Britannica Today in History
Day 26 after signup
You could climb inside this animal's heart
Taking “big-hearted” literally.
Why it works
- Lead with a surprising comparison that makes the main fact easy to picture.
- Follow the explanation with a short quiz to give readers another way to engage with the topic.
- Place related articles after the main feature so readers can continue exploring without interrupting the lead story.
How it is built
- Date and masthead
- Featured animal fact
- Supporting explanation
- Animal guessing quiz
Email copy
October 22, 2026 Fact of the Day Mammals A blue whale’s heart is the size of a Harley-Davidson. By Michael Nordine Blue whales, the largest animals to ever exist, are more massive than most of us can fathom. They can reach lengths of more than 100 feet and weigh up to 330,000 pounds, more than twice the weight of any known dinosaur. As such, blue whales need similarly large organs to support their prodigious size — especially their hearts, which are roughly the size of a Harley-Davidson: 5 feet long, 4 feet wide, and about 400 pounds. That makes them the largest blood-pumping organ in the world, more than 14 times the size of an elephant’s heart and 640 times larger than our own. Meet the big animals that have weirdly small body parts Guess the Animal What am I? Hint 1 I’m the third-largest land mammal, but I have a relatively small brain. Hint 2 I secrete my own reddish “sunscreen.” Hint 3 Despite spending my days in water, I can’t swim or float. See the Answer Keep Exploring Mammals How Whales ‘Talk’ Under the Sea Across Species The 10 Biggest Animals on Earth Mammals How Did the Sperm Whale Get Its Name? Was this email forwarded to you? Sign Up Advertise Contact Us Privacy Policy Terms of Use 325 North LaSalle Street, Suite 200, Chicago, IL 60654 If you'd like to unsubscribe from all Animal Facts emails, click here.