Worms in the sea are anything but dull and this fan worm, resembling a Catherine wheel, is a perfect example of the intricate beauty these animals possess.

This little cuttlefish really lives up to its name - it only reaches about 6cm long!

Common alder can be found along riversides, and in fens and wet woodlands. Its exposed roots provide shelter for fish, and its rounded leaves are food for aquatic insects.

The fearsome common backswimmer hunts insects, tadpoles and fish. It uses its oar-like legs to swim upside-down under the water's surface where unsuspecting prey can be found.

The beautiful pink and white bands of a Painted topshell make it easy to see where this little sea snail got its name!

This brilliant red and white sea slug would make the perfect nudibranch for a Christmas card image or perhaps a football team mascot!

The gudgeon is a bottom-dwelling fish, similar to the stone loach, but with only two whisker-like barbels near its mouth. These sensory organs help it to find its prey in the sand and gravel of…

A common and diminutive fish, the minnow can be found in freshwater streams, rivers and lakes across the country. Look out for the dark stripe along its flank and the red bellies of the males.

A diminutive but aggressive predator, the three-spined stickleback hunts tadpoles and small fish. It is also known for fiercely protecting its nest of eggs until they hatch. Look for it in ponds,…

This brown seaweed lives in the lower shore and gets its name from the serrated edges to its fronds.