When most mammals go to sleep, they lie their weary heads on a pillow, the ground, or curl up in a ball. From there, they enter a state of rest, usually for several hours at a time. You know that ...

When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. If marine mammals want to sleep, they can't just close their eyes and drift away for the night, ...

Of the roughly 250,000 known marine species, scientists think all ~126 marine mammals emit sounds – the ‘thwop’, ‘muah’, and ‘boop’s of a humpback whale, for example, or the boing of a minke whale.