Oarweed
The tops of Oarweed fronds can be spotted floating on low tides. Kelp beds are an important habitat, providing shelter for many other marine creatures.
Ocean quahog
This large burrowing bivalve is found on sandy seabeds around much of the UK. It is the longest-lived animal known to man, with one individual found to be 507 years old!
Olive squat lobster
These feisty crustaceans are the ‘Houdinis’ of the rocky shore, evading capture as soon as disturbed!
Opposite-leaved golden saxifrage
The flowers of Opposite-leaved golden saxifrage form 'trickles of gold' along riverbanks and streamsides in shady areas like wet woodlands.
Orange ladybird
The orange ladybird is pale orange with up to 16 cream spots on its wing cases. It feeds on mildew on trees like sycamore and ash, and hibernates in the leaf litter. It often turns up in moth traps.
Orange underwing
This birch-loving moth can be seen flying on sunny days in early spring.
Orange-clubbed sea slug
A small colourful sea slug that can be found grazing on sea mats on the rocky shore and beyond the low water mark.
Orange-tip
It’s easy to see where these butterflies get their name – the males have bright orange tips on their wings! See them from early spring through to summer in meadows, woodland and hedges.
Orca
Orca, sometimes known as ‘killer whales’, are unmistakable with their black and white markings. Although we do have a small group of orca who live in British waters, you would be lucky to see them!
Ordinary moss
Ordinary moss is very common in gardens and woodlands. moss provides shelter for many minibeasts, so encourage it to grow in your garden by providing logs, stone piles and untidy areas.
Osprey
A great way to get up close and personal with the magnificent osprey is via one of the many nestcams set-up in the places that it breeds: Scotland, Cumbria, Wales and the East Midlands.
Oxeye daisy
Often growing in swathes along a roadside or field margin, the oxeye daisy is just as at home in traditional hay meadows. The large, white, daisy-like flowers are easy to identify.