SCOTLAND: The Big Picture / Blue mussels (Mytilus edulis) with encrusting marine life, Sula Sgeir, Scotland. UK, July

SCOTLAND: The Big Picture / Curled octopus (Eledone cirrhosa) amongst a horse mussel bed (Modiolus modiolus) Shetland, Scotland, UK, August.

Alex Hyde / Colony of Common Mussels (Mytilus edulis) growing on striated rock formation exposed at low tide. Cornwall, England, UK. Highly commended in the Coast and Marine Category of the British Wildlife Photo...

Nick Upton / Juvenile Edible crab (Cancer pagurus) among Common mussels (Mytilus edulis) in a rock pool with a Rock goby (Gobius paganellus) in the background, Gower Peninsula, Glamorgan, Wales, UK, August.

David Hall / Acorn barnacles (Semibalanus cariosus) and (Balanus glandula), Mussels (Mytilus sp.), and Plumose anemones (Metridium senile) underwater at high tide, Seven Tree Island, Browning Pass, Queen Charlotte...

David Hall / Purple and Ochre sea stars (Pisaster ochraceus) preying on Pacific blue mussels (Mytilus trossulus). Also seen are Green Surf Anemones (Anthopleura xanthogrammica), Short Plumose Anemones (Metridium s...

Orsolya Haarberg / Coastal rocks covered by Blue mussel (Mytilus edulis) shells. Tomma Island, Helgeland Archipelago, Norway.

Nick Upton / Dense bed of Common mussels (Mytilus edulis) exposed at low tide on rocks fringing a sandy beach, Godrevy, Cornwall, UK, April.

SCOTLAND: The Big Picture / Yellow sun star (Solaster endeca) amongst Brittle stars (Ophiothrix fragilis) on a Horse mussel bed (Modiolus modiolus) Sheltand Islands, Scotland, UK, September.

SCOTLAND: The Big Picture / Horse mussel bed (Modiolus modiolus) with Brittle stars (Ophiothrix fragilis),Edible crab (Cancer pagurus) and Northern sea urchin (Strongylocentrotus droebachiensis) Sheltand Islands, Scotland, UK, S...

SCOTLAND: The Big Picture / Horse mussels (Modiolus modiolus) with brittle stars (Ophiothrix fragilis), Shetland, Scotland, UK, August.

Nick Upton / Kelp fly (Fucellia maritima) on Mussel (Mytilus edulis) shell exposed at low tide. Treyarnon Bay, Cornwall, England, UK. September.

Paul Williams / Ochre starfish (Pisaster ochraceus) Goose barnacles (Pollicipes polymerus) California mussel (Mytilus californianus) and Giant green anenome (Anthopleura xanthogrammica) in rock pool, Vancouver Island...

Paul Williams / Ochre starfish (Pisaster ochraceus), Goose barnacles (Pollicipes polymerus) and California mussel (Mytilus californianus) in rock pool, Vancouver Island, British Columbia, Canada, July.

Paul Williams / Goose barnacles (Pollicipes polymerus) and California mussel (Mytilus californianus), Vancouver Island, British Columbia, Canada, June.

Paul Williams / Goose barnacles (Pollicipes polymerus) and California mussel (Mytilus californianus), Vancouver Island, British Columbia, Canada, June.

Paul Williams / Ochre starfish (Pisaster ochraceus) California mussel (Mytilus californianus) and Giant green anenome (Anthopleura xanthogrammica) in rock pool, Vancouver Island, British Columbia, Canada. July.

Werner Bollmann / Blue mussels (Mytilus edulis) Vestvagoy, Norway, March 2012.

Sandra Bartocha / Blue Mussels (Mytilus edulis) Bohuslan Archipelago, Sweden, July 2015.

Solvin Zankl / Diver fisherman collecting Chilean blue mussel (Mytilus chilensis) Comau Fjord, Patagonia, Chile, Pacific Ocean, January

Solvin Zankl / Diver fisherman collecting Chilean blue mussel (Mytilus chilensis) Comau Fjord, Patagonia, Chile, Pacific Ocean, January

Solvin Zankl / Local fishermen and boats setting out to collect Chilean blue mussels (Mytilus chilensis) Comau Fjord, Patagonia, Chile, January 2013

Solvin Zankl / Yellow encrusting anemone (Parazoanthus elongatus) and Chilean blue mussel (Mytilus chilensis) Comau Fjord, Patagonia, Chile Pacific Ocean

Solvin Zankl / Diving fisherman collecting Chilean blue mussel (Mytilus chilensis) Comau Fjord, Patagonia, Chile, Atlantic Ocean

SCOTLAND: The Big Picture / Horse mussel (Modiolus modiolus) bed with Brittlestars (Ophiothrix fragilis) and Edible crab (Cancer pagurus), Shetland, Scotland, UK, September.

SCOTLAND: The Big Picture / Scientists from Heriot Watt University measuring Horse mussels (Modiolus modiolus), a priority marine feature. Within a Marine Protected Area, Shetland, Scotland, UK, September 2012.

SCOTLAND: The Big Picture / Scientist from the Heriot Watt scientific dive team collecting Horse mussel (Modiolus modiolus) samples to assess biodiversity. Within a Marine Protected Area, Shetland, Scotland, UK, September 2012.

SCOTLAND: The Big Picture / Horse mussel (Modiolus modiolus) bed with brittle stars and crabs, Shetland, Scotland, UK, September.

Ernie Janes / Sea shells on beach including Razor clams (Ensis siliqua) Mussels (Mytilus) Norfolk, England, UK, February.

Michael Hutchinson / Mediterranean mussels (Mytilus galloprovincialis) and limpets on rock, Cape Province, South Africa, December.

Michael Hutchinson / Mediterranean mussels (Mytilus galloprovincialis) and limpets on rock, Cape Province, South Africa, December.

Michael Hutchinson / Mediterranean mussels (Mytilus galloprovincialis) and limpets on rock, Cape Province, South Africa, December.

Michael Hutchinson / Cape sea urchin (Parechinus angulosus) and Mediterranean mussels (Mytilus galloprovincialis) on rock, Cape Province, South Africa, December.

Richard Robinson / Green-lipped mussels (Perna canaliculus) covered in anemones, barnacles and a starfish in Breaksea Sound, Fiordland National Park, New Zealand.

Richard Robinson / Green-lipped mussel shells (Perna canaliculus) in Breaksea Sound, Fiordland National Park, New Zealand.

Alex Hyde / Acorn barnacle (Semibalanus balanoides) growing on shell of Common Mussel (Mytilus edulis), Isle of Skye, Scotland, April.

Alex Hyde / Pea Crab (Pinnotheres pisum) inside a Common Mussel (Mytilus edulis). This small crab parasitises a number of bivalve species including mussels, living in the host's mantle cavity. Normandy, France. J...

Cheryl-Samantha Owen / Pacific blue mussels (Mytilus trossulus) Botanical Beach, near Port Renfrew, Vancouver Island, British Columbia, Canada, July.

Jean E. Roche / Reflections in water at mussel farm in the bay of Fos-sur-Mer, Camargue, France, September.

Jean E. Roche / Reflections in water at mussel farm in the bay of Fos-sur-Mer, Camargue, France, September.

Jean E. Roche / Reflections in water at mussel farm in the bay of Fos-sur-Mer, Camargue, France, September.

Nick Upton / Recenty settled young Common mussels (Mytilus edulis) alongside barnacle encrusted adults on rocks exposed on a rocky shore at low tide, Rhossili, The Gower Peninsula, UK, June.

Nick Upton / Common mussels (Mytilus edulis) attached to rocks exposed at low tide, Trebarwith strand, Cornwall, UK, April.

Nick Upton / Common mussels (Mytilus edulis) dense colony attached to rocks exposed at low tide, Trebarwith strand, Cornwall, UK, April.

Nick Upton / Common mussels (Mytilus edulis) dense colony attached to rocks exposed at low tide, Trebarwith strand, Cornwall, UK, April.

Nick Upton / Common mussels (Mytilus edulis), Dog Whelks (Nucella lapillus) and Common barnacles (Semibalanus balanoides) attached to rocks exposed at low tide, Rhossili, The Gower peninsula, Wales, UK, June.

Nick Upton / Common mussels (Mytilus edulis) dense colony attached to rocks exposed at low tide, Trebarwith strand, Cornwall, UK, April.

Nick Upton / Common mussels (Mytilus edulis) attached to rocks exposed at low tide, Trebarwith strand, Cornwall, UK, April.