Breadcrumbs
South West Undersea Landscape
Washed in clear Atlantic waters, which sometimes bring visits from leatherback turtles, the undersea landscape of the South West includes many rocky reefs, pinnacles and undersea ledges covered in a close carpet of colourful living sponges, corals and sea squirts. In between are sheltered sandy bays such as Kimmeridge and Babbacombe, where cuttlefish and seahorses feed. Basking sharks often cruise offshore in the plankton stream and seagrass meadows lie in sheltered coves and estuaries. Kelp forests shelter many fish while pink sea fan corals occur from Dorset to North Devon.
This area is home to:
- Basking sharks, who find the seas around the south-west peninsula an excellent feeding ground. These gentle giants weigh up to 7 tonnes but eat only plankton.
- The largest hole in the ocean floor. Hurd Deep in the western English Channel is 50 km long and reaches a maximum depth of 172 metres.
- A unique bed of burrowing sea cucumbers off the Dorset coast which wave their tentacles in the water to catch floating fragments of food and then wipe them clean with their ‘mouths’ before retracting into the gravel.
- The 37 sea caves of Lundy, some of which have ‘beaches’ at the far end used by grey seals to give birth to their pups.
- Dense forests of pink sea fan coral in Plymouth Sound and Lyme Bay. In other places around the south-west coast, this particular coral is scattered across reefs like trees in parkland.
- Seaweed hotspots such as Kimmeridge Bay in Dorset which boasts a dazzling array of bright pink, green and iridescent-blue algae.
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Panorama
Click the numbers on the image below to find out more about the diverse range of species and habitats.
1. Lundy Island - a marine nature reserve full of undersea wildlife
The island of Lundy in the Bristol Channel boasts over 300 species of seaweeds and has 37 sea caves. The ‘beaches’ at the far ends of some caves are used by grey seals to give birth to their pups. [back to panorama]
2. Land's End
Water sweeping southwards past Land’s End comes from the warm Atlantic Gulf Stream. The seafront which follows the coast here sweeps up nutrients from deep water and creates a swirling soup of plankton which attracts small fish such as sand eels. These in turn attract diving birds, including puffins, as well as predatory fish like mackerel and also dolphins, porpoises and whales.
The rich reefs of Land’s End contain green, pink, orange and yellow jewel anemones and there are important sea caves along this part of the Cornish coast. Common seals, which are rare in the south west, and bottlenose dolphins have been sighted here. [back to panorama]
3. Portland Bill
From Portland Bill to Land’s End and the area south of this, the seabed slopes away from the coast quite steeply to a depth of 50 metres. Beyond this, the gradient decreases and a gentle slope continues to depths of 100-120 metres. There are strong currents. [back to panorama]
4. Basking shark - the biggest fish in British seas
The seas around the southwest peninsula are a favoured feeding ground of the basking shark, which in summer will venture into waters within sight of the shore. A gentle giant, and the largest fish to be found in the coastal waters of the British Isles, it measures up to 12 metres, and weighs up to 7 tonnes. Basking sharks feed on animal plankton (mostly tiny shrimp and crab-like creatures), filtering 1,000 to 2,000 cubic metres of seawater per hour, through enormous sieve-like gills.
Up to 70 basking sharks at a time have been sighted over the Hurd Deep and around the Lizard following plankton carried along by the Gulf Stream. [back to panorama]
5. Ocean sunfish - an increasingly frequent tropical visitor to our waters
Sunfish, the largest of all bony fish, may reach over 3m (10ft) in length and have a bizarre appearance. With a round, flattened shape, the sunfish has a large, blunt head and an indistinct tail. The triangular fins stick out, top and bottom, and the small mouth with its fused teeth forms a parrot-like 'beak'. Sunfish feed extensively on jellyfish and often float on their sides in surface waters, sunbathing. They are sometimes mistaken for sharks, as the dorsal fin may stick out of the water. [back to panorama]
6. Harbour porpoise - a shy cousin of the dolphin
In inshore waters the harbour porpoise may be seen around the coasts of Cornwall and north Devon, mainly between September and December. It has a blunt short-beaked head and is generally dark grey on the back and white on the belly. [back to panorama]
7. Kimmeridge Bay seaweed hotspot
Kimmeridge Bay in Dorset boasts a dazzling array of bright pink, green and iridescent blue algae which flourish in the shallow waters. There are over one-hundred different species within a three-mile section of coast. Unusually, the area is not dominated by the large brown kelp weed and this has allowed many species of unusual algae to thrive.
At Kimmeridge Bay there is also a unique bed of burrowing sea cucumbers which wave their tentacles in the water to catch floating fragments of food before wiping them clean in their ‘mouths’ and retracting into the gravel. [back to panorama]
8. Red band fish
This rare fish is unmistakeable. It is long and thin with a pointed tail and fins which stretch almost the entire length of its body. The back and sides are red in colour and the belly is orange or yellowish. Red band fish have large silvery eyes. They burrow into clean sands, such as that found at Lundy, in Torbay and Lyme Bay, and in Portland Harbour and live in vertical burrows singly or in small groups. [back to panorama]
9. Turtles
Migrating leatherback and loggerhead turtles are regularly sighted swimming west of Land’s End, probably visiting the area to feed on its rich crop of jellyfish. [back to panorama]
10. Maerl - fragile beds of coral-like red algae amongst which live millions of tiny sea creatures
Maerl beds are a speciality of the south-west undersea landscape - the largest expanses occur in the Fal Estuary and Falmouth Bay.
Composed of a mixture of three species of coral-like red algae, maerl grows as a network of twig-like ‘nodules’. Beneath the upper pink crust-like layer, the maerl branches create a delicate three-dimensional lattice which allows seawater to penetrate the seabed to a depth of several tens of centimetres, creating conditions where dozens of sea creatures thrive. The living maerl plant is typically pink or purple and very slow-growing. Large ‘nodules’ of maerl may be some of Europe’s oldest plants. The dead material at the base of maerl beds may have lain there untouched for 8,000 years. [back to panorama]
11. Cuttlefish - the intelligent and canny cuttlefish can change its colour for camouflage
Cuttlefish are found in the seagrass beds, close to sheltered shores and also in the Hurd Deep and Bigbury Bay. They can change colour very rapidly, especially when threatened, and may also take on the colour or patterning of their background. Cuttlefish attach their eggs to the seagrass, like bunches of black grapes under the stems. [back to panorama]
12. Seahorses live amongst the dense underwater meadows of seagrass
The seahorse has a very distinctive shape with the head set at an angle to the body. The trunk of the body is short whilst the tail is tapering and curled. These creatures can be up to 15cm in length and have a prominent spine above each eye. They are variable in colour – brown, orange, purple or black, sometimes with pale blotches. [back to panorama]
13. Seagrass meadow - an underwater 'grassland' providing shelter and food for other creatures
Seagrasses grow in sunlit shallow coastal areas, often forming dense underwater meadows. These habitats provide shelter and food for a variety of other species such as seahorses, hermit crabs, sea slugs and cuttlefish.
The most extensive seagrass meadows of this region occur in the Fleet lagoon, near Portland. [back to panorama]
14. Kelp forest - tall seaweed, providing food and shelter to many creatures including the subtropical trigger fish
Spectacular underwater rocks and reefs, many of which rise steeply from the deep seabed to within a few metres of the surface, occur at many sites around the south-west peninsula. Here the shallows are often dominated by waving kelp forests and other seaweeds. [back to panorama]
15. Bottlenose Dolphins
Bottlenose dolphins favour prominent headlands and enclosed bays, and are seen throughout the year. Sightings have come from many parts of the south west including Durlston in Dorset, where it is believed they may live much of the time, as well as Lyme Bay, Tor Bay, Penzance Bay, the Land’s End peninsula and St Ives Bay. [back to panorama]
16. Jellyfish
West of Land’s End there is a rich crop of jellyfish, and migrating leatherback and loggerhead turtles are regularly sighted swimming in the area to feed on this crop. [back to panorama]
17. Mackerel
The submarine landscapes of the southwest support 181 types of fish. Mackerel is one of many species fished commercially in this region. It is attracted to the area by the sand eels and other small fish which, in turn, have come to feed on the plankton stirred up by the sea fronts that occur off the coast. [back to panorama]
18. Sea bass
Sea bass can often be found close to the shore. It is a strong swimmer and therefore doesn’t mind agitated water or surf. [back to panorama]
19. Spider crabs - other crabs found here include edible crab, velvet swimming crab, shore crab
Many types of crab are found on the rocky reefs off the southwest coast. At Mewstone Ledges there are deep gullies full of spider crabs which are reddish-brown with a pear-shaped shell that may be encrusted with other invertebrates.
The velvet swimming crabs are fast moving, grow to about 8 cm in length and have stalked red eyes. They have, as the name suggests, a fine velvet texture. [back to panorama]
20. Leopard-spotted goby shelter in undersea caves and crevices
Leopard-spotted goby are known to shelter in Garfish Cave. They are 12-13 cm long, pale fawn or light brown in colour, with orange, red or black spots all over the head and body and a distinctive black spot at the rear of the first dorsal fin. [back to panorama]
21. Rocks and reefs
Rocks and reefs encrusted with lush growths of anemones, sponges and corals such as dead men's fingers, Devonshire cup coral and jewel anemones. [back to panorama]
22. Pink sea fan forests - a fragile slow-growing coral which can live for up to 80 years
The delicate and slow-growing pink sea fan coral is found all around the south-west peninsula from Kimmeridge in Dorset to Coombe Martin in Somerset. This branching coral is related to many tropical corals and ranges from white to deep pink in colour, reaching up to 80 cm in height. Pink sea fans usually grow at right angles to the prevailing water currents, and are fixed to the seabed by a ‘holdfast’ like kelp. Once established it stays in the same spot and may live for up to 80 years, growing at around 10 mm a year. The pink sea fan feeds by using anemone-like ‘polyps’ to capture zooplankton (small floating animals) from the water flowing by. [back to panorama]
23. Conger eel nearby
During the day, conger eels are found in holes or crevices on rocky or sandy bottoms and in wrecks and other artificial environments. They become more active at night when they leave their resting places to hunt. Many congers are found at depths of 500 m and will go down as far as 4000 m to spawn. These eels are long, powerful fish with scaleless, smooth skin and are usually around 2 m long. [back to panorama]
24. Lobster and sea urchins nearby
Lobsters are part of a rich diversity of sealife supported by the network of reefs. Sea caves provide an important shelter where, if they escape being fished, lobsters can grow to a large size and live for up to 80 years.
Edible sea urchins are also found amongst the reefs. [back to panorama]
25. Plaice - living on the sandy seabed
Plaice are typical flatfish, oval in shape and often seen on sandy patches in rocky areas. They have bright orange or red spots on the upper side and spend much of their time lying quietly on the bottom, often partly buried. They can change their colour to suit the bottom. Commercially, plaice are an important fish. [back to panorama]
26. Sand mason worms - build tubes up to a foot long from grains of sand
The sand mason worm grows up to 30 cm in length and is yellow, pink and brownish in colour. It makes a tube out of sand grains and shell fragments, which has a frayed end that protrudes above the sand. Using its crown of white tentacles, the sand mason worm traps particles of food. [back to panorama]
27. John Dory fish - with its distinctive black spot!
This fish has a compressed body rather like a dinner-plate and grows up to 70 cm in length. The body is golden brown colour with dappled markings and a striking dark spot in the middle of the body. John Dory fish are very good at stalking which compensates for their lack of speed. Having stalked their prey, they then engulf it using an extendable mouth. [back to panorama]
28. Sea beard
Sea beard is found attached to shells and stones on sandy bottoms. It looks like orangey seaweed but is actually colonies of tiny animals. It consists of up to 50 thick, stiff, erect, stems which grow to 25 cm tall from a fibrous mass of roots. Each stem bears a bundle of 6-10 whorled side branches. [back to panorama]
29. Cuckoo wrasse - iridescent blue and orange fish
Cuckoo wrasse are one of number of fish found on the rocky reefs. The females are rose-pink or orange-red. The males have a blue striped head and back, with bright blue markings on the fins – the rest of the body and fins are orange. [back to panorama]
30. Hurd Deep - a deep underwater valley located in the western English Channel
The Hurd Deep is an enormous hole in the ocean floor. Fifty kilometres long, it reaches a maximum depth of 172 metres. [back to panorama]