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Wildlife above and below our waves

Wales' coastline is home to colourful and amazing species

Tracey Dunford

Welcome to a magical marine world!

With around 2,750 kilometres (1,700 miles) of coastline around Wales, our seas provide the perfect home for marine wildlife such as seals, dolphins, porpoises, sharks and jellyfish.

The variety of landscapes in Wales is mirrored underwater from steep rocky reefs on the open coast to eelgrass beds found in shallow sheltered bays.

Above the shores, our cliffs and offshore islands are home to internationally important colonies of seabirds, including manx shearwaters, puffins and gannets.

2018 is Wales’ Year of the Sea and we are showcasing a different marine species every week during this special year.

We’ve also picked ten special places that we look after around the coastline of Wales for you to explore during the Year of the Sea. Each place has walking trails with information panels to help you make the most of your visit.

Compass jellyfish

Did you know that the compass jellyfish is a type of plankton?

Despite having no brain or heart and being 95% water, it propels itself along by rhythmically opening and closing its bell-shaped body.

It paralyses and catches its prey of fish, crustaceans and even other jellyfish with its 24 tentacles and four long, frilly mouth arms.

Its name comes from the radial compass pattern on top of the bell.

From July to October compass jellyfish are regularly found along the Welsh coast - both in the sea and washed up on beaches. If you see one, take care not to touch it or you might get a painful sting!

Harbour porpoise

Could you tell a harbour porpoise from a dolphin?

Porpoise are smaller than dolphins, at 1.5 metres long, and their dorsal fin is more triangular.

Unlike dolphins, porpoise are not acrobatic and do not jump out of the water. 

Harbour porpoise can be regularly seen along the Welsh coast. Particular hotspots include Skomer and Ramsay islands, Strumble Head and north east Anglesey, where they are often found feeding in areas of strong tidal currents.

Porpoise are an internationally protected species. In 2017 three marine Special Areas of Conservation were created around Wales to protect harbour porpoise.

Leatherback turtle

Leatherback turtles are the largest marine turtle in the world.

They nest on tropical beaches but in summer months they come to Welsh waters to feed on blooms of jellyfish.

The largest specimen ever was found stranded at Harlech in 1988. It weighed 916 kilograms and was almost three metres long.

Leatherback turtles have European protection and are listed in the Environment Act (Wales) 2016 as an important species for conserving biodiversity.

Keep a look out and get in touch if you see one. They are easy to identify with their black leathery skin, large size and prominent ridges on their back.

Thornback ray

The thornback ray is one of the commonest rays in Welsh waters.

As its name suggests, it has a line of thorns running along the middle of its back. It also has spines on its ‘wings’ – its elongated pectoral fins that help with swimming.

Its flattened body shape and brown-grey colouring is perfect for living on the seabed, where it is well camouflaged against sand and pebbles.

Like sharks, rays have a skeleton made from lightweight, flexible cartilage rather than bone.

Common sunstar 

The common sunstar is an aggressive and dominant predator.

Its many arms allow it to move fast - in starfish terms - covering over five metres in half a day to chase down its prey of sea urchins, brittle stars and common starfish.

It is not a fussy eater and will also graze on anemones, sea squirts and bivalves (such as oysters, mussels and scallops).

Like other starfish it can regenerate its arms if they are injured or even missing, so long as its central disc is still intact.

Although it can be found all around the British coast, it is more common in the north and only occasionally found in Welsh waters.

Honeycomb reef worm


Who builds the biggest, fastest reefs?

Not coral. It’s the Honeycomb reef worm.

This tube dwelling worm builds itself a home from sand or fragments of shell to protect it from predators.

The worm never leaves its home but, when the tide covers the reef, it crawls to the edge to filter plankton from the water.

The biggest reefs in Wales are in Cardigan Bay, where patches can stretch to over five kilometres along the shore.

It is a priority species in Wales, at risk where coastal defences are constructed which reduce the mobile sand that the worms build their reefs from. 

If you see a reef, please take care not to walk on it – it is fragile and easily broken.

Ross coral 

Why is this Ross coral’s name misleading?

Because it isn’t a coral at all.

It is a colony of countless individuals living together in microscopic, chalky building blocks. It belongs to the bryozoan group of animals.

These fragile structures can grow up to an impressive one metre across, but they are delicate and vulnerable to damage from marine activity such as fishing and anchoring.

At the Skomer Marine Conservation Zone we photograph many of these colonies to study how their population changes over time and to record any impacts on them.

Small spotted catshark

Is this a dogfish or a catshark?

Both! It is often called a ‘dogfish’ but it is actually a small spotted catshark.

Catsharks may be small in size, but they are the largest family of sharks with over 160 species worldwide.

Catsharks are common in Welsh waters and are often seen by divers and anglers.

Catshark eggs need to be kept safe for eight months while the baby sharks develop inside. The egg cases (known as mermaid's purses) are really tough, and have long tendrils that tangle in seaweed to keep the eggs hidden.

Keep a look out for empty mermaid's purses washed up on the shore.


Gannets are the largest breeding seabird in the UK.

They have special adaptations that allow them to absorb the shock of plunging into the sea at 60 mph from 100 feet in the air to catch their food.

They close off their nostrils, have a shatter-proof membrane that protects their eyes, and have extra cushioning in their neck and shoulders.

The island of Grassholm off Pembrokeshire is the second largest single rock ‘gannetry’ in the Atlantic with over 100,000 birds.

Sadly, plastic pollution is affecting gannets. While building their nests from natural floating debris they also pick up plastic fishing line, synthetic rope and other plastics, which causes many to get tangled and some to die snagged to their nests.

Yellow staghorn sponge

Yellow staghorn sponge

Have you ever mistaken a sponge for a plant?

It attaches to a rock, just like a plant. 

It has no heart, brain, muscles or mouth.

But it is an animal, and it is very successful.

This yellow staghorn sponge is one of 10,000 species of sponge throughout the world.

You might wonder how it eats without a mouth.

It extracts food from the water that circulates through the many holes and channels in its body.

Spiny starfish 

 Spiny starfish

Spiny starfish can be giants.

Usually 20-30 cm across, they can grow up to an impressive 75 cm, making them the largest starfish in UK waters.

They are found up to depths of about 200 metres but, if you are lucky, you may find one at low water.

Spiny starfish do not have eyes. Instead, they have light sensitive organs at the tips of their arms which allows them to detect movement.

They are voracious predators, eating molluscs, crustaceans, fish and even other starfish.

And they are not bothered whether their dinner is dead or alive!

Sea slug

Sea slug

Do you know what sea slugs like to eat?

Unlike land slugs, sea slugs are very picky eaters as each species has its own specific prey.

Sea slugs can be ferocious too! The elegant sea slug feeds on sea squirts by burrowing inside and eating them from the inside out. 

Those that eat stinging animals can store the stinging cells in their own bodies and use them to protect themselves.

And, unlike land slugs, many are very colourful.

Their scientific name is nudibranch, meaning ‘naked gill’, referring to their external respiratory organs. 

Jewel anemone

Jewel anemone

Jewel anemones can reproduce in an interesting way.

They can divide themselves into two, leading to densely packed areas of tiny anemones forming on the rocks.

They are amazingly colourful animals too.

They can be pink, purple, green, orange or brown, and they have a small ball on the end of their tentacles giving the impression of a glistening jewel.

Cuckoo wrasse

Cuckoo wrasse

Cuckoo wrasse are one of our most colourful fish.

They have striking orange and blue markings that wouldn’t look out of place in tropical waters.

But they have another remarkable feature too.

Cuckoo wrasse are one of the few fish that can change their gender (they are ‘protogynous hermaphrodites’).

They are all born female, but can become male if the dominant male disappears. 



Crawfish are also known as crayfish and spiny lobsters. 

The name ‘spiny lobster’ comes from the sharp spines that cover their heavy, orange-brown shells. 

They have two long antennae, used for fighting and defence, and two smaller antennules, which are sensory organs that detect chemicals and movement in the water.

Crawfish were common on our rocky reefs but since the 1980's have become scarce.

They are listed a species of principal importance in the Environment (Wales) Act 2016, but still do not have any legal protection other than minimum landing size.

Always ask where the fish on your restaurant menu has come from and whether it is from a sustainable source.

Find out more about Crawfish

Common limpet

Common limpet

Don’t be underwhelmed by the common limpet, found all along our rocky shores.

Did you know it has a clever way of protecting itself from the elements?

A limpet always comes back to the same spot after feeding – this is called the ‘home scar.’

Its pyramid-shaped shell matches the contour of the ‘home scar’ rock perfectly, allowing it to clamp down with its muscular foot and make a tight seal against the battering waves and drying air.

When the tide goes out, the limpet moves about to feed, scraping films of seaweed off rock surfaces with its ‘radula’ – a ribbon like tongue with rows of teeth. 

Then it goes home to survive another battering!

Star sea squirt

Star sea squirt

Ever wondered how the star sea squirt got its name?

Each star sea squirt is actually a colony of many small, colourful individuals called zooids, which come together to form circular, oval or star-shaped clusters within a clear, fleshy matrix.

These clusters can look like colourful stars growing on rocks and seaweeds.

But what about the ‘squirt’?

The water that each zooid pumps through its body while filtering out food particles is discharged into a common space within the matrix, where it leaves - or is squirted - out of the colony.

Bottlenose dolphin

Bottlenose dolphin

Talking helps bottlenose dolphins catch their prey.

They hunt in small groups, calling to each other to coordinate their movements.

They feed on locally abundant fish and can eat around 5% of their body weight daily.

The shape of their teeth is especially good at holding slippery fish, with interlocking rows of conical pegs.

You can often spot pods of dolphins from the Welsh coast, especially in Cardigan Bay Special Area of Conservation.

Grey seal

Grey seal

Grey seals are Britain’s largest predator.

The bulls (males) can weigh 230 kg - half the weight of a grand piano! - consuming 5 kg of fish a day.

Although they usually feed in shallow waters they can go down to an incredible 70 metres, being able to stay underwater for six minutes at a time.

You can spot grey seals along the Welsh coast all year, but especially in the autumn when they come ashore to give birth to their pups on the remote beaches around the Skomer Marine Conservation Zone.

Forest kelp

Forest kelp

Did you know we have underwater forests in Wales?

Dense forests of large brown kelp plants grow all around our shallow coastline.

Below the forest canopy, a wealth of life thrives, with over 250 species recorded living there.

Anchored firmly to the rocks, the kelp forests create a network of nooks and crannies ideal for fish, crabs, starfish and urchins to make their home in.

The ‘tree trunks’ (called stipes) are colonised by sponges, sea firs and sea mats.

Pink sea fan

Pink sea fan

Does coral grow in Wales? Yes, it does!

Pink sea fans are a branching soft coral that can be found in the Skomer Marine Conservation Zone (MCZ).

This is their northern most stronghold - they can also be found in Africa and the Mediterranean.

Pink sea fans (also known as octocorals) have a tree-like structure that is attached firmly to a rock with a holdfast.

Their branches are covered in tiny anemone-like polyps which catch food in the water.

They grow very slowly this far north, and many in the Skomer MCZ are 50-100 years old.

Sea urchin

 Sea Urchin

Why are sea urchins like rabbits? They are both grazers.

Sea urchins are known as the rabbits of the marine world because they are the most important grazers of underwater rock surfaces.

Sea urchins are vital to maintaining biodiversity.

By efficiently vacuuming rock surfaces bare while feeding on seaweed and encrusting animals, they make space for larvae of different species to settle on the rock and, as a result, encourage species diversity.

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