Mae'r rhywogaeth yma o siarc main a chain i'w gweld yn aml yn agos at y lan o amgylch ein harfordiroedd a gall dyfu i fod hyd at 6 troedfedd o hyd.

Horsehair worms are parasitic worms of the clade Nematoida alongside their sister taxa Nematoda, the roundworms. The most famous trait of certain species of horsehair worms is the ability to alter…

As its name suggests, the birch shieldbug can be found feeding on silver birch, and sometimes hazel, in mixed woodland. Adults hibernate over winter, emerging in spring to lay their eggs.

This large, brown beetle can be seen swarming around streetlights in spring. They live underground as larvae for years and emerge as adults often in large numbers. Listen for their characteristic…

Look out for the small holly blue in your garden or local park. It is the first blue butterfly to emerge in spring, and a second generation appears in summer. The caterpillars are fond of holly…

Looking like a short dandelion, but with a much rounder middle, colt's-foot is a 'weed' of waste ground and field edges that brightens up early spring with its sunshine-yellow…

So-named for the silvery-white appearance of its leaves, the white willow can be seen along riverbanks, around lakes and in wet woodlands. Like other willows, it produces catkins in spring.

The moon jelly is the most common jellyfish in UK seas, often washing up on our beaches. No need to worry though - it doesn't sting humans.

Pellitory-of-the-wall is a small to medium-sized herb that frequently grows from cracks in old stone walls, pavements, cliffs and banks, and churches and ruins.

The water stick insect looks just like a mantis. An underwater predator, it uses its front legs to catch its prey. Its tail acts as a kind of 'snorkel', so it can breathe in the water.…

The UK's smallest hawker, the hairy dragonfly is mostly black in colour, but has a distinctively hairy thorax. It can be found in grazing marshes and flooded gravel pits, and along canals…

Heralding spring, a carpet of sunshine-yellow lesser celandine flowers is a joy to see on a woodland walk. Look out for it along hedgerows, in parks and even in graveyards, too, from March onwards…