MARINE INVERTEBRATES- Bivalves
| Bivalves have two shells or 'valves'. They are joined by a 'hinge' along one edge, a flexible ligament that allows them to open and filter feed. |
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Blue Mussel Mytilus edulis chilensis
These dark blue-black bivalve mussels (tend to lighter blue in older shells) are common in sheltered Falklands harbours and inlets where they form dense beds within the low to medium tidal zones, attaching to rocks with threads and sometimes forming clusters. Beaches may appear covered by mats of blue mussels.
The shell is fairly smooth and grows to 9-10cm (3.5-4 inches). It is covered by a thin layer of protein substance which makes it appear black-brown but which peels away when dry. Blue Mussels are an important food source for Oystercatchers, Dolphins and Dominican gulls.
Abroad on neighbouring Southern South America they are known as the ‘Chilean Blue Mussel’ or ‘Montevideo’ Mussel. |
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Ribbed Mussel Aulacomya
Local name: Ribbed Mussel
This is the Falklands largest bivalve mussel, growing up to and around 7 inches (17cm). It is native to the Falkland Islands, Argentina, Chile and Peru. It is also found on the coast of New Zealand and South Africa.
Ribs are deep, brownish black with a purple tinge and darken with age. This is an edible mussel, and grows offshore below the lowest tidal zones on rocky sea beds, often attaching to the kelp to be washed ashore when the holdfasts break off. |
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Clam Humilaria exalbida
Buff –white large bivalves with thick concentric ribs often growing to around 8cm (3inches) diameter. Clams are found on sloping shelved sandy beaches buried deep below the surface in the sand. They are edible but rarely eaten.
Strange. |
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Patagonian Scallop Zygochlamys patagonica
The Patagonian scallop, a bivalve, is found on the Falklands Islands shelf and around the tip of South America from 42°S in the Pacific to 35°S in the Atlantic. It favours sandy and muddy areas a depths ranging from 40to 200m.Shells frequently wash up on Falklands coasts.
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Sources include: Falkland Islands State of the Environment Report 2008 Otley H, Munro G, Clausen A, Ingham B. A Field Guide to the Wildlife of The Falkland Islands and South Georgia - Ian J Strange, Dillwyn
Photographic credits: Robert Maddocks, shells thanks to Tracy Evans
Photographs and Images Copyright: The images on this site have been bought under licence or have been used with the permission of their owners. They may not be copied or downloaded in any form without their owner's consent. |
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