There are basically four types of algae, based on their color: green, blue-green, red, and brown. Green and blue-green algae are found in freshwater as well as saltwater. Red and brown algae are found ...

Have you ever seen brown or green goo floating on a river or in the ocean? Or have you noticed how the walls of a fish tank sometimes turn green and slimy? These are all examples of algae—but there is ...