A seal on the beach with more seals in the background
British wildlife

Things you might spot along the coasts of the British Isles

By Katie Spence

The coasts and beaches of the British Isles are full of incredible wildlife. From tiny lugworms buried deep in the sand to huge sunfishes basking in the waves, there’s an abundance of nature to be discovered.

Here are 10 things that you might spot around the coasts of the British Isles.

Basking sharks

A basking shark with its mouth open

The basking shark is the largest fish in the British Isles. Reaching lengths of up to 10 metres, it’s the second largest fish in the world. It belongs to the order Lamniformes – a group of sharks commonly known as mackerel sharks that also includes the great white shark.

Basking sharks have enormous mouths that can stretch over a metre wide. They’re filter feeders, so they don’t use teeth to catch prey, instead they use gill rakers. As they swim slowly through the water with their mouths wide open, they use these specialised, comb-like structures to trap zooplankton from the seawater. This highly efficient feeding method allows them to consume vast amounts of this microscopic prey.

As seasonal visitors to our waters, we typically only see basking sharks between May and October. They’re most commonly spotted off the coasts of Cornwall and Devon, as well as around the Isle of Man and the Scottish Hebrides. The best time to see one is on a sunny day when zooplankton will be abundant near the surface of the water.

Lugworms

The cast of a lugworm on the sand

If you’re walking along a sandy beach, you may spot worm-shaped mounds. What you’re seeing on the surface is the cast, or poo, of a lugworm who lives buried deep in the sand.

Lugworms spend most of their time in u-shaped burrows that are under the sea until the tide goes out. They feed on microorganisms in the water, excreting any matter they can’t digest into mounds on the surface of the sand.

There are two species of lugworm, each produces different casts on the sand. The blow lugworm is about 20 centimetres in length and burrows between 20–40 centimetres below the surface. You can usually spot the entrance to its burrow, which looks like a little hole, close to the cast.

The other type of lugworm is the black lugworm. They’re usually longer at about 40 centimetres and burrow deeper into the ground to around 70 centimetres. Their casts are normally spiral shaped, unlike the blow lugworms who leave a messier looking cast.

Puffins

A puffin with sand eels in its mouth

The puffins we’re familiar with in the British Isles are Atlantic puffins. They belong to the Fratercula genus, along with the tufted puffin and the horned puffin.

In the winter, puffins spend most of their time at sea and will shed their brightly coloured bills for duller ones. In the spring months, the birds make their way to land, either to cliffs, islands or shores, to breed. It’s during this time that you might see one. Sometimes you might catch sign of them billing – hitting their beaks together, which strengthens their bond.

Puffins are burrow-nesting seabirds. They create nests in rocks and soil ready for the arrival of their young, which are called pufflings. After a puffling hatches, it will stay burrowed in the nest for around six weeks. It will then head to sea at night to avoid predators.

Adult puffins are extremely good hunters and will carry prey back to the nest for their pufflings. Their tongues are fleshy with a rough end, and they have spines lining the tops of their months. This enables them to hold onto large amounts of slippery prey while they hunt. In the British Isles, they mainly eat sand eels.

If you see puffins, remember to keep your distance and to not disturb them.

Ocean sunfishes

Ocean sunfish on the surface of the water

During the warmer summer months, particularly off the coast of Cornwall, you might be lucky enough to catch sight of one of the ocean’s more unusual looking creatures – the ocean sunfish. It’s the second largest bony fish in the world, reaching lengths of up to three metres and weighing around 1,000 kilogrammes.

Ocean sunfishes have a very distinctive appearance. Their bodies are laterally flattened, giving them a disc-like or oval shape. Instead of a tail fin, they have a clavus – a stiff, rudder-like structure. They also have a tall, triangular dorsal fin that can often be seen on the surface of the water. It’s because of this that sunfishes are sometimes mistaken for sharks, especially when seen from a distance.

Despite their size, they’re not particularly strong swimmers. Their movements through the water tend to be slow and they’ll often drift along with the currents. You’re most likely to see one basking on the surface of the ocean as it looks for its next meal – primarily jellyfish.

Adders

An adder near some grass

Adders are a type of viper and the only venomous snake native to the British Isles. They’re distributed across much of the isles, inhabiting a wide range of environments, including woodland, heathlands, moorlands, sand dunes and occasionally beaches.

Varying in colour, males are typically grey or silver whereas females are reddish-brown or coppery. They all have a dark zigzag pattern running down the top of their bodies along with a characteristic v- or x-shaped marking on the top of their heads. These markings help camouflage them, making them difficult to spot unless you’re looking closely.

While not aggressive, adders may bite if they’re accidentally stepped on or handled. Bites to people are extremely rare and usually occur when the snake feels threatened. Adders use their venom to immobilise and kill small prey, including rodents, lizards, frogs and ground-nesting birds.

Lion’s mane jellyfish

Lion's mane jellyfish near the surface of the water

The lion’s mane jellyfish is one of the largest species of jellyfish. It has a bell-shaped body that can reach up to half a metre across. From this hangs clusters of long, thread-like tentacles that can extend up to three metres. These tentacles are lined with thousands of stinging cells, called nematocysts, which it uses to capture and paralyse its prey. If you see a lion’s mane jellyfish, even a dead one washed up on the beach, it’s important not to touch it, as their sting will still be very painful.

Lion’s mane jellyfish prefer cooler waters and have been spotted off the coasts of Scotland, northern England, Wales and Ireland, though they can occasionally be seen further south. Sightings tend to increase during the summer months when plankton levels rise.

Natterjack toads

A natterjack toad close up

Natterjack toads are extremely rare in the British Isles but can occasionally be found in coastal sand dunes. They need shallow, warmer water to breed successfully, so can sometimes be found near, or in, water that’s formed between sand dunes, which is called slacks.

The natterjack can be recognised by a distinct yellow line that runs along the length of its back. It has shorter legs than the more common European toad. Instead of hopping, the natterjack mainly gets about by walking and running.

One of the most striking features of the natterjack toad is its extraordinarily loud mating call. During the breeding season, males make a sound that can be heard up to 1.5 kilometres away.

There are a number of ways which you can help toad species in the British Isles.

Seahorses

Close up of a seahorse

There are two species of seahorse in the British Isles – the short-snouted seahorse and the spiny seahorse. Both species are mostly found along the south and west coasts of England and Wales but have been spotted as far north as the Shetland Islands. 

You’re most likely to see one in a bed of seagrass. James Maclaine, our Senior Curator of Fish, explains “if you ever see a seahorse in an aquarium, it’ll probably be using its long prehensile tail to wrap itself around a bit of weed or grass. They’re normally found in places with lots of vegetation without strong currents. They’ve got tiny fins so they like calm water with lots of things that they can grab on to.”

Both species are well camouflaged and can change colour to blend seamlessly into their surroundings, helping them to avoid predators. Unlike many fish, seahorses don’t have teeth. Instead, they feed by sucking up tiny planktonic prey such as small shrimp and other microscopic organisms.

Leatherback turtles

Close up of a leatherback turtle swimming

The leatherback turtle is the largest species of turtle in the world. It can reach lengths of more than 2.5 metres and weigh more than a tonne.

It gets its name from its unique shell, which is formed of thick, leathery skin, unlike the hard, bony shells of other marine turtles. Leatherbacks are among the deepest diving animals. They’ve been recorded diving to depths of around 1,280 metres and can remain submerged for up to 85 minutes at a time.

Leatherbacks are solitary travellers and are found in oceans across the globe. Unlike most reptiles, leatherbacks can regulate their body temperature to remain warmer than the surrounding water. This adaptation enables them to hunt in colder waters.

While sightings of leatherback turtles in the waters of the British Isles are rare, they do occasionally appear, most commonly off the west coasts of England, Wales and Scotland during the summer months. These visits are usually linked to seasonal increases in jellyfish populations, which draw the turtles into our waters to feed.

Seals

Close up of a seal with its head out of the water

There are two species of seal that you’re likely to see off the coasts of the British Isles – grey seals and common seals. Despite their name, common seals are in fact less common than grey seals. They’re also generally smaller than grey seals and have v-shaped nostrils and shorter, concave-shaped heads. Their fur colour varies from light to dark brown. When resting on land, common seals sometimes adopt the banana position with their head and tail raised.

The grey seal can be recognised by its distinctive long nose – its scientific name Halichoerus grypus means hook-nosed sea pig. Unlike the common seal, the nostrils of the grey seal are parallel. Grey seals spend much of their time at sea hunting for fish, squid and octopus. They have highly sensitive whiskers, which they use to detect their prey.

Both types of seal can be seen throughout the British Isles and are commonly spotted along the coastline and on islands. It’s also not unusual to spot seals lounging on beaches or even swimming in inland rivers and bodies of water. They come ashore to rest, digest food and give birth. It’s important to avoid disturbing them and to keep dogs on leads if you’re near them, as they’re easily startled and can be aggressive if you get too close.

Find out about the plants and animals that make the UK home.

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