Bladder campion is so-called for the bladder-like bulge that sites just behind the five-petalled flower - this is actually the fused sepals. Look for it on grasslands, farmland and along hedgerows…

The sessile oak is so-called because its acorns are not held on stalks like those of the familiar English oak. It can be found in woodlands mainly in the north and west of the UK.

Small-spotted catsharks used to be called lesser-spotted dogfish - which might be what you know them best as. It's the same shark, just a different name!

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 rare wildcat is so similar to a domestic tabby that interbreeding is a serious threat to its survival. Although known as the 'tiger of the Highlands', it is shy and elusive, making…

The smaller of our two UK seal species, common seals are also known as harbour seals. Despite being called "Common", they are actually less common than grey seals!

The tightly packed, thistle-like purple flower heads of common knapweed bloom on all kinds of grasslands. Also regularly called black knapweed, this plant attracts clouds of butterflies.

Heather is also called 'ling'. Look for it on our heaths, moors and bogs, where its delicate, loosely arranged pink flowers attract all kinds of nectar-loving insects.

The muntjac deer was introduced into the UK from China in the 20th century. It has gained a stronghold in southeast England, where it can cause damage to our woods through browsing.

Living up to its name, the bullhead has a characteristically large, flattened head and a tapering body. Look out for it in fast-flowing, stony rivers and streams.

The tiny, brown-and-white sand martin is a common summer visitor to the UK, nesting in colonies on rivers, lakes and flooded gravel pits. It returns to Africa in winter.

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.