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 tiny gamebird is rarely seen, but its distinctive "wet my lips" call can be heard ringing out over areas of farmland on summer evenings.

Look for the wood warbler singing from the canopy of oak woodlands in the north and west of the UK. Green above, it has a distinctive, bright yellow throat and eyestripe.

Arrowhead is an aquatic plant of shallow water and slow-moving waterways. In bloom over summer, it displays small, white flowers, but it is the arrow-shaped leaves that are most distinctive.

When spotting the pintail in winter, look out for the fabulous, long tail feathers that characterise it. This dabbling duck feeds at the water's surface, rather than diving for food.

The male purple emperor is a stunning butterfly with a brilliant purple sheen. Look for it feeding around the treetops in woodlands, or on damp ground, animal droppings or even carrion in the…

This brown seaweed lives high up on rocky shores, just below the high water mark. Its blades are usually twisted, giving it the name Spiral Wrack.

The rare wildcat is so similar to a domestic tabby that interbreeding is a serious threat to its survival. Although known as the 'tiger of the Highlands', it is shy and elusive, making…