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.

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.

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…