“The blue whale is the largest animal ever to have lived”, according to National Geographic’s Education Blog, and experts across the globe agree. They are bigger than any known dinosaur and far bigger than the largest land animal, the African bush elephant. Blue whales, Balaenoptera musculus, make their homes in the planet’s vast open oceans where most migrate thousands of miles annually to feed, mate, and raise calves.
There are 4 recognized subspecies, the largest being the Antarctic blue whale. There is also the Indian Ocean blue whale, Northern blue whale, and Pygmy blue whale.
So How Big Is A Blue Whale?
Length
The longest confirmed measurement of a blue whale is 110 feet (33.5 meters), making them the longest animals alive today. That is approximately the length of
- 5 African bush elephants
- 1 Argentinosaurus
- 1 Boeing 737
- 1 NBA basketball court
African bush elephants are currently the largest land animals at 24 feet (7.3 meters) long. The Argentinosaurus is the largest dinosaur known to have roamed the planet. These herbivores were estimated to reach about 110 feet (33.5 meters) in length.
Weight
Scientists estimate that blue whales can weigh up to 440,000 pounds (199,580 kg or 220 US tons), making them the heaviest animal ever. One blue whale is approximately the weight of
- 40 African bush elephants
- Almost 3 Argentinosauruses
- 4 Boeing 737s
- 3300 people
A blue whale on land would be crushed by its own weight. Fortunately, in the ocean, the saltwater gives it the buoyancy it needs to navigate the waters gracefully. An adult male African bush elephant can weigh up to 13,300 pounds (6,040 kg) and the Argentiniosaurus was estimated to weigh 154,000 pounds (70000 kg), both of which pale in comparison to the blue whale.
Diet
To maintain a healthy body mass, a blue whale needs to consume large amounts of food. They feed primarily on krill, which are small shrimp-like invertebrates, but they sometimes also eat small fish and other tiny crustaceans. This diet is unique because
- a blue whale can eat 4 tons (3629 kilograms) of krill per day in summer (about 40 million individual krill)
- this is the biggest size difference between predator and prey in the animal kingdom
- a blue whale’s tongue weighs a record-breaking 8,800 pounds (3992 kilograms)
The blue whale is one of many baleen whales. They feed in polar waters in the summer, where the krill are abundant. They take large volumes of water into their mouths and use their powerful tongues to expel the water through the baleen plates that hang from their upper jaws. The bristles on the baleen plates trap the krill, which the whales can then swallow.
Reproduction
Marine biologists are still studying and learning about blue whale reproduction. It is estimated that a cow will give birth every 2 to 3 years and that gestation is 10 to 12 months long. Like humans, blue whales are mammals. They breathe air, have live births, and nurse their babies. A blue whale calf is the largest newborn on earth. It can be as long as 27 feet (8.2 meters) and can weigh 3 tons (2721.6 kilograms) at birth. These babies will nurse for several months before they wean themselves and are ready to live on their own. Until that time, they will
- drink 100 gallons (379 liters) of mother’s milk per day
- gain 200 pounds (90 kilograms) per day or 8 pounds (3.6 kilograms) per hour
- grow 1.5 inches (3.8 centimeters) per day
At weaning, the calf is approximately 8 months old, 52 feet (16 meters) long, and weighs about 23 tons (20900 kilograms). They will reach sexual maturity between 5 and 15 years of age.
Cardiovascular
Scientists are still making discoveries about the cardiovascular system of blue whales. In heart and lung size, blue whales are again at the top of the animal kingdom.
- Heart size – about 5 feet tall by 5 feet long by 4 feet wide (1.5 x 1.5 x 1.2 meters)
- Heart weight – about 400 pounds (180 kilograms)
- Heart size is about 14 times the size of an African bush elephant’s heart
- The average heart rate is just 6 beats per minutes, the slowest of any mammal
- The lung capacity is 1320 gallons (5000 liters)
The heart rate of a blue whale can go as low as 2 beats per minute during a foraging dive and as high as 37 beats per minute when it surfaces for air. Their massive lung volume helps keep their blood oxygenated during long dives.
Other Blue Whale facts
Blue whales don’t break the record in every category, but it’s still worth noting some other amazing feats
- Speed – they can reach up to 30 miles per hour (48.3 km/h) and swim as slow as 5 mph (8km/hr) when they are sleeping
- Vocalization – the sounds of blue whales can reach 188 decibels, which is louder than a jet engine, and can be heard by other whales hundreds of miles away
- Migration – many blue whales travel thousands of miles per year from polar waters in summer for feeding to tropical waters in winter for mating and calving
Summary
The blue whale’s record-breaking size makes it fascinating to study and compare to other animals and humans. Just as intriguing is how much we still don’t know about them, including details about populations, migration, and feeding.
Blue whales are currently classified as endangered under the Endangered Species Act and protected under the Marine Mammal Protection Act. Whaling practices in the early 1900s wiped out 97-99% of most populations. Current protections have allowed for a minimal rebound, but human threats do still exist, like vessel strikes, fishing gear entanglement, and climate change. Continued efforts by environmentalists to reduce the impact of humans on the planet can improve life for the blue whale and other endangered animals.
References:
-American Cetacean Society; “Blue Whale”; accessed April 7, 2021; ACS Online; https://www.acsonline.org/blue-whale
-Carylsue; 08/31/2015; “How Big is a Blue Whale’s Heart”; National Geographic Education Blog;https://blog.education.nationalgeographic.org/2015/08/31/how-big-is-a-blue-whales-heart/
-Dimery, Rob; February 18, 2019; “The record-setting anatomy of the blue whale: a look inside the largest animal in the world”; Guinness World Records; https://www.guinnessworldrecords.com/news/2019/2/record-setting-anatomy-of-the-blue-whale-a-look-inside-the-largest-animal
-Monterey Bay Aquarium; “Blue Whale”; accessed April 7, 2021; Monterey Bay Aquarium; https://www.montereybayaquarium.org/animals/animals-a-to-z/blue-whale
-National Oceanic and Atmospheric Association; “Blue Whale”; accessed April 7, 2021; NOAA Fisheries; https://www.fisheries.noaa.gov/species/blue-whale
-Oregon State University; “Blue Whale”; accessed April 7, 2021; OSU Whale Telemetry Group; https://mmi.oregonstate.edu/wtg/research-projects/blue-whale
