Blue whale arteries are large enough for humans to swim through and their hearts are the size of cars.
12
A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
23
The oldest known animal in the world was 'Ming' the 405 year old clam, discovered in 2007.
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The sound of a tiger's roar can travel a distance of up to 2 miles (~3 km).
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