Dolphin
Marine MammalCetaceanSocial
Overview
"Dolphin" is a common name applied to a number of small to medium-sized toothed whales (suborder Odontoceti). The majority of species belong to the family Delphinidae, the oceanic dolphins, which includes the well-known common bottlenose dolphin (Tursiops truncatus) used as the reference species on this page. Several distinct families of freshwater "river dolphins" are also recognised.
Dolphins are marine mammals — warm-blooded, air-breathing, viviparous and milk-producing — and they are notable for sophisticated echolocation, complex social behaviour, and high reported cognitive performance in research settings.
Habitat & Range
Dolphins occupy a wide variety of marine habitats including coastal waters, open pelagic ocean, estuaries, and some tropical river systems (in the case of river dolphins). The common bottlenose dolphin is widely distributed in temperate and tropical waters of the world's oceans, often using coastal and near-shore habitats.
Diet
Dolphins are predominantly piscivorous, with diets centred on fish and squid. Prey selection varies by species and region. Foraging behaviours can be highly developed and include cooperative herding of fish schools, "mud-ring" feeding in some bottlenose populations, and the use of echolocation to detect and locate buried or hidden prey.
Behavior
Most dolphin species are highly social, living in groups known as pods. Pod composition varies — from small stable family-related units to large temporary aggregations of hundreds of individuals. Communication uses a wide repertoire of whistles, clicks and burst-pulsed sounds; individually distinctive "signature whistles" have been documented in bottlenose dolphins.
Echolocation — the production of high-frequency clicks and the interpretation of returning echoes — is central to navigation and prey detection in low-visibility water.
Human Interaction & Conservation
Conservation pressures vary by species and region but commonly include bycatch in fishing gear, habitat degradation, chemical and noise pollution, prey depletion, and direct hunts in some areas. Several river dolphin populations are particularly threatened. Status should be checked species-by-species on the IUCN Red List.
Similar Animals
Other cetaceans include whales (large baleen and toothed whales) and porpoises (a separate family of small cetaceans). Sharks are sometimes confused with dolphins by casual observers but are cartilaginous fish, not mammals.