It's easy to see where the blue shark got its name from. These sleek, elegant sharks have beautiful metallic blue backs which provide brilliant camouflage out in the open ocean.

The rare Adonis blue can be spotted on sunny chalk grasslands throughout summer. Males are a dazzling sky-blue in colour, while females are duller brown.

Often confused with the larger but similarly shaped lion’s mane jellyfish, the blue jellyfish can be colourless when young and develop a striking blue-purple bell as it matures.

Despite its name, the large blue is a fairly small butterfly, but the largest of our blues. It was declared extinct in 1979, but reintroduced in the 1980s and now survives in southern England.

A familiar garden bird, the blue tit can be seen around bird tables and feeders, as well as in woodlands and parks. Listen out for its trilling, 'tsee-tsee-tsee' song. It is smaller than…