Animals, from worms and sponges to jellyfish and whales, contain anywhere from a few thousand to tens of trillions of nearly ...

In this article, you’ll learn how eukaryotic cells operate, providing a solid foundation for understanding how life functions ...

Animal and plant cells have different energy-producing structures inside them. For animals, that’s mitochondria , which convert chemical energy from food into a form that our cells can use.

When animals defecate, they shed living cells from their intestines, and these can be found on the outside of the dung, says Williams, a professor of fertility and reproductive health.