Living up to its name, the bullhead has a characteristically large, flattened head and a tapering body. Look out for it in fast-flowing, stony rivers and streams.

This striking black-and-white moth flies during the day in open woodlands, moorlands, and bogs. It's most common on Scottish moors.

Field wood-rush is a short rush that forms tufts in grassy places, such as lawns, parks and downlands. A defining characteristic is its leaf-like leaves that are fringed with long, white hairs.…

The chocolate-brown, plump dipper can often be seen bobbing up and down on a stone in a fast-flowing river. It feeds on underwater insects by walking straight into, and under, the water.

A handsome fish, the tench has olive-green flanks, powerful fins and distinctive red eyes. It can be found in lowland lakes and slow-flowing rivers around the UK.

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.