The speed of vessels operating near where killer whales live is the most influential factor—even more so than size—in determining how much noise reaches the endangered animals.

It’s difficult enough to see things in the dark, but if you’re a hummingbird-sized hawkmoth you also have to juggle hovering in midair while tracking a flower that’s moving in the wind.

Toddlers as young as two understand that the noises they make can affect people around them—and know how to adapt the loudness of the sounds they make depending on what they’re doing and where they are.