The term 'plankton' covers a wide range of animals, from those invisible to the naked eye to others that can be as much as a hundred feet long. The word 'plankton' is taken from the Greek word for 'to wander' and is used to refer to those pelagic forms which are carried about by movements of the water rather than by their own ability to swim. Click on any of the images below to explore some of the different types of plankton - or click on the image to the right to see a selected variety.