The largest animal that has ever lived — bigger than any dinosaur. Adults reach 100 feet and 200 tons; their hearts alone are the size of a small car. Pre-whaling populations of ~250,000 are now down to perhaps 10,000–25,000.

Also called: Sulphur-bottom Whale

Native status: Native; endangered

§ Quick facts

SizeAdult length 24–30 m (80–100 ft); the longest verified blue whale was 33 m (108 ft)
Weight130–150 metric tons (290,000–330,000 lb) — heaviest animal ever
Lifespan80–90 years estimated; one recorded individual ~110 years
OrderCetacea
FamilyBalaenopteridae

§ Encyclopedia

The blue whale is a species of baleen whale and the largest marine mammal in the rorqual family Balaenopteridae. Reaching a maximum confirmed length of 29.9–30.5 m (98–100 ft) and weighing up to 190–200 t, it is the largest animal known to have ever existed. The blue whale's long and slender body can be of various shades of greyish-blue on its upper surface and somewhat lighter underneath. Four subspecies are recognized: B. m. musculus in the North Atlantic and North Pacific, B. m. intermedia in the Southern Ocean, B. m. brevicauda in the Indian Ocean and South Pacific Ocean, and B. m. indica in the Northern Indian Ocean. There is a population in the waters off Chile that may constitute a fifth subspecies.

Source: Wikipedia — Blue whale Licensed under CC BY-SA 4.0

§ Identification

Field marks. Mottled blue-gray; tiny dorsal fin set far back; massive U-shaped head visible at surfacing. Spout column reaches 9 m (30 ft).

Similar species. Fin Whale (smaller, asymmetric jaw coloration). Sei Whale (smaller still, taller dorsal).

Voice. Low-frequency "song" — 10–40 Hz pulses below human hearing range; can travel over 1,000 km.

§ Diet & behavior

Diet. Almost exclusively krill — small shrimp-like crustaceans — consumed at 4 metric tons per day in feeding season.

Behavior. Migrates seasonally between high-latitude feeding grounds and low-latitude breeding grounds. Solitary or in loose pairs. Vocalizations carry hundreds of km underwater.

§ Range

All the world's oceans

§ Habitat

Open ocean, polar to tropical

§ Threats

Vessel strikes, ocean noise, krill decline from climate change, entanglement.

§ Conservation status

According to the IUCN Red List, the blue whale is currently classified as Endangered.

§ What helps

Support 10-knot vessel speed limits in feeding areas. Reduce single-use plastics. Choose krill-free seafood/supplements.

Support our work More ways to help

§ Further reading

§ Sources cited

  • NOAA Fisheries
  • IWC Cetacean Status
  • Cascadia Research
  • IUCN Red List 2018