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.

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

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!

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.

Many of us have felt the painful bite of the Twin-lobed deer-fly (a 'horse-fly') while out walking in damp grasses or woods. But mostly, it prefers to feed on the blood of cows and…