Water-cress has become so popular as a salad addition that it is now cultivated on a wide scale. In the wild, it grows in shallow, fast-flowing streams and is an indicator of clean water.

This worm builds its own home out of bits of shell and sand. It can be spotted on the shore all around the UK.

Look for the White water-lily in still and slow-moving water, such as ponds, ditches, lakes and canals. Its lily pads and massive, white flowers float at the water's surface.

Look for the Yellow water-lily in still and slow-moving water, such as ponds, ditches, lakes and canals. Its lily pads and cupped, yellow flowers float at the water's surface.

The pretty-in-purple Pasqueflower is now a rare plant in the UK, restricted to just a few chalk and limestone grasslands. Steeped in legend, it flowers at Easter, so is known as the 'anemone…

Found in ponds and marshes, the fragile look of the Common water-measurer belies its fierce nature. A predator of small insects, it uses the vibrations of the water's surface to locate its…

This huge gull can be seen around most of the UK's coasts in summer, with some venturing inland in winter.