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Porpoises (/ ˈ p ɔː r p ə s ɪ z /) are small dolphin-like cetaceans classified under the family Phocoenidae. Although similar in appearance to dolphins, they are more closely related to narwhals and belugas than to the true dolphins. [1] There are eight extant species of porpoise, all among the smallest of the toothed whales.
A common bottlenose dolphin (Tursiops truncatus). A dolphin is an aquatic mammal in the clade Odontoceti (toothed whale).Dolphins belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the brackish dolphins), and possibly extinct Lipotidae (baiji or Chinese river dolphin).
Wood pilings grouped into a pair of dolphins serving as a protected entryway to a boat basin. A dolphin is a group of pilings arrayed together to serve variously as a protective hardpoint along a dock, in a waterway, or along a shore; as a means or point of stabilization of a dock, bridge, or similar structure; as a mooring point; and as a base for navigational aids.
Excluding dolphins and porpoises, odontocetes consist of four families: belugas and narwhals (monodontids), sperm whales (physeterids), dwarf and pygmy sperm whales (kogiids), and beaked whales (ziphiids). [6] The differences between families of odontocetes include size, feeding adaptations and distribution.
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 differences between the two groups are that porpoises have a less pronounced beak, and have spade-shaped teeth as opposed to conical.
The dolphin, often elaborated fantastically, might be constructed as a spout for a fountain. [34] On a modern-era fountain in the Palazzo Vecchio, Florence, Italy, Cupid seems to be strangling a dolphin. [35] Dolphins were often portrayed in antiquity as friendly to humans, and the dolphin itself could represent affection.
Flippers are one of the principal control surfaces of cetaceans (whales, dolphins and porpoises) due to their position in front of the center of mass, and their mobility which provides three degrees of freedom. [4] The tubercles on the flippers of humpback whales improve the hydrodynamics of the flipper at their size. Breaking up channels of ...
The dolphins drive a school of fish towards the shore where humans await with their nets. In the confusion of casting nets, the dolphins catch a large number of fish as well. Intraspecific cooperative foraging techniques have also been observed, and some propose that these behaviours are transmitted through cultural means.