The Blue Whale (Balaenoptera musculus) holds the undisputed title as the largest animal on Earth, surpassing all known species, living or extinct. This massive marine mammal sets the standard for scale in the animal kingdom. Its size is a testament to the evolutionary possibilities of life supported by the buoyancy of the ocean. The creature’s existence showcases the extremes of biological engineering and mass.
Defining the Scale of the Blue Whale
An adult Blue Whale can reach an average length of 82 to 105 feet, with the longest individuals confirmed at nearly 98 feet, which is longer than three school buses lined up end-to-end. The average blue whale weighs between 100 and 150 tons, with some recorded specimens reaching up to 190 tons.
Its internal anatomy is built to service this massive body. The heart of a Blue Whale is the largest in the animal kingdom, weighing between 400 and 600 pounds and being approximately the size of a small car. The tongue alone can weigh as much as an African elephant, around 4 to 6.8 tons. The main artery, the aorta, measures over nine inches in diameter.
Sustaining Immense Size: Diet and Feeding
Maintaining this body mass relies on a specialized feeding strategy. Blue Whales are filter feeders, relying almost exclusively on tiny, shrimp-like crustaceans called krill. They possess hundreds of baleen plates made of keratin, which hang from the upper jaw and strain food from the ocean water.
The whale employs lunge feeding, rapidly swimming into dense swarms of krill to engulf colossal volumes of water and prey. The throat has an expandable, pleated structure that allows it to take in a volume of water greater than its own body weight. To sustain its size, a single Blue Whale must consume up to 4 tons of krill per day during peak feeding season.
Comparing the Largest Marine Life
While the Blue Whale is the largest animal overall, other creatures hold records in different biological categories.
Largest Fish
The Whale Shark (Rhincodon typus) is the largest fish, reaching lengths of up to 61.7 feet. As a fish, the Whale Shark lacks mammalian characteristics, such as lungs and warm-bloodedness.
Largest Invertebrates
The title of largest invertebrate—an animal without a backbone—is often debated. The Giant Squid (Architeuthis dux) is considered the longest, with tentacles reaching lengths of up to 60 feet. The Colossal Squid (Mesonychoteuthis hamiltoni) is the heaviest, with a confirmed mass of nearly 1,100 pounds. The Lion’s Mane Jellyfish (Cyanea capillata) holds the record for the longest animal due to its trailing tentacles, which can extend over 100 feet in length.