sperm whale family

Sperm whales Fossil range: Early or Middle Oligocene to Recent
Two Sperm Whales, Physeter macrocephalus
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Cetacea Suborder: Odontoceti
Families and genera
Kogiidae Gill, 1871   Kogia Physeteridae Gray, 1821   Physeter

The sperm whale family or simply the sperm whales is the collective name given to three species of whale, the Sperm Whale, the Pygmy Sperm Whale and the Dwarf Sperm Whale. There are three different taxonomic interpretations of this 'family'. The last of these listed here is the one that has generally been used since 1998.

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

In any case there is 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.

Sperm whales are the largest toothed whales. Adult males grow to be about 50-60 feet (15-18 m) long, weighing about 40-50 tons (36-45 tonnes). Females are smaller, about 33-40 feet (10-12 m) long, weighing about 14-18 tons. The four-chambered heart of the average sperm whale weighs about 277 pounds (126 kg) - about as much as two average adult human beings.

The common characteristic of each species is the spermaceti, a semi-liquid waxy white substance filling the case or spermaceti organ in the whale's head. See the individual species articles for further details.

Sperm whales are known to dive incredible depths to find food. Sperm whales eat squid, fish and even sharks. They belong to the group of toothed whales, odontoceti, which have teeth instead of baleen. The sperm whale has the largest brain of any animal on earth though this does not imply they are particularly intelligent.

Some scientists say that the sperm whale family is a living fossil group because they are a very ancient lineage of cetaceans. The group's fossil range extends back in the Oligocene - about 35-30 million years ago, with an ancestry tracing back from the latest Eocene before diverging from the Odoncetid line, a line that will eventually lead to 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.

References

Donate to Wikimedia