Mammal Directory

Mammals

Explore mammals from tiny bats and rodents to primates, carnivores, ungulates, whales, and elephants. Each profile connects core facts with habitat, lifespan, traits, and conservation information.

Scientific names IUCN status Lifespan

Explore more

Browse Mammal Groups

Use these shortcuts to move into more specific animal groups.

Carnivora Primates Rodents Bats Eulipotyphla Ungulates Cetacea Lagomorpha Pangolins Proboscidea Monotremes

Cetacea

Cetacea is an order of mammals, including about 90 existing fish-like, naked-skinned aquatic mammals and their extinct early relatives, collectively known as whales or cetaceans. The larger ones are usually called whales, and the smaller ones are called dolphins. Most of them live in shallow seas, and a few live in fresh water.

I. Introduction to Cetacea

1. Defining Characteristics:

Cetaceans are fully aquatic mammals with streamlined, fusiform bodies.
Forelimbs are modified into flippers; hind limbs are absent externally.
They possess a thick layer of blubber for insulation, and most have a dorsal fin or ridge.
Breathing is through a blowhole (or pair of blowholes in baleen whales) located on top of the head.
Reproduction, birth, and nursing occur entirely in the water.

2. Diversity and Distribution:

About 90 extant species of cetaceans inhabit all the world’s oceans and some rivers.
They range from the enormous blue whale (the largest animal ever known) to small porpoises and dolphins.

II. Evolutionary History

1. Origins:

Cetaceans evolved from terrestrial ancestors during the Eocene epoch (around 50 million years ago). Early fossils like Pakicetus indicate that their ancestors were land-dwelling, wolf-sized mammals. Over millions of years, these ancestors adapted to increasingly aquatic lifestyles.
The discovery of transitional fossils (e.g., Ambulocetus, Rhodocetus) shows the gradual modification from land locomotion to aquatic propulsion using tail flukes and forelimbs as flippers.

2. Transition to Full Aquatic Life:

By the late Eocene, early cetaceans were fully aquatic. Two major lineages diverged: the baleen whales (Mysticeti) and the toothed whales (Odontoceti).
Molecular and morphological data confirm that cetaceans share a close common ancestor with even-toed ungulates (Artiodactyla), especially hippopotamuses. This discovery led to the combined grouping known as Cetartiodactyla.

3. Adaptive Radiations:

Mysticetes adapted filter-feeding apparatuses (baleen plates) to exploit large amounts of small prey (krill, zooplankton).
Odontocetes developed echolocation abilities to navigate and hunt in often murky underwater environments, feeding on fish, squid, and sometimes marine mammals.

III. Classification Overview of Cetacea

Cetacea is traditionally divided into two suborders:

Suborder Mysticeti (Baleen Whales): Characterized by baleen plates instead of teeth, used to filter small prey from the water. They generally have two blowholes.
Suborder Odontoceti (Toothed Whales): Possess teeth (in varying numbers and shapes) and echolocation abilities. They have a single blowhole.

Below are the major families and some representative genera:

Suborder Mysticeti (Baleen Whales)

Family	Representative Genera/Species	Notes
Balaenidae (Right and Bowhead Whales)	Eubalaena (Right whales), Balaena (Bowhead whale)	Large heads, long baleen plates, slow-moving filter feeders.
Balaenopteridae (Rorquals)	Balaenoptera (Blue whale, Fin whale), Megaptera (Humpback whale)	Streamlined, often pleated throats, gulp-feeding strategy.
Eschrichtiidae (Gray Whale)	Eschrichtius (Gray whale)	Bottom-feeder, short baleen, migratory along coastal routes.
Cetotheriidae (Pygmy Right Whale)	Caperea (Pygmy right whale)	Rare and enigmatic family; smallest baleen whale.

Suborder Odontoceti (Toothed Whales)

Family	Representative Genera/Species	Notes
Physeteridae (Sperm Whales)	Physeter (Sperm whale)	Large head with spermaceti organ, deep divers feeding on squid.
Kogiidae (Pygmy Sperm Whales)	Kogia (Pygmy and Dwarf sperm whales)	Small, elusive whales with squid-based diet.
Ziphiidae (Beaked Whales)	Ziphius (Cuvier's beaked whale), Mesoplodon (various species)	Deep-diving, elusive, many species poorly known.
Monodontidae (Narwhal, Beluga)	Monodon (Narwhal), Delphinapterus (Beluga)	Arctic whales with unique features (tusk in narwhal, white beluga).
Phocoenidae (Porpoises)	Phocoena (Harbor porpoise), Neophocaena (Finless porpoise)	Small, robust, lacking a prominent beak, spade-shaped teeth.
Delphinidae (Dolphins)	Tursiops (Bottlenose dolphin), Orcinus (Killer whale), Delphinus (Common dolphin)	Highly diverse, social, and intelligent; largest Odontoceti family.
Iniidae (New World River Dolphins)	Inia (Amazon river dolphin)	Freshwater habitats in South America, long beaks, poor vision.
Pontoporiidae (La Plata Dolphin)	Pontoporia (La Plata dolphin)	Coastal and estuarine waters of eastern South America.
Platanistidae (South Asian River Dolphins)	Platanista (Ganges and Indus river dolphins)	Nearly blind, rely on echolocation in muddy river waters.

(Additional notes: The family Lipotidae, representing the Yangtze River dolphin (Lipotes vexillifer), is functionally extinct. Classification may vary slightly as some taxonomists treat river dolphins differently.)

IV. Summary

Cetaceans represent a remarkable evolutionary journey from land to water. Their extensive adaptive radiation has produced giants like the blue whale as well as highly social and intelligent dolphins and elusive deep-diving beaked whales. Modern molecular studies have situated cetaceans within the order Cetartiodactyla, reaffirming their close kinship with terrestrial ungulates such as hippos. Yet, historically and for the sake of clarity, Cetacea remains a well-recognized grouping for whales, dolphins, and porpoises, illustrating one of the most extraordinary transitions in mammalian evolution.

Species directory

Browse Mammals

Search the animals shown on this page or narrow them by IUCN conservation code.

Striped Dolphin

Stenella coeruleoalba

CetaceaCan live for 50+ years, and some studies suggest maximum ages approaching about 60 years.

The striped dolphin is one of the most widespread and frequently encountered offshore dolphins. It is famous for its crisp body st···

Sperm Whale

Physeter macrocephalus

CetaceaTypically lives 60–70 years, and some individuals may survive longer based on long‑term identification studies.

The sperm whale is the largest living toothed whale and one of the ocean’s most formidable deep‑sea predators. It is instantly r···

Southern Right Whale

Eubalaena australis

CetaceaOften lives 70+ years; long‑term photo‑ID studies suggest some individuals may survive for a century or more.

The southern right whale is one of the Southern Hemisphere’s most iconic baleen whales. It is massive and thick‑bodied, lacks a ···

Minke Whale

Balaenoptera acutorostrata (common/northern minke whale) / Balaenoptera bonaerensis (Antarctic minke whale)

CetaceaOften reported lifespan is up to about 50 years.

“Minke whale” is a widely used common name for the smallest and most widespread rorquals in the family Balaenopteridae. In many ···

Longmans Beaked Whale

Indopacetus pacificus

CetaceaLifespan is poorly known and is often reported as unknown due to the rarity of encounters.

Longman’s beaked whale (Indopacetus pacificus)—also called the “tropical bottlenose whale” or “Indo‑Pacific beaked whale”—···

Killer Whale

Orcinus orca

CetaceaMales average ~30 years (up to at least ~60); females average ~50 years (up to at least ~90).

The killer whale (Orcinus orca), also known as the orca, is the largest member of the oceanic dolphin family and one of the ocean’···

Humpback Whale

Megaptera novaeangliae

CetaceaLifespan is measured in decades and can approach or exceed ~80 years under favourable conditions.

The humpback whale (Megaptera novaeangliae) is one of the best‑known large baleen whales, famous for its very long pectoral fins,···

Hectors Beaked Whale

Mesoplodon hectori

CetaceaPoorly known; likely several decades, but age at maturity and calving interval are not well established.

Hector’s beaked whale (Mesoplodon hectori) is one of the least-known whales on Earth. It is a deep‑diving beaked whale from the ···

Ginkgo-toothed Beaked Whale

Mesoplodon ginkgodens

CetaceaLikely measured in decades (as with many beaked whales), but precise estimates are uncertain due to limited long-term data.

The ginkgo-toothed beaked whale (Mesoplodon ginkgodens) is an elusive deep-diving toothed whale in the beaked whale family (Ziphii···

False Killer Whale

Pseudorca crassidens

CetaceaCan live for many decades; females often live longer than males, and some individuals may exceed 60 years.

The false killer whale (Pseudorca crassidens) is a large oceanic dolphin with a sleek dark body, a blunt rounded head and no obvio···

Cuviers Beaked Whale

Ziphius cavirostris

CetaceaLongevity is measured in decades and is often suggested to be around 40 years or more, with sexual maturity reached after several years.

Cuvier’s beaked whale (Ziphius cavirostris) is one of the world’s most widespread—and most elusive—beaked whales. It is strong···

Common Dolphin

Delphinus delphis

CetaceaWild lifespan is commonly around 20–25 years, with some individuals living longer.

The common dolphin usually refers to the short-beaked common dolphin, Delphinus delphis. It is famous for its speed, spectacular l···

Bottlenose Dolphin

Tursiops truncatus

CetaceaWild bottlenose dolphins commonly live 30–40 years, and some individuals, especially females, may reach over 50 years; lifespans in captivity can sometimes be longer.

The bottlenose dolphin (most commonly referring to the common bottlenose dolphin, Tursiops truncatus) is one of the best-known dol···

Blainvilles Beaked Whale

Mesoplodon densirostris

CetaceaLongevity is estimated at around 30–40 years based on tooth and bone growth studies.

Blainville's beaked whale (Mesoplodon densirostris) is a medium-sized deep-diving toothed whale in the family Ziphiidae. It is···

Arnouxs Beaked Whale

Berardius arnuxii

CetaceaExact longevity is unknown, but they are presumed to live for several decades, similar to other large beaked whales.

Arnoux's beaked whale (Berardius arnuxii) is a large beaked whale in the family Ziphiidae and one of the least-known cetaceans···

Andrews Beaked Whale

Mesoplodon bowdoini

CetaceaExact longevity is unknown, but Andrews' beaked whales are presumed to live for several decades, similar to other medium-sized beaked whales.

Andrews' beaked whale (Mesoplodon bowdoini) is a medium-sized, extremely poorly known beaked whale in the family Ziphiidae. It···

Māui Dolphin

Cephalorhynchus hectori maui

Cetaceac. 18–25 years (estimated)

Māui dolphin (Cephalorhynchus hectori maui) is a tiny coastal subspecies of Hector’s dolphin,restricted to the west coast of New···

Capybara

Hydrochoerus hydrochaeris,Paraguayan capybara, Uruguayan capybara

Cetacea6-12 Year

水豚这种动物我们虽然不常见，但是水豚的长相很可爱，而且对人类很友好，水豚喜欢生活在比较潮湿的地方，因为它们离不开水，而它们可爱的外···

porpoise

Cetacea10-20years

The porpoise (Phocoena phocoena in Latin), also known as porpoise, is the most common toothed whale in the North and Baltic Seas.P···

Sotalia fluviatilis

South American long-beaked dolphin, Amazon River white-sided dolphin

CetaceaNo verification information

Tucuxi dolphin (scientific name: Sotalia fluviatilis) is also known as tucuxi in English. There is no subspecies.Although they may···

Heaviside's dolphin

Cephalorhynchus heavisidii

CetaceaAbout 20 years

Haviside's dolphin (scientific name: Cephalorhynchus heavisidii) is called Haviside's dolphin in foreign language, and has···

Cephalorhynchus eutropia

black dolphin, black dolphin, Chilean dolphin

CetaceaNo verification information

Chilean dwarf dolphin (scientific name: Cephalorhynchus eutropia) is also known as Chilean Dolphin and Black dolphin in foreign la···

Cephalorhynchus commersonii

Black and white dolphin, panda dolphin, Connor's dwarf dolphin

Cetacea10-25years

The spotted beaked dolphin is the common name of Commerson's dolphin (scientific name: Cephalorhynchus commersonii), also know···

Cephalorhynchus hectori

Hector's dolphin, Atlantic black and white dolphin, white-headed dolphin, New Zealand dolphin, white-headed beaked dolphin, Hector's dwarf dolphin

CetaceaNo verification information

New Zealand black and white dolphins (scientific name: Cephalorhynchus hectori) are called Hector's Dolphin and Dolphin in for···

No matching animals on this page.