The blue whale, known scientifically as Balaenoptera musculus, is the largest animal ever known to have existed on Earth. This marine mammal surpasses even the largest dinosaurs in sheer size.
The Scale of a Leviathan
Blue whales can reach astonishing lengths, with confirmed records showing individuals up to 29.9 meters (98 feet) long, and historical reports indicating even larger specimens of 33.58 meters (110 feet). To visualize this immense length, consider it comparable to three school buses lined up end-to-end. These giants can weigh as much as 199 metric tons (219 short tons). This mass is roughly equivalent to the weight of 25 to 50 adult elephants.
The blue whale’s internal anatomy includes its heart, the largest of any animal on Earth. This organ is approximately the size of a small car and can weigh around 180 to 270 kilograms (400 to 600 pounds). This heart beats once every ten seconds, circulating approximately 220 liters (60 gallons) of blood with each pump. Its sounds can be detected from 3 kilometers (2 miles) away. The blue whale’s tongue weighs between 4.5 to 6.8 metric tons (10,000 to 15,000 pounds), comparable to the weight of a single African elephant.
Feeding on the Smallest Prey
Despite its size, the blue whale sustains itself by consuming tiny, shrimp-like crustaceans called krill. These whales are filter-feeders, using a strategy called lunge-feeding. They possess hundreds of baleen plates, comb-like structures made of keratin, which hang from their upper jaws instead of teeth.
During lunge-feeding, a blue whale accelerates, then opens its mouth to engulf water and krill. Its expandable throat pouch inflates, allowing it to take in a large amount. The whale then uses its tongue to push the water out through the baleen plates, trapping the krill inside. A single blue whale can consume up to four metric tons of krill per day, undertaking hundreds of lunges to meet its nutritional needs.
Worldwide Habitat and Communication
Blue whales inhabit all of the world’s oceans, with populations found from polar regions to the equator, except for the Arctic Ocean. They undertake annual migrations, traveling from colder feeding grounds in summer to warmer waters near the tropics for breeding in winter. These migratory journeys can span thousands of miles, covering up to 6,400 kilometers (4,000 miles).
Underwater, blue whales communicate using low-frequency vocalizations, ranging from about 8 to 25 Hertz. These sounds are among the loudest produced by any animal on Earth, reaching up to 188 decibels, surpassing the volume of a jet engine. Such low-frequency calls can travel for hundreds, even thousands of miles through the ocean, allowing whales to communicate across vast distances.
Conservation and Modern Threats
Historically, blue whales faced population declines due to commercial whaling during the 19th and 20th centuries. This period pushed the species to the brink of extinction, with Antarctic populations plummeting from an estimated 125,000 individuals to as few as 3,000 by 2018. While commercial whaling for blue whales ceased globally in 1966, their recovery has been slow.
Presently, blue whales are classified as endangered on the IUCN Red List, with certain subspecies facing critically endangered designations. They continue to confront several modern threats that impede their recovery. Primary concerns include collisions with large ships and entanglement in various types of fishing gear. Underwater noise pollution from human activities and the impacts of climate change on their krill food sources also pose ongoing challenges.