancient lineage of cetaceans. The group's fossil range extends back to the Oligocene - about 35-30 million years ago, with an ancestry tracing back from the latest Eocene before diverging from the remainder of the Odontocetid line, leading to the dolphins, and porpoises.
The fossil record suggests that sperm whales were more common in the Miocene, where basal lineages (such as Zygophyseter and Naganocetus) existed. The kogiids appear to have diverged from the physterid sperm whales in the Pliocene, around 7 million years ago.

Classification

ORDER: CETACEA

Suborder: Mysticeti
Suborder: Odontoceti
- Superfamily: Platanistoidea
- Family: Delphinidae
- Family: Phocoenidae
- Family: Monodontidae
- Family: Physteridae
  - Sperm Whale Physeter macrocephalus
- Family: Kogiidae
  - Pygmy Sperm Whale Kogia breviceps
  - Dwarf Sperm Whale Kogia simus
- Family: Ziphiidae

Further Information

Get more info on 'Kogiidae'.

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