Dragging dead fish around reveals super power of mucus

By dragging a bunch of dead fish around, scientists may have uncovered a hidden power of one of biology's most important substances--mucus. And what they found might even help us understand the very dawn of vertebrate life on land. First, it's important to know that fish are covered in a thin layer of mucus. This slimy coating (it is also called a "slime coat") is known to keep fish healthy by warding off pathogens. Scientists have also found some evidence that mucus can reduce drag, helping fish swim through the water more easily.