Dolphin

Along with tigers and elephants, dolphins are often listed when someone asks, “What is your favorite animal?”

Many people have become familiar with the playful antics of dolphins through films like Flipper and Dolphin Tale. But there is much more to these animals and their behavior! Keep reading to learn more facts about these amazing animals.

5 Amazing Dolphin Facts!

• These animals are social and typically live in groups called pods. Most pods have up to 30 individuals, but superpods of more than 1,000 dolphins have been observed!
• Not all of them live in ocean habitats. There are a few remaining species of river dolphins – one of them is pink in color!
• They have been known to help or protect humans, often by scaring away sharks.
• Beginning in the 1960s, these animals were trained for military purposes such as locating and collecting lost objects, delivering items to divers, guarding vessels, or holding a surveillance camera in their mouths. The program ended in the 1990s, and some of the retired animals began working with children as therapy animals.
• These animals show self-awareness in that they are able to recognize themselves and experience individuality. Only a few animals – apes, elephants, dolphins, and toothed whales – demonstrate this trait.

Where to Find Dolphins

These animals can be found in all of the world’s oceans, and they are especially prominent in coastal areas. Five species live in brackish habitats or freshwater river systems in South America or Asia.

Scientific Names

The common name “dolphin” comes from the Greek delphis, meaning “womb.” Even these ancient observers realized dolphins’ classification as mammals, or animals with a womb. Oceanic species, along with their scientific names, are as follows:

• Australian snubfin -, Orcaella heinsohni
• Irrawaddy -, Orcaella brevirostris
• La Plata -, Pontoporia blainvillei
• Long-beaked common -, Delphinus capensis
• Short-beaked common -, Delphinus delphis
• Common bottlenose –, Tursiops truncatus
• Indo-Pacific bottlenose -, Tursiops aduncus
• Burrunan -, Tursiops australis
• Northern right whale -, Lissodelphis borealis
• Southern right whale dolsphin, Lissodelphis peronii
• Costero, Sotalia guianensis
• Indo-Pacific humpback -, Sousa chinensis
• Atlantic humpback -, Sousa teuszii
• Atlantic spotted -, Stenella frontalis
• Clymene -, Stenella clymene
• Pacific white-sided -, Lagenorhynchus obliquidens
• Pantropical spotted -, Stenella attenuata
• Peale’s -, Lagenorhynchus australis
• Spinner -, Stenella longirostris
• Striped -, Stenella coeruleoalba
• Rough-toothed -, Steno bredanensis
• Chilean -, Cephalorhynchus eutropia
• Commerson’s -, Cephalorhynchus commersonii
• Haviside’s -, Cephalorhynchus heavisidii
• Hector’s -, Cephalorhynchus hectori
• Risso’s -, Grampus griseus
• Fraser’s dol-phin, Lagenodelphis hosei
• Atlantic white-sided -, Lagenorhynchus acutus
• Dusky –, Lagenorhynchus obscurus
• Pacific white-sided -, Lagenorhynchus obliquidens
• Hourglass -, Lagenorhynchus cruciger
• White-beaked dolphin, Lagenorhynchus albirostris

There are also a number of small “whales” that are genetically in the same classification as dolphins:

• Killer whale or orca, Orcinus orca
• Pygmy killer whale, Feresa attenuata
• False killer whale, Pseudorca crassidens
• Long-finned pilot whale, Globicephala melas
• Melon-headed whale, Peponocephala electra

River dolphin common and scientific names are as follows:

• Baiji, Lipotes vexillifer
• South Asian river dolphin, Platanista gangetica
• Amazon river dolphin, Inia geoffrensis
• Araguaian river dolphin, Inia araguaiaensis
• Bolivian river dolphin,Inia boliviensis
• Tucuxi, Sotalia fluviatilis

Evolution

Dolphins’ earliest ancestors were terrestrial ungulates. Sixty million years ago, one of their ancestors which was also the ancestor of the hippo diverged from the main evolutionary branch at the time. Their distant forbears however, first began to associate with the sea approximately 49 million years ago and about 1 million years later, another separation occurred from a bovid-like ungulate, known as the  Indohyus. The full separation between dolphins and hippos occurred 40 million years ago as a result of their common evolutionary pathway branching into cetacea and anthracotheres.

Between 34 – 39 million years ago, their transformation from aquatic to terrestrial mammals was complete.

The lineage of the anthracotheres would become extinct, 37 million years later, leaving only one line which would provide the modern hippos.

Size, Appearance, & Behavior

Maui’s dolphin is the smallest, with a length of 1.7 meters (5 ft 7 inches) and a weight of 50 kg (110 lbs). The largest is the killer whale, weighing in at 10 tons and reaching 9.5 meters (31 ft) in length.

Most people visualize them as grey in color, but many have blocks of black, white, or even yellow. Some are speckled. One species of river dolphin is even pale pink.

These are communicative social animals that live in groups called pods.

Migration

Some species migrate when the water temperature changes or in order to follow food sources.

Diet

These animals are carnivores.

What Do Dolphins Eat?

These animals mainly eat fish, squid, and ocean invertebrates. They may also opportunistically feed on small birds or mammals. For a more complete list of foods dolphins eat, check out our “What Do Dolphins Eat?” page.

Predators and Threats

Adults have few predators. Their primary threat is humans. Many die each year after becoming entangled in fishing nets.

What Eats Dolphins?

Sharks and orcas may opportunistically prey on juveniles.

Reproduction, Babies, and Lifespan

These animals typically give birth to just one offspring, but twins and triplets have been observed. The infant feeds on milk, and the mothers train and care for their babies for several years. Dolphins typically live 10-20 years in the wild.

Intelligence

Dolphins have brains that are larger than human brains and are among the most intelligent species on Earth. They possess surprisingly complex communication. Yet, they’re not as smart as humans. What are the key differences between human brains and dolphin brains? One difference is that dolphin brains have a relatively small prefrontal cortex and a smaller hippocampus. These smaller areas on the brain lead to dolphins having less higher-level thinking and memory when compared to humans. Yet, dolphins are still perhaps the second most intelligent species on Earth.

Population

The most common species number into the hundreds of thousands or even millions. The most endangered species, the Irrawaddy dolphin, has only 92 known individuals.

Read about the world’s dolphin population.

1. David Burnie, Dorling Kindersley (2011) Animal, The Definitive Visual Guide To The World's Wildlife
2. Tom Jackson, Lorenz Books (2007) The World Encyclopedia Of Animals
3. David Burnie, Kingfisher (2011) The Kingfisher Animal Encyclopedia
4. Richard Mackay, University of California Press (2009) The Atlas Of Endangered Species
5. David Burnie, Dorling Kindersley (2008) Illustrated Encyclopedia Of Animals
6. Dorling Kindersley (2006) Dorling Kindersley Encyclopedia Of Animals
7. David W. Macdonald, Oxford University Press (2010) The Encyclopedia Of Mammals