Native oysters are a staple of our seas and our plates - but our love of their taste has lead to a sharp decline all around the UK.

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 slippery butterfish is a common sight in rockpools all around the UK. Look out for the distinctive black spots on their backs that look a lot like eyes!

A pretty, little gull, the kittiwake can be spotted nesting in colonies on clifftops and rock ledges around the UK's coast. It spends the winter out at sea.

The fine, downcurved bill of the treecreeper makes this tit-sized bird unmistakeable. Look out for it in woodlands and parks, literally 'creeping' around tree trunks.

The Glanville fritillary can be spotted on warm days around coastal habitats on the Isle of Wight and the Channel Islands, as well as at a few locations in mainland England.

The purple hairstreak is an elusive butterfly with a brilliant purple sheen. It is entirely reliant on oak trees and can be spotted chasing around the treetops in woodlands and parks.

From grunts and groans, to 'purring' and 'piglet squealing', the water rail is more often heard than it is seen! This shy bird lives in reedbeds and wetlands, hiding among the…

The greenshank breeds on the boggy moors and ancient peatlands of Scotland. But it can be spotted elsewhere in the UK as it passes through on migration - look around lakes, marshes and the coast…

These energetic dolphins are often spotted in large groups which will approach boats, bowriding and leaping alongside. At sea, they can form superpods - huge groups made up of thousands of…

The Leisler's bat flies fast and high near the treetops, but you might also spot it flying around lamp posts, looking for insects attracted to the light.