Common Mussel (Mytilus edulis) Exmouth, Devon. August 2019 © Pete Hillman.
I have shown the two gaper shells on one post to illustrate how different they are, beginning with the Sand Gaper above.
Sand Gaper (Mya arenaria)
A large and robust bivalve, the shell is oval in shape, the anterior end rounded, the posterior end more pointed. It has concentric ridges and is off-white, grey or light brown in colour. Shell length 15cm.
The Sand Gaper burrows to a depth of 50cm into mud and sandflats, where it filters organic matter from sea water. It is often found in estuaries, and is widespread and locally common.
Blunt Gaper (Mya truncata)
A thick-shelled, robust bivalve, rectangular in shape with a truncate posterior margin. It also has numerous concentric lines and is off-white in colour. Shell length up to 70mm.
It is commonly found in estuaries where it buries itself to a fair depth. Widespread and locally common, especially on the east coast of Britain.
Photographs taken April 2013, Llandudno, Wales. Camera Nikon Coolpix P500. © Pete Hillman 2013.
The shell is a rounded-oval, although the posterior more angled. The colour is variable from pink to purple, yellow and white. Width 25mm.
It is found on the lower shore in muddy sand, and also in estuaries. Common and widespread.
Photographs taken June 2012, Llandudno, Wales. Camera Nikon Coolpix P500. © Pete Hillman 2012.
The shell has numerous fine, concentric rings and grooves. It is dirty white, yellowish or greyish in colour, and is flat, thin and delicate in form. Length 6.5cm.
It is found in sheltered, brackish habitats, like estuaries and muddy shores where it burrows up to 20cm, leaving behind a star-shaped tell-tale impression on the surface. It is a deposit-feeder, and when the inhalant siphon is extended it is often eaten by crabs, fish and wading birds, but it is regrown fairly quickly. Common and widespread all around the UK.
Photographs of Peppery Furrow (Scrobicularia plana), taken August 2011, Saundersfoot, Wales. © Pete Hillman 2011. Camera used Panasonic Lumix DMC-FZ38.
The colour of the shell is pale cream or yellowish, usually marked with three prominent radiating brown bands. It is fairly thick and has fine concentric ridges. Length 4cm.
It is found buried in the lower shore to sublittoral, and it can live up to 10 years. Common and widespread on all coasts, except the south-east coast of England.
Photographs of Striped Venus Clam (Chamelea gallina), taken August 2011, Saundersfoot, Wales. © Pete Hillman 2011. Camera used Panasonic Lumix DMC-FZ38.
This mollusc has a shiny white to yellow, purple or greyish-brown slender wedge-shaped shell. Growth stages show as pale bands. The inner surfaces are tinted white, purple, yellow or orange. Length up to 38mm.
Found on the middle to lower shore where it burrows into coarse sand and lives just below the surface. The Banded Wedge Shell is a filter feeder, and when the tide is in it extracts food particles from the water via a syphon. Common and widespread on all British and Irish coasts, but less common further north on Scottish coastlines.
Photographs of Banded Wedge Shell (Donax vittatus), taken August 2011, Saundersfoot, Wales. © Pete Hillman 2011. Camera used Panasonic Lumix DMC-FZ38.
The Necklace Shell has a buff to pale yellow shell with a spiral row of brownish marks near its upper edge. Similar to Alder’s Necklace Shell which is smaller and darker. Shell height up to 3cm.
It is found buried in the lower shore, in sheltered to moderately exposed sand. It feeds on small bivalves by drilling a round hole through its shell. Common and widespread along all British coasts.
Photographs of Necklace Shell (Polinices catenus), taken August 2011, Saundersfoot, Wales. © Pete Hillman 2011. Camera used Panasonic Lumix DMC-FZ38.
The shell is elongate, thin and brittle. There are numerous fine concentric lines, with a group of fine radiating striae. It is white or light brown, light olive or yellow. The hinge and ligament is positioned about a third of the way along the length of the mollusc. Length up to 130mm.
It burrows deeply in fine to medium course sands in the lower shore and shallow sublittoral. Found on the south-west coasts of England, Wales and Ireland.
Photographs of Bean Solen (Pharus legumen), taken August 2011, Saundersfoot, Wales. © Pete Hillman 2011. Camera used Panasonic Lumix DMC-FZ38.
Have you ever wondered what the underside of a limpet looked like? Note the large muscular foot, the relatively small mouth above, and the tentacles either side.
The Common Limpet has an ashen-grey or greenish-blue shell, sometimes with a yellow tint, and with radiating ridges. It is conical with an almost central apex. The shell is often covered in barnacles. The sole of the foot is yellowish or orange-brownish with a green tinge. Shell length 6cm. They are fairly long-lived, up to 15 years.
It inhabits the intertidal zone, clinging tightly to rocks along the shore or in rock pools, and with its thick shell it is able to withstand the pounding ocean waves, exposure to drying out, and attacks from birds or fish. It grazes on algae growing on the rocks beneath the water. It is not ‘stuck’ in one position as it may always appear to be, but follows a mucous trail as it feeds and finds it way back. Scarring maybe evident on the substrate where it has ground it down to get the perfect fit. Common and widespread around the British coasts.
Photographs of Common Limpet (Patella vulgata), taken August 2011, Saundersfoot, Wales. © Pete Hillman 2011. Camera used Panasonic Lumix DMC-FZ38.
Also called the ‘Blue Mussel’, the shells are dark brown, blue-black, or purple in colour. Shell length up to 10cm.
It is found middle to lower shore, and attaches itself to rocks via byssus threads. It will also find crevices in the rocks, or attach themselves to manmade structures like piers and harbour walls. They can form large beds up to 6 layers thick and covering many square kilometres. Mussels are filter feeders of plankton, pumping large amounts of water through their bodies to extract the food.
Very common and widespread all around the British coast.
This is an edible marine mussel which has been harvested by humans for centuries. They are a rich source of protein, and are very important to the marine life ecosystem.
Photographs of Common Mussel (Mytilus edulis), taken August 2011, Saundersfoot, Wales. © Pete Hillman 2011. Camera used Panasonic Lumix DMC-FZ38.
Also called the ‘Edible Periwinkle’, the shell is variable in colour, from black and grey to brown, white or red, and usually patterned with spiral dark lines. It is conical in shape with a pointed apex. This is the largest British periwinkle, but is usually smaller than 50mm.
It favours rocky shores upper to lower zones with a good covering of seaweed. It can also be found in mud-flats or esturaries. The Common Periwinkle is a herbivore which grazes on seaweeds. Widespread and abundant throughout.
Photographs of Common Periwinkle (Littorina littorea) taken June 2012 (top 2 photos) and April 2014 (bottom photo), Llandudno, Wales. © Pete Hillman 2012 and 2014. Cameras used Panasonic Lumix DMC-FZ38 and Nikon D3200, with Sigma 105mm macro lens.
This limpet has a humped, smooth shell with variegation in colour, usually pinkish, orangey, cream or purplish. It has a fairly thick shell with a shelf on the underside, which resembles a slipper. Shell length 5cm. Shell height 2.5cm.
It is found on the lower shore, attached to rocks and other shells, and they form stacks of up to ten individuals or more. They begin life as males, and then change progressively to become females. An introduced species from north-east America in 1887, the Slipper Limpet is quite an invasive species which competes with native oysters for space and food, and is also a threat to Common Mussel beds. Common and widespread.
Photographs of American Slipper Limpet (Crepidula fornicata), taken August 2012, Bournemouth, Dorset, . © Pete Hillman 2012. Camera used Nikon Coolpix P500.
The Dog Whelk’s shell is variable in colour, from white to dark brown, yellow or banded. Thick-shelled, it is broadly conical bearing spiral ridges with a short spire. Shell height 3 to 5cm.
It is a fierce predator of mussels, barnacles and other molluscs. It bores a hole into the prey’s shell using its radula. Its digestive juices dissolve the prey and it sucks it up with its proboscis. It produces yellow egg capsules which are fixed in clusters under rocks. It can live for up to 10 years.
Found in all types of rocky shores from the middle shore downwards, on rocks, under overhangs and in crevices. Common and widespread.
Photographs taken April 2014, Llanduno, Wales, and August 2015, Meadfoot Beach, Torquay, Devon.
Also called the ‘Flat Topshell’, the shell is dull green, cream or grey with broad red-purple diagonal stripes. It is a relatively small flattened topshell with a large round umbilicus (a deep hole on the underside of the shell). Shell length 1.6mm.
Seen on the uppershore in rockpools and on open rocks. This gastropod feeds on microscopic algae, which it grazes from rock surfaces using a brush-like radula on the tongue. Found on the western shores of the UK.
Photographs taken August 2011, Saundersfoot, Wales, and August 2015, Meadfoot Beach, Torquay, Devon.
Also called the ‘Flat Oyster’ or the ‘Native Oyster’, it has a thick, rough textured grey-brown shell. It has a deeply cupped left valve, and a smaller flat right valve. Shell diameter 10cm.
The Common Oyster is the only native oyster, and is an important source of food for humans and other animals and birds. It also produces pearls. It forms beds around the low-water mark of estuaries and open shores, found attached to rocks or other shells. Widely distributed around the British coasts, but less so on the east and north-east coasts. Its population has suffered a sharp decline due to over fishing, pollution and disease.
Photographs taken June 2012, Llandudno Wales and August 2012, Bournemouth.
The colour of the shell of this small snail varies depending on its habitat, and it can be green, orange, yellow, brown or black. There are also banded and chequered patterned forms. The head tentacles of the animal have two lines along them. The shell is finely reticulate. Shell height up to 1.5cm.
Found on the middle to lower shower on large brown seaweeds such as Egg Wrack (Ascophyllum nodosum) and Toothed Wrack (Fucus serratus) on which it feeds. Common on widespread throughout.
Photographs taken August 2015, rockpool, Meadfoot Beach, Torquay, Devon.
Also called the ‘Common Razor Shell’, the shell is dull white with a yellowish tinted pink or purple colour. It is a large species, long and narrow, and the largest European species of razor shell. Length up to 20mm.
It is found on the lower shore buried in a deep vertical burrow from where it filter-feeds organic detritus via a pair of short siphons. It can live up to 20 years. Common and widespread.
Photographs taken August 2011, Saundersfoot, Wales, and August 2012, Bournemouth.