Wildlife of Britain & Beyond

Semibalanus balanoides

The most familiar barnacle on British rocky shores, carpeting exposed surfaces in the upper intertidal zone. A barnacle is a crustacean that lives cemented to a rock and extends feathery legs (cirri) to sweep plankton from the water.

Actinia equina

The most abundant sea anemone in Britain, the beadlet is familiar in rock pools as a smooth, dark-red blob when the tide is out. When submerged it extends up to 192 tentacles to catch passing prey, including small fish and crustaceans.

Ophiothrix fragilis

Brittlestars form dense beds — sometimes millions per hectare — on coarse seabeds across the UK continental shelf. Unlike starfish, they move by lashing their slender arms rather than using tube feet. Arms break off easily to confuse predators.

Lithobius forficatus

The most familiar UK centipede, a fast-moving predator with 15 pairs of legs and powerful venom claws. Found under stones and bark throughout the UK, it hunts earthworms, slugs and insects, and is in turn eaten by shrews and hedgehogs.

Cerastoderma edule

Found in enormous numbers on sandy estuaries and sheltered bays around the UK. Cockles are harvested commercially by hand-raking and mechanically, and are ecologically critical as food for wading birds and flatfish.

Sepia officinalis

A highly intelligent mollusc with excellent eyesight and the ability to change colour instantly for camouflage. Cuttlefish visit UK inshore waters in spring to breed and lay black eggs among kelp. Their internal shell washes up as cuttlebone.

Lumbricus terrestris

The most important invertebrate in British soil, dragging organic matter underground and aerating the soil with its tunnels. Charles Darwin described it as one of the most important animals in the world. A key food source for blackbirds and robins.

Pagurus bernhardus

One of Britain's most familiar shore creatures, the hermit crab protects its soft abdomen by inhabiting the empty shells of whelks and other molluscs. It upgrades to a new shell as it grows, sometimes fighting for the best ones.

Aurelia aurita

The most familiar jellyfish in UK waters, the moon jellyfish washes up on beaches in summer. It has four distinctive pink rings (the gonads) visible through its translucent bell and feeds on plankton using short, frilly tentacles.

Patella vulgata

One of Britain's most familiar shore creatures, clinging to rocks with a grip strong enough to withstand waves in a severe storm. Each limpet grazes a territory of algae and returns to exactly the same spot when the tide comes in.

Homarus gammarus

Britain's most valuable commercial shellfish species, found on rocky reefs around the entire coast. Blue-black when alive, it turns red when cooked. Lobsters are long-lived and slow-growing, making them vulnerable to overfishing.

Mytilus edulis

One of Britain's most important filter-feeding bivalves, forming dense beds on exposed rocky shores and estuaries. Mussel beds provide habitat for dozens of other species and are farmed commercially around the UK coast.

Octopus vulgaris

The most intelligent invertebrate, capable of learning, problem-solving and changing colour and texture instantly. Occasionally encountered by UK divers in the south-west, it has become more frequent in recent years as seas warm.

Littorina littorea

The most abundant mollusc on British rocky shores, found from the splash zone to the low water mark. Periwinkles are the dominant grazer of rocky shores, keeping surfaces clear of algae. They have been eaten as seafood for centuries.

Palaemon serratus

The common prawn is found in rock pools and shallow coastal waters around the UK, its transparent body with brownish banding making it surprisingly well camouflaged. It scavenges detritus and hunts small invertebrates.

Carcinus maenas

The most familiar crab in Britain, found on rocky shores and in estuaries around the entire coastline. A ferocious predator and scavenger, it has spread globally as one of the world's most invasive marine species.

Loligo vulgaris

A shoaling, fast-moving predator important in UK marine food webs. Squid are fished commercially and targeted by recreational anglers with lures at night. They spawn in winter, laying clusters of finger-like egg cases on the seabed.

Asterias rubens

The most familiar echinoderm on UK shores, the common starfish is an important predator of mussels and oysters. It can regenerate lost arms and even grow a new body from a single arm. Colours range from purple to orange to brown.

Oniscus asellus

The most common woodlouse in Britain, found under bark, stones and in leaf litter. Not an insect but a crustacean, it breathes through gills and must remain moist. It plays a vital role in decomposition and nutrient recycling.

Asterina gibbosa

A small, five-sided starfish found under rocks in south-west Britain. Despite its diminutive size of just 5 cm, it is capable of eating molluscs and worms. It is a sequential hermaphrodite, beginning life as male and becoming female.

Nucella lapillus

A predatory mollusc that drills through the shells of barnacles and mussels to feed on the soft tissue inside. Dog whelks suffered severe population declines due to tributyltin (TBT) anti-fouling paint on boats but have largely recovered.

Cancer pagurus

One of Britain's most commercially important shellfish, recognised by its characteristic pie-crust shell edge and black-tipped claws. It is fished around the entire UK coast, with the largest catches from Devon, Cornwall and Scotland.

Echinus esculentus

Britain's largest sea urchin, with a beautiful pink-purple spiny test and white-tipped spines. It grazes on encrusting algae on rocky reefs. The roe (gonads) is a gourmet delicacy known as uni and is harvested commercially in Scotland.

Polydesmus angustus

A common millipede of woodland leaf litter across the UK. Unlike centipedes, millipedes are herbivores or detritivores, feeding on dead plant material. This species has flattened body segments and two pairs of legs per segment.

Margaritifera margaritifera

One of the longest-lived invertebrates in the world (up to 130 years) and one of the rarest. UK populations have declined by over 90%. It requires clean, fast-flowing rivers with salmon and trout as juvenile host fish.

Cornu aspersum

The most familiar land snail in Britain, beloved by gardeners for its shell but less welcome for its appetite for young plants. Snails are an important food source for song thrushes, which smash shells on stone anvils.

Araneus diadematus

The most familiar UK spider, building a perfect orb web each morning, often destroyed and rebuilt overnight. Recognised by the distinctive white cross on the abdomen. Females eat the smaller males after mating in autumn.

Lepas anatifera

Goose barnacles attach to floating objects — logs, buoys, sea beans — and are regularly washed ashore on UK Atlantic-facing beaches after westerly gales. Medieval naturalists believed geese hatched from them, giving both their names.

Limax maximus

Britain's largest slug at up to 20 cm, with a keel at the tail. It is largely carnivorous, feeding on other slugs and fungi rather than living plants. It mates acrobatically, intertwining while suspended from a mucus thread.

Lymnaea stagnalis

Britain's largest freshwater snail, reaching 6 cm, found in ponds, lakes and slow rivers with abundant aquatic vegetation. It is an important indicator of water quality and a prey species for diving beetles and water birds.

Pecten maximus

Britain's largest bivalve, with a fan-shaped shell reaching 15 cm. Scallops can swim by clapping their shells to escape predators. They are among the UK's most valuable shellfish, fished by dredge and hand-diving around Scotland.

Hydrophilus piceus

Britain's largest aquatic insect at 5 cm, the great silver water beetle is a rare inhabitant of fen ditches and ponds in south-east England. Adults and larvae are predators of aquatic invertebrates, tadpoles and small fish.

Echinocardium cordatum

The heart urchin or sea potato lives buried in sand below the tide line, feeding on organic particles. Its pale, heart-shaped empty test is commonly found on UK beaches and is instantly recognisable with its furry surface texture.

Alitta virens

Britain's largest marine worm, reaching 90 cm. It burrows in estuarine mud and sand and emerges to swim for reproduction in mass spawning events called swarming. A key prey item for wading birds and fished extensively for bait.

Cyanea capillata

The world's largest jellyfish, with a bell exceeding 2 metres and trailing tentacles up to 37 metres. It appears in UK waters in late summer and autumn and can deliver a powerful sting. Photographed memorably around Scotland and Ireland.

Arenicola marina

The lugworm lives beneath intertidal sand and is revealed by its characteristic coiled sand casts at the surface. It is the most important food source for wading birds on UK estuaries and is widely used as fishing bait.

Ostrea edulis

Once filtered vast quantities of water in British estuaries, the native oyster has declined by over 95% due to overfishing, disease and habitat loss. Extensive reef restoration projects are underway around UK estuaries.

Armadillidium vulgare

The pill bug or pill woodlouse can roll into a perfect sphere when threatened, a defence unique among UK woodlice. It prefers drier conditions than other species and is most common on calcareous soils in southern Britain.

Dolomedes fimbriatus

Britain's second largest spider, the raft spider walks on water using surface tension, dipping its legs in to detect vibrations from insect prey below. It is restricted to acidic bogs and lowland heathland in southern Britain.

Planorbarius corneus

A large freshwater snail with a distinctive flat, coiled shell like a ram's horn. It grazes algae in ponds and slow rivers and uses haemoglobin (like vertebrates) to carry oxygen, allowing it to survive in low-oxygen water.

Ensis magnus

The razor clam burrows rapidly into intertidal sand using a powerful muscular foot. It can dive to 60 cm in seconds to escape predators. UK waters support important stocks and razor clams are harvested commercially in Scotland and Ireland.

Helix pomatia

Britain's largest land snail, introduced by the Romans and now established on chalk downland in southern England. It is fully protected under the Wildlife and Countryside Act and is an increasingly rare sight on warm, calcareous grassland.

Pacifastacus leniusculus

Introduced from North America for aquaculture, the signal crayfish has spread throughout most of England's river system. It carries crayfish plague, burrows destructively in riverbanks and is a serious invasive species.

Anemonia viridis

A beautiful anemone of clear, sunlit pools in south and west Britain, with long flowing tentacles that are often vivid green or grey with purple tips. It harbours photosynthetic algae in its tentacles and cannot fully retract them.

Maja brachydactyla

Britain's largest native crab, with a spiny carapace and long, spindly legs. Spider crabs aggregate in spectacular mass aggregations in summer before moulting, forming piles in shallow bays that can number thousands of individuals.

Marthasterias glacialis

Britain's largest starfish, reaching 70 cm across and bearing prominent spines on its five arms. Found on rocky reefs in the south-west and Scotland, it is a major predator of scallops, mussels and other shellfish.

Argiope bruennichi

A spectacular spider that has recently colonised south-east England and is spreading northwards. The female's yellow and black banding mimics a wasp. She builds a large orb web in low grassland with a distinctive zigzag silk band (stabilimentum).

Argyroneta aquatica

The world's only truly aquatic spider, constructing a silken diving bell filled with air bubbles in which it lives and breeds. Found in ponds and slow rivers, it is a fierce predator of aquatic invertebrates and small fish.

Austropotamobius pallipes

Britain's only native crayfish, now endangered following the arrival of the American signal crayfish which carries crayfish plague fatal to it. Surviving populations are found in limestone streams and rivers in England and Wales.

Cepaea hortensis

A familiar hedgerow and grassland snail with highly variable shell banding. The extraordinary variety of colour and banding patterns — from plain yellow to dark-banded brown — has made it a classic subject for population genetics research.