What Is A Whale?

Quick Facts

Attribute	Details
Type	Marine mammal
Family	Cetacea
Habitat	Oceans worldwide
Conservation	Protected in most countries
Research Status	Ongoing scientific study

The Short Answer

A whale is a marine mammal belonging to the order Cetacea—a group that also includes dolphins and porpoises. Unlike fish, whales breathe air through lungs, give live birth, nurse their young with milk, and maintain a constant body temperature. There are approximately 90 species of cetaceans, with whales ranging from the 8.5-foot dwarf sperm whale to the 100-foot blue whale—the largest animal ever to exist on Earth.

What Makes a Whale a Whale?

Whale Characteristics vs. Fish

Characteristic	Whales	Fish
Breathing	Lungs (air)	Gills (water)
Body temperature	Warm-blooded	Cold-blooded
Reproduction	Live birth	Usually eggs
Nursing	Mother’s milk	None
Tail movement	Horizontal (up-down)	Vertical (side-to-side)
Skeleton	Bone	Often cartilage
Hair	Yes (some)	No
Blubber	Thick layer	None

These fundamental differences place whales firmly in the mammal category, despite their fish-like appearance. Learn more at is a whale a fish.

Key Mammalian Features in Whales

Feature	Description	Example
Lungs	Must surface to breathe	Blow every 10-20 minutes
Mammary glands	Produce milk for calves	150 gallons/day (blue whale)
Hair	Reduced but present	Whiskers on some species
Warm blood	~37°C body temperature	Maintained in freezing water
Live birth	No eggs	10-17 month gestation
Parental care	Extended nursing period	6 months to 2 years

The Two Main Types of Whales

Baleen Whales (Mysticeti)

Species	Maximum Size	Diet	Notable Feature
Blue Whale	100 ft (large sizes)	Krill	Largest animal ever
Fin Whale	85 ft (26m)	Krill, fish	Second largest
Humpback Whale	62 ft (19m)	Krill, fish	Complex songs
Gray Whale	49 ft (15m)	Amphipods	Longest migration
Right Whale	60 ft (18m)	Copepods	Critically endangered
Minke Whale	35 ft (11m)	Fish, krill	Most common baleen

Baleen whales filter feed using baleen plates—comb-like structures made of keratin (the same protein as human fingernails) that strain small prey from seawater.

Toothed Whales (Odontoceti)

Species	Maximum Size	Diet	Notable Feature
Sperm Whale	67 ft (20m)	Squid	Largest toothed whale
Orca (Killer Whale)	32 ft (10m)	Varied	Top predator
Beluga Whale	18 ft (5.5m)	Fish	White coloration
Narwhal	18 ft (5.5m)	Fish, squid	Spiral tusk
Pilot Whale	25 ft (7.6m)	Squid	Highly social
Beaked Whales	15-40 ft	Squid	Deep divers

Toothed whales actively hunt individual prey using echolocation—biological sonar that allows them to “see” with sound.

Whale Evolution: From Land to Sea

Evolutionary Timeline

Era	Years Ago	Ancestor	Key Features
Early	50 million	Pakicetus	Wolf-like, land-dwelling
Transitional	47 million	Ambulocetus	”Walking whale,” semi-aquatic
Aquatic	41 million	Rodhocetus	Small legs, aquatic lifestyle
Marine	38 million	Basilosaurus	Fully aquatic, 60 ft long
Modern	35 million	Early mysticetes/odontocetes	Two lineages diverge
Present	0	Modern whales	90 species worldwide

Research from the Natural History Museum shows that whales evolved from land-dwelling ancestors related to modern hippopotamuses. Vestigial leg bones inside whale bodies provide evidence of this terrestrial origin.

Evidence of Land Ancestry

Evidence	Description	Location
Vestigial pelvis	Tiny hip bones	Inside body cavity
Finger bones	Five digits in flippers	Whale flippers
Fetal hair	Embryos have body hair	Developing fetuses
Nostrils position	Migrated from snout to top	Blowhole evolution
Hindlimb buds	Appear then disappear in embryos	Developmental studies

Whale Distribution Worldwide

Where Whales Live

Ocean Region	Common Species	Season
Antarctic	Blue, humpback, orca	Summer feeding
Arctic	Beluga, narwhal, bowhead	Year-round
North Pacific	Gray, humpback, orca	Year-round/migration
North Atlantic	Right whale, humpback	Year-round/migration
Tropical	Sperm, pilot, beaked	Year-round
Temperate	Specific prey items	Migration corridors

Many whale species undertake long migrations between cold, food-rich feeding grounds and warm breeding waters—gray whales travel up to 12,000 miles annually.

Frequently Asked Questions

What is the difference between a whale and a dolphin?

Scientifically, dolphins are a type of toothed whale—both belong to the order Cetacea and suborder Odontoceti. The distinction is largely arbitrary: “dolphins” typically refers to smaller species with beak-like snouts, while “whales” refers to larger species. Confusingly, orcas (killer whales) are actually the largest dolphins, and pilot whales are also dolphins despite being called whales.

How do whales breathe underwater?

Whales don’t breathe underwater—they must surface regularly to breathe air. Unlike fish with gills, whales have lungs. Their blowholes are nostrils that moved to the top of the head through evolution. Whales can hold their breath for varying times: 10-20 minutes for most species, up to 90 minutes for sperm whales during deep dives.

What is the smallest whale?

The smallest whale is the dwarf sperm whale (Kogia sima), reaching only 8.5 feet (2.6 meters) and weighing about 600 pounds. If we include dolphins (which are technically toothed whales), the smallest cetacean is Maui’s dolphin at 4 feet (1.2m). See how long whales are for size comparisons.

What is the largest whale?

The blue whale is the largest whale—and the largest animal ever to exist on Earth, including all dinosaurs. Blue whales reach 100 feet (large sizes) in length and 200 tons in weight. Learn more at what’s the biggest whale.

Are killer whales actually whales?

Taxonomically, killer whales (orcas) are dolphins, not true whales—they belong to the family Delphinidae (oceanic dolphins). However, dolphins are toothed whales (Odontoceti), so orcas are whales in the broader sense. The common name “killer whale” predates modern taxonomy. Learn more at are killer whales whales.

Whale Intelligence and Social Life

Cognitive Abilities

Ability	Evidence	Species
Self-recognition	Mirror test passed	Orcas, bottlenose dolphins
Tool use	Sponge protection for foraging	Bottlenose dolphins
Cultural learning	Hunting techniques passed down	Orcas, humpbacks
Language-like communication	Complex vocalizations	Orcas, sperm whales
Problem solving	Novel solutions to challenges	Multiple species

Social Structures

Structure	Description	Species
Matrilineal pods	Mother-led family groups	Orcas, pilot whales
Female groups	Adult females with young	Sperm whales
Loose associations	Temporary feeding groups	Baleen whales
Mating aggregations	Seasonal gatherings	Right whales, humpbacks

Learn more about whale societies at what is a group of whales called.

Conservation Status

Current Whale Populations

Species	IUCN Status	Population	Trend
Blue Whale	Endangered	10,000-25,000	Increasing
North Atlantic Right Whale	Critically Endangered	~350	Decreasing
Sperm Whale	Vulnerable	300,000	Stable
Humpback Whale	Least Concern	84,000	Increasing
Gray Whale	Least Concern	27,000	Stable
Fin Whale	Vulnerable	100,000	Increasing

The International Whaling Commission’s 1986 commercial whaling moratorium has allowed many populations to recover, though some species remain critically endangered.

For more whale information, explore whether whales are mammals, whale sizes, and the biggest whale species.

Related Questions

• Is a Whale a Fish?
• Is a Whale Mammal?
• How Long is a Whale?
• Whats the Biggest Whale?