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 fully aquatic marine mammal belonging to the order Cetacea. Unlike fish, whales are warm-blooded, breathe air through blowholes, give live birth, and nurse their young with milk. There are approximately 90 species of cetaceans, ranging from the 5-foot vaquita porpoise to the 100-foot blue whale - the largest animal ever to exist on Earth.

Whale Classification

Whales are divided into two main groups:

Suborder	Common Name	Key Features	Examples
Mysticeti	Baleen Whales	Filter feeders with baleen plates	Blue whale, humpback, gray whale
Odontoceti	Toothed Whales	Have teeth, use echolocation	Sperm whale, orca, dolphins

What Makes a Whale a Mammal?

Whales share all defining characteristics of mammals:

Mammalian Trait	How Whales Display It
Warm-blooded	Maintain body temperature of 97-99°F (36-37°C)
Breathe air	Surface to breathe through blowholes
Live birth	Calves born fully formed, tail-first
Nurse young	Produce fat-rich milk (35-50% fat content)
Have hair	Sparse hair follicles, especially on head
Three ear bones	Inherited from land mammal ancestors

Types of Whales

Baleen Whales (Mysticeti) - 15 Species

Family	Species	Size Range	Diet
Balaenopteridae	Blue, fin, humpback, minke, sei, Bryde’s	25-100 ft	Krill, small fish
Balaenidae	Right whales, bowhead	45-60 ft	Copepods, krill
Eschrichtiidae	Gray whale	40-50 ft	Bottom sediment organisms
Neobalaenidae	Pygmy right whale	20 ft	Copepods

Toothed Whales (Odontoceti) - 75+ Species

Family	Examples	Size Range	Diet
Physeteridae	Sperm whale	35-60 ft	Giant squid, fish
Delphinidae	Orca, dolphins	6-26 ft	Fish, marine mammals
Ziphiidae	Beaked whales	13-40 ft	Squid, deep-sea fish
Phocoenidae	Porpoises	4-7 ft	Fish, squid
Monodontidae	Beluga, narwhal	13-18 ft	Fish, squid, shrimp

Whale Anatomy

Body Part	Function	Unique Adaptations
Blowhole	Breathing	1 (toothed) or 2 (baleen) nostrils on top of head
Fluke	Propulsion	Horizontal tail moved up and down
Dorsal Fin	Stability	10,000-25,000 worldwide greatly; absent in some species
Pectoral Fins	Steering	Modified forelimbs with finger bones
Blubber	Insulation, energy	2-12 inches thick depending on species
Baleen/Teeth	Feeding	Baleen plates or teeth (never both)

Whale Evolution

Whales evolved from land-dwelling ancestors:

Time Period	Stage	Key Development
50 million years ago	Pakicetus	Wolf-sized land mammal, ancestor
47 million years ago	Ambulocetus	”Walking whale,” semi-aquatic
42 million years ago	Rodhocetus	Reduced limbs, more aquatic
40 million years ago	Basilosaurus	Fully aquatic, elongated body
35 million years ago	Early cetaceans	Baleen and toothed lines diverge
Present day	Modern whales	90+ highly specialized species

Frequently Asked Questions

Are dolphins and porpoises whales?

Technically, yes. Dolphins and porpoises are toothed whales belonging to the suborder Odontoceti. The killer whale (orca) is actually the largest dolphin species. The terms “whale,” “dolphin,” and “porpoise” are common names, not strict scientific categories. Learn more about whether dolphins are whales.

What’s the difference between a whale and a fish?

Whales and fish are fundamentally different:

• Whales are warm-blooded mammals that breathe air, give live birth, and have horizontal tail flukes
• Fish are cold-blooded, breathe through gills, mostly lay eggs, and have vertical tail fins

What is the largest whale species?

The blue whale is the largest whale and the largest animal ever to exist, reaching lengths of 100+ feet and weights of 200+ tons. Learn more about how long blue whales are.

What is the smallest whale?

The vaquita porpoise is the smallest cetacean at about 5 feet long, though it’s critically endangered with fewer than 10 individuals remaining. Among species commonly called “whales,” the dwarf sperm whale at 8-9 feet is smallest.

How long do whales live?

Lifespans vary by species:

• Bowhead whale: 200+ years (longest-lived mammal)
• Blue whale: 80-90 years
• Humpback whale: 45-50 years
• Orca: 50-80 years

Whale Size Comparison

Species	Length	Weight	Classification
Blue Whale	80-100 ft	200-300,000 lbs	Baleen
Fin Whale	70-80 ft	100-140,000 lbs	Baleen
Sperm Whale	50-60 ft	80-100,000 lbs	Toothed
Humpback Whale	48-62 ft	50-80,000 lbs	Baleen
Orca	20-26 ft	8-12,000 lbs	Toothed (dolphin)

Ecological Importance

Whales play vital roles in ocean ecosystems:

Ecological Role	Description
Nutrient cycling	Whale feces fertilize surface waters
Carbon sequestration	Whale bodies sink carbon to ocean floor
Prey population control	Regulate fish and krill populations
Ecosystem engineers	Create feeding opportunities for other species
Tourism value	Support billion-dollar whale watching industry

Conservation Status

Status	Species Examples
Critically Endangered	North Atlantic right whale, vaquita
Endangered	Blue whale, fin whale, sei whale
Vulnerable	Sperm whale
Least Concern	Minke whale, humpback (recovering)

Learn more about why blue whales are endangered and explore what is the biggest whale in the world.

Related Questions

• Are Whales Mammals?
• How Long is the Blue Whale?
• Is a Dolphin a Whale?
• What is the Biggest Whale in the World?