A common and diminutive fish, the minnow can be found in freshwater streams, rivers and lakes across the country. Look out for the dark stripe along its flank and the red bellies of the males.

A diminutive but aggressive predator, the three-spined stickleback hunts tadpoles and small fish. It is also known for fiercely protecting its nest of eggs until they hatch. Look for it in ponds,…

The alder fly is a blackish invertebrate, with delicately veined wings that it folds over its body like a tent. It can be found near ponds and slow-flowing rivers; the larvae living in the silt at…

The sinuous otter is an excellent swimmer and can be seen hunting in wetlands, rivers and along the coast - try the west coast of Scotland, West Wales, the West Country or East Anglia for the best…

The green sandpiper is a very rare breeding bird in the UK, and is mainly seen on migration in autumn. Look out for it feeding around marshes, flooded gravel pits and rivers. It even likes sewage…

Reed sweet-grass is a towering grass with large, loose flower heads that can be found on marshy ground near rivers, streams and ponds. It can become invasive, but does shelter various aquatic…

These non-native limpets arrived from America in the 19th century and are now widespread in the UK. They form stacks and have a specially adapted shell which, when flipped upside down, looks like…