The killer whale or orca (Orcinus orca), or less commonly, blackfish, is the largest species of the dolphin family. It is
found in all the world's oceans, from the frigid Arctic and Antarctic regions to warm, tropical seas. Some killer whale populations
feed mostly on fish while others hunt sharks and marine mammals, including sea lions, seals, walruses and even large whales.
Porpoises are small cetaceans of the family Phocoenidae; they are related to whales and dolphins. They are distinct from dolphins,
although the word "porpoise" has been used to refer to any small dolphin, especially by sailors and fishermen. The most obvious
visible difference between the two groups is that porpoises have flattened, spade-shaped teeth distinct from the conical teeth
of dolphins, and shorter beaks.
The sperm whale, (Physeter macrocephalus), is a species of marine mammal in the order cetacea, a toothed whale (odontocete)
with the largest brain of any animal. The whale was named after the milky-white waxy substance, spermaceti, found in its head
and originally mistaken for sperm. The sperm whale is the only member of the genus Physeter, the synonym Physeter catodon
refers to the same species.
A beaked whale is any of at least twenty species of small whale in the family Ziphiidae. They are one of the least-known families
of large mammals: several species have only been described in the last two decades, and it is entirely possible that more
remain as yet undiscovered. Six genera have been identified. Three of these, Indopacetus, the Hyperoodon and the Mesoplodon,
are united in a single subfamily, the Hyperoodontinae.
Oceanic dolphins are the members of the Delphinidae family of cetaceans. These aquatic mammals are related to whales and porpoises.
They are found worldwide, mostly in the shallower seas of the continental shelves. As the name implies, these dolphins tend
to be found in the open seas, unlike the river dolphins, although a few species such as the Irrawaddy Dolphin are coastal
or riverine.
The sperm whale family, or sperm whales, is a common name for the family Physeteridae or superfamily Physeteroidea. The three
existing species of whale are the Sperm Whale, in the genus Physeter, and the Pygmy Sperm Whale and Dwarf Sperm Whale, in
the genus Kogia.
