FaunaHub

Dolphin

Marine MammalCetaceanSocial

Common bottlenose dolphin (Tursiops truncatus) surfacing in clear water.

Common bottlenose dolphin (Tursiops truncatus).

Image: NASA, Public domain, via Wikimedia Commons (NASA).

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.

Appearance & Recognition

Dolphins share a clearly mammalian, streamlined body plan: a torpedo-shaped torso, a single dorsal fin, two pectoral flippers, and a horizontal tail fluke used for propulsion. The snout is typically extended into a beak (the "rostrum") of variable length depending on species — long and slender in spinner and common dolphins, shorter and blunter in bottlenose dolphins, and almost absent in some species such as the orca and Risso's dolphin.

Colouration is typically counter-shaded — darker above, lighter below — which provides camouflage against both sunlit surface waters and deeper water. Many species carry distinctive cape patterns, eye markings, or flank stripes. Field identification at sea usually combines dorsal-fin shape and position, overall body proportions, behavioural cues (e.g. bow-riding, surface acrobatics), and group size rather than any single feature.

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 — see the shark profile for the practical distinguishing features.

More photos of the dolphin

Common bottlenose dolphin (Tursiops truncatus) bow-riding a ferry between Pico and Faial, Azores.

Bottlenose dolphin (Tursiops truncatus) bow-riding a ferry, Azores.

Image: Jules Verne Times Two, CC BY-SA 4.0, via Wikimedia Commons.

Two common bottlenose dolphins (Tursiops truncatus) swimming together near the Azores ferry.

A pair of bottlenose dolphins moving in close formation alongside a vessel.

Image: Jules Verne Times Two, CC BY-SA 4.0, via Wikimedia Commons.

Frequently Asked Questions — Dolphin

Are dolphins fish or mammals?
Dolphins are mammals. They are warm-blooded, breathe air through lungs (via a blowhole), give birth to live young, and nurse their offspring with milk. They evolved from land-dwelling ancestors over tens of millions of years.
How intelligent are dolphins?
Dolphins, particularly bottlenose dolphins, show behaviours associated with high cognition in research settings — including mirror self-recognition reported in some individuals, problem-solving, tool use in certain populations, and complex social learning. Discussion of intelligence in non-human animals is best framed in terms of specific documented behaviours rather than ranking.
How does echolocation work?
Dolphins produce high-frequency clicks from structures in their forehead. The returning echoes are received primarily through fatty tissues in the lower jaw and conducted to the inner ear. By interpreting these echoes, dolphins can detect, locate, and characterise objects — including prey hidden in sediment.
Are dolphins dangerous?
Wild dolphins are generally not dangerous to humans, but they are large, powerful, wild animals. Interactions with habituated individuals, captive animals, or stressed animals can cause injury. Most marine authorities discourage approaching, feeding, or swimming directly with wild dolphins.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.