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!

The much-loved robin is a garden favourite and one of our most familiar birds, adorning Christmas cards every year. It is very territorial, however, and will defend its post with surprising…

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.

Look for the Yellow water-lily in still and slow-moving water, such as ponds, ditches, lakes and canals. Its lily pads and cupped, yellow flowers float at the water's surface.

Selfheal is a low-growing, creeping plant that likes the short turf of grasslands, roadside verges or even lawns. Its clusters of violet flowers appear in summer.

Sea-buckthorn is a spiny, thicket-forming shrub of sand dunes. It's native to the east coast of England but considered an invasive species elsewhere. It is most obvious in autumn when it is…