Thanks to our partnership with the incredible Marine Conservation Society (MCS), we’ve been able to metaphorically dive into new waters to capture data from Marine Protected Areas throughout the UK’s vast ocean offerings. Marine Protected Areas are our national parks of the sea; they provide a safe haven for entire underwater ecosystems which often house rare and threatened aquatic animals and plants. Designating these zones means that they can stay protected.
Currently, there are 371 Marine Protected Areas that comprise 38% of the UK’s seas. Fortunately, a major ambition of the MCS is to have 30% of the UK’s oceans highly or fully protected by 2030 – a target that could be easily achieved if these zones are safeguarded. 
Created by the then Head of Conservation at the MCS, Seasearch is a project aimed at recreational divers and snorkellers who want to learn about marine life whilst simultaneously working to protect and restore the ocean. Crystalising the notion that any dive can be a Seasearch dive, the project, which is led by the MCS, encourages divers to collect data from Marine Protected Areas and other sites around the UK to help track the health of marine environments. In this article, we spotlight five important habitat types, where you can find them, and what species you might find there (if you look really hard!).
You too can turn the tide on species depletion and underwater nature loss by volunteering in the Seasearch programme.
Volunteer with Seasearch
Dive into:
Seagrass habitat
Commonly known as the only flowering plant in the ocean, seagrass is predominantly found in shallow, calm waters where it can soak up the sun’s rays (usually at depths of 0–5 metres). When there is enough of it, it becomes a meadow which provides habitation and food for all manner of wonderful sea life – the number of species that have been recorded by Seasearch currently stands at 631.
Much like grass on land, its roots can spread out beneath the seabed and shoot up in areas where it may be a little sparse. Not only is this a great way to reproduce, but it also helps prevent coastal erosion by stabilising the sediment in the seabed. Another great benefit of seagrass is that it can sequester carbon whilst producing oxygen – a win-win.
Seagrass meadows often act as fish nurseries and in the UK, they sometimes host rare seahorses and jellyfish. The most studied beds by Seasearch are located along the south coast of England, in the counties of Cornwall, Devon and Dorset, as well as two further sites in Northern Ireland and Scotland. One such seagrass bed recently found in Cornwall proved to be one of the largest ever to be found in the UK.
Image credit: MCS and Peter Bardsley
Species highlights
Stalked jellyfish (Stauromedusae) – looking perhaps more like a squid than your traditional jellyfish, this Cnidaria has a unique trumpet shape with eight tentacle-like arms with suckers on the end. Its stalk also has a sucker which it uses to stick to rocks and marine plants in rock pools and shallow waters. Despite being so seemingly observable, they are often not detected due to their diminutive size (up to 3cm) and the fact that they camouflage well on their plant of choice. Report a sighting of this nationally scarce jellyfish here.
Long-snouted seahorse – this rare seahorse is a UK priority species and is protected under the Wildlife and Countryside Act 1981. Also known as the spiny seahorse, this critter can be found clinging to seagrass or algae with its prehensile tail, as they are known to be poor swimmers. As the name suggests, they have longer snouts than their cousins and are most commonly greenish-yellow in colour.
Common cuttlefish – despite its name, this cephalopod is not actually a fish but rather belongs to the same family as octopus and squid. It is also not that common, only occasionally being spotted by Seasearch’s volunteers. This could perhaps be due to its advanced colour-changing and camouflaging abilities, despite being colour-blind. They also have one of the largest brain-to-body ratios and have the ability to count.
- Japanese wireweed – originated in Japan; first recorded in Britain in Portsmouth in 1971
- Green sea fingers – originated in the Pacific Northwest; first recorded in Britain in Yealm Estuary, Devon in 1939
Maerl bed habitat
Perhaps not as commonly celebrated as seagrass, but easily as recognisable, Maerl beds are formed by unattached nodules of calcareous red algae that create spiky underwater carpets of purply-pink hard, chalky seaweed. Think stepping on Lego in the middle of the night, times 1,000!
Maerl, a type of coralline algae (which means that it resembles coral) has a hard brittle skeleton. Starting in the shallows and reaching depths of up to 20 metres, maerl beds in the UK are often found in Scottish waters at locations such as Wester Ross, Loch Sween and South Arran. It’s here that the majority of the 954 identified species have been recorded, but there are also Special Areas of Conservation in Northern Ireland and Cornwall (the latter being genetically distinct from maerl found at any other site), as well as a Marine Conservation Zone on the Isle of Wight.
Though rare in the UK, these vibrant blankets of calcium can be incredibly biodiverse and live for thousands of years. Their mesh-like framework is the perfect refuge for animals such as the harbour crab, the small-spotted catshark and the spiny sea star, but the structures are easily damaged by trawling and dredging, and can take decades or centuries to recover.
Image credit: MCS and Billy Arthur
Species highlights
Black brittle star – this brittle star is a species that can be found around most of the UK, sometimes in the intertidal zone. They can be found in large numbers (the summer is the best time for spotting) and can form colonies with the common brittle star. With a small central body and five thin, flexible arms, these echinoderms create dark-coloured blankets that shroud the maerl, giving it an otherworldly feel.
Gravel sea cucumber – this species of sea cucumber is so-called as it spends a lot of its time in the substratum with only its tentacles visible. When it needs to move, it can ‘walk’ along the seabed or maerl using its tube feet which are equipped with suckers. They can be found all year, although they have been known to hibernate in the winter.
Eyelash fanworm – some animals are just easy to name; this one would have been a cinch. Fanning out to look scarily similar to an eye with eyelashes, this beautiful worm can grow up to 20cm long and will be most easily found from May to September.
- Japanese wireweed – originated in Japan; first recorded in Britain in Portsmouth in 1971
- Slipper limpet – originated on the east coast of North America; first recorded in Britain in Essex in the late 1880s (sadly, they occur in large densities and produce lots of 'poo' which fills in all the spaces between the maerl and smothers it, preventing light getting to the algae)
- Leathery sea squirt – originated in the Pacific Northwest; first recorded in Britain in Plymouth in 1953
Chalk reef habitat
We are so lucky here in the UK to have the longest chalk reef in Europe, possibly the world. The Cromer Shoal Chalk Beds, the only protected chalk bed location in the UK (there are other chalk reefs in Yorkshire and Kent), are over 20 miles long and have been dubbed Britain’s Great Barrier Reef.
Occupying a depth of up to 8 metres, this reef has been here for 100 million years. Over this almost unfathomable amount of time, the soft rock has understandably eroded into dramatic towering arches, caves and gullies, a lot of which were made during the Ice Age. These underwater caverns and valleys support a kaleidoscope of marine flora and fauna including numerous species of anemones, sponges, crabs and lobsters. To date, 622 species have been recorded.
In 2016, the importance of the reef was highlighted by its designation as a Marine Conservation Zone. Being an inshore site, a mere 200 metres off the North Norfolk coast, it’s vital that the local community successfully collaborates with non-governmental organisations to ascertain the best solutions for protecting this ancient wonder. Bottom-towed fishing is prohibited but over-fishing of crab (as in the famous Cromer crab) and lobster is still possible.
Image credit: MCS and Dawn Watson
Species highlights
The Parpal Dumplin – discovered in 2011 and not known to exist anywhere else in the world, this cute little sponge was the subject of a competition to name the new discovery. A 9-year-old schoolgirl gave it its name because ‘the sponge is purple and it looks like a dumpling’. Simple. The spelling and the way it is said connects it to its home in Norfolk.
Painted topshell – this stunning mollusc has one of the most beautiful shells you’re likely to find. The shell is conical in shape and has whorls of colour starting at its flat base, travelling in a spiral all the way to its zenith. Pinks, purples, oranges and yellows are all found on the home of this lucky snail.
Tom-pot blenny – a favourite among divers and snorkellers, this clown-like fish is often found smiling and will come out of its hole in the reef to study divers. They are known as ‘the fish with antlers’ thanks to the frilly tentacles poking out of the top of their head.
- Devil’s tongue weed – originated in Eastern Asia; first recorded in Britain in the Solent Estuary in 1969
- Pileolaria tubeworm – originated in the Pacific Northwest
Soft mud habitat
The very fine particles that constitute the soft, burrowed muds that make up this habitat can only settle where there is little movement from tidal currents or a lack of disturbance from waves. This typically happens offshore in waters deeper than 50 metres. Luckily for Seasearch, the sheltered conditions of Scotland’s sea lochs, where depths rarely pass 30 metres, means that deep-sea habitats can be found close to shore.
These shallower waters around the Scottish coast imitate the conditions found at greater depths out to sea and therefore provide us with the chance to see an ecosystem that would otherwise be out of reach to recreational divers. Scotland’s west coast is a muddy treasure trove of delights, with Marine Protected Areas found at lochs Duich, Sunart, Sween, Fyne and Goil. These zones house a rainbow of colourful species that brighten up the dull mud, including the phosphorescent sea pen, the sealoch anemone and the serpent’s table brittlestar – just three of 877 recorded species.
Unfortunately, there are dangers facing this habitat. There is still an issue with recreational fishers digging out bait from the mud and towing fishing gear along the mud bed. These disturbances can upset the equilibrium of this underrated habitat and threaten not only the species found here but also the wider environment; did you know that deep water sands and muds are one of the biggest stores of carbon in the UK environment?
Image credit: MCS and Dan Bolt
Species highlights
Fireworks anemone – the UK’s biggest anemone is also one of its most fabulous. With tentacles that can reach 30cm, this UK priority species emits blue and green light under UV conditions, showcasing wonderful fluorescent patterns (see image above).
Dublin Bay prawn – also known as the Norway lobster, langoustine or scampi, this crustacean has the typical body shape of a lobster and is found the world over (one of the more populous of our rare species!). They are nocturnal and create their burrows by digging into the soft mud.
Organpipe tubeworm – although they occur across the north-east Atlantic and Mediterranean, they rarely congregate together as reefs. These tubeworms have feathery tentacles and can come in a variety of reds, pinks and oranges. The worms are well-suited to the soft mud habitat as they are sensitive to light and vibrations and can quickly retract their tentacles and plug their tubes at the slightest sign of disturbance.
No non-native species have been recorded as of yet.
Kelp forest habitat
The last habitat on our list may sound like it’s full of plants but seaweeds like kelp are, in fact, algae, which is a much simpler organism than a plant like seagrass. The modest makeup of this entity doesn’t detract from its significance; indeed, it is easily the most diverse in terms of species recorded, with an impressive 1,357 identified to date. Incredible varieties of life live here, including the lightbulb sea squirt, the ballan wrasse, all manner of fascinating seaweed and kelp, and the somewhat confusingly named boring sponge – it's not boring because it is tedious but rather because it burrows into rocks.
These rocky habitats, which can be found just above the low tide line (down to about 30 metres deep in clear waters), hold more import than just the home to a coalition of colourful marine life; they can help protect coastlines by buffering strong waves and even play a major role in tackling climate change. Seaweed produces 70% more oxygen than plants on land and absorbs carbon more effectively than trees, so it’s vital that they are safeguarded.
Luckily, kelp forests are abundant throughout the UK, with Seasearch organising dives in conservation zones and protected areas from Wester Ross in the Northern Highlands all the way down to Bembridge on the Isle of Wight. With Seasearch’s help, alongside rewilding or restorative aquaculture projects, these impressive underwater jungles can continue to thrive.
Image credit: MCS and Jo Jamieson
Species highlights
Bloody Henry sea star – if these sea stars are present when you’re diving or snorkelling, you can’t really miss them! Reaching up to 20cm in diameter, they are usually bright purply-red in colour, although they can also come in shades of browns and yellows. See if you can spot a blotchy one that looks like it's been splashed with paint.
Jewel anemone – another brightly coloured inhabitant of the kelp forest, the jewel anemone got its name thanks to its sparkling tentacle tips that resemble … well, jewels. Carpets of pinks, purples, yellows, greens and oranges are formed on rocky overhangs, creating one of the most resplendent sights in UK waters you can hope to see.
Star ascidian – found on the underside of rocks in rock pools or even on kelp fronds, these amazing sea squirts form colonies that look just like a book of pressed flowers. At first glance, each isolated star looks like an individual, but it actually takes three to 12 creatures to create every flowery shape in this impressive mosaic. A truly eye-catching sight.
- Japanese wireweed – originated in Japan; first recorded in Britain in Portsmouth in 1971
- Slipper limpet – originated on the east coast of North America; first recorded in Britain in Essex in the late 1880s
- Leathery sea squirt – originated in the Pacific Northwest; first recorded in Britain in Plymouth in 1953
Image credit: MCS
How to be a volunteer diver and get involved with Seasearch
If you love to get into the water with your dive mask or snorkel on, why not accept a new challenge while you’re doing it? Not only will you have the opportunity to tick some wonderful sights off your underwater bucket list, but you’ll also be playing your part in protecting and tracking the health of our astonishing ocean.
You can make waves by taking part in Seasearch and reporting any sightings you make. It will also vastly improve your own knowledge of marine species where you live.
Angus Jackson, a Data Analyst with Seasearch, had this to say about our article:
"This resource, collated from the amazing Seasearch dataset, will be a valuable asset to support those wanting to learn about the variety of habitats on our seabed, including the fascinating diversity of the plants, algae and animals that live there along with some of the threats that they face. I am sure that holidaymakers around the country will be intrigued to learn more about our fabulous marine life through this illustrated and detailed blog."
To find out more about becoming a Seasearch volunteer, read their in-depth article.
How to spot some of these species in UK rock pools
If you gaze at the picture above (or any rock pool near you, for that matter), you'd be forgiven for thinking that the world beneath the water's surface is a haven of tranquillity. Rather, the opposite is true. With varying temperatures and oxygen levels, not to mention the incoming tides bringing in fresh batches of predators every 12 hours, aquatic rock pool life has its challenges.
But the fact remains that there is plenty of life to be found here, which is great for all the avid rock poolers out there. Head to the low-tide mark to find pools with the most riches but remember to leave everything as you found it, so as not to unbalance the equilibrium of this delicate ecosystem.
For more information, hints and tips on how to find marine critters near you, read our extensive guide to rock pooling.
Explore the coast from the comfort of a self-catering cottage
By now, we imagine you’ve got your wetsuit and flippers on and you are ready to dive straight into some ocean discovery. But where to investigate? The maerl beds of Wester Ross, the kelp forests of Pembrokeshire or the chalk reefs of Norfolk?
Protecting these astonishing habitats is tiring work, but luckily, we’ve got properties all around the Great British Coast where you can rest and recharge in between dives. Dip your toes into our fabulous collection by clicking the button below.
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