A blue whale's call can be heard by other whales up to 1,600 kilometers (1,000 miles) away.
Why it is true
Blue whales produce incredibly loud, low-frequency sounds that travel efficiently through water, allowing them to communicate across entire ocean basins.
Source: Marine Biology
Would you rather be asked first?
This is the reading side of the site, so the answer is in the sentence above — that is the whole point of it. Test yourself works the other way round: the question comes on its own, and the fact and the explanation only appear once you have answered.
Related facts
Animals
Chameleons change color primarily to communicate and regulate temperature, not just to camouflage.
Animals
A wolf's howl can be heard by other wolves up to 10 kilometers away.
Animals
Dolphins develop unique whistles that work like names and use them to call each other.
Animals
The tongue of a blue whale weighs approximately as much as an elephant.
