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.

The ptarmigan is a master of disguise - matching its Highland surroundings perfectly by turning snow-white in winter and rock-grey in summer. It is confined to the mountains of Scotland, so is…

A breeding bird of fast-flowing, upland rivers, the grey wagtail can also be seen in lowland areas, farmyards and even towns in winter.

Our most familiar fern, bracken can be found growing in dense stands on hillsides, moorland, heathland and in woodlands. It is very large and dies back in winter, turning the landscape orangey-…

Forming mats of straight, bright green stems, Common spike-rush does, indeed, look like lots of tightly clustered 'spikes' near the water's edge of our wetland habitats.

The knopper gall wasp produces knobbly red, turning to brown, growths, or 'galls', on the acorns of Pedunculate Oak. Inside the gall, the larvae of the wasp feed on the host tissues, but…

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.

Famed for its tapping in the middle of the night, supposedly heralding tragedy, the Deathwatch beetle is a serious wood-boring pest. In houses, their tunnelling can cause major damage.

The common octopus is a highly intelligent, active predator. It even has a secret weapon - special glands produce a venom that it uses to incapacitate its prey!

Piddocks are a boring bivalve. No, we don't mean dull... we mean that it bores into soft rock, creating a burrow. In fact, they're the opposite of dull - they glow in the dark!

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.