List of marine molluscs of Ireland (Bivalvia) facts for kids

This article lists the amazing marine bivalves found in the waters around Ireland. It's part of a bigger list about all the marine molluscs living here.

These bivalves live in different parts of the ocean. Some are found on the continental margin (which is like the edge of the land underwater, 200–500 meters deep). Others live in the bathyal zone (500–2000 meters deep) or even the super deep abyssal zone (2000–4000 meters deep). You can find them in areas like the Rockall Basin, Porcupine Seabight, and the Celtic Sea.

What are Bivalves?

Bivalves are a type of mollusc that have two shells hinged together. Think of clams, oysters, and mussels! These shells protect their soft bodies. They get their name "bivalve" because "bi" means two, and "valve" means shell.

How Bivalves Live

Most bivalves live in the ocean, but some can be found in fresh water. They usually stay in one place, either buried in the sand or attached to rocks. They are "filter feeders," which means they suck in water and filter out tiny bits of food like plankton.

Types of Bivalves in Ireland

Scientists group living things into categories to understand them better. This list follows a system created by experts in 2010. Here are some of the main groups of bivalves found off the coast of Ireland:

Protobranchia: Ancient Bivalves

The Protobranchia are a very old group of bivalves. They often have small, delicate shells.

Nuculoida Order

This group includes bivalves like those in the Nuculidae family. They are often found buried in soft mud.

• Ennucula tenuis
• Nucula nucleus (Linnaeus, 1758)
• Nucula sulcata (Bronn, 1831)
• Nucula tumidula (Malm, 1861)

Nuculanoida Order

This order contains families like Nuculanidae and Malletiidae. Many of these bivalves live in deeper waters.

• Ledella messanensis (Jeffreys, 1870)
• Nuculana minuta (Müller, 1776)
• Yoldiella lucida (Lovén, 1846)
• Malletia johnsoni (Clark, 1961)

Pteriomorpha: Winged Shells

The Pteriomorpha group includes many well-known bivalves like mussels, oysters, and scallops. Their shells often have a wing-like shape.

Arcoida Order

This order includes the Arcidae family, known for their ribbed shells.

• Arca tetragona (Poli, 1795)
• Bathyarca pectunculoides (Scacchi, 1835)

The Glycymerididae family has species like Glycymeris glycymeris (Linnaeus, 1758), which has a rounded, thick shell.

Mytiloida Order: Mussels

The Mytilidae family is where you'll find the mussels!

• Modiolus modiolus (Linnaeus, 1758) - often called the horse mussel.
• Mytilus edulis (Linnaeus, 1758) - the common blue mussel you might eat!
• Mytilus galloprovincialis (Lamarck, 1818) - another common mussel.

Pterioida Order: Oysters and Pearl Oysters

This order includes the Pteriidae family, which has pearl oysters.

• Pinctada imbricata (Roding, 1798) - One shell was found in a bait pot at Loher Beach, Waterville, County Kerry.

The Ostreidae family contains true oysters.

• Crassostrea gigas (Thunberg, 1793) - the Pacific oyster.
• Ostrea edulis (Linnaeus, 1758) - the European flat oyster.

Limoida Order: File Clams

The Limidae family includes file clams, which can sometimes "swim" by flapping their shells.

• Acesta excavata (J C Fabricius, 1779)
• Limaria hians (Gmelin, 1791)

Pectinoida Order: Scallops

The Pectinidae family is home to the scallops, famous for their fan-shaped shells.

• Aequipecten opercularis (Linnaeus, 1758) - the queen scallop.
• Mimachlamys varia (Linnaeus, 1758) - a colorful scallop.
• Pecten maximus (Linnaeus, 1758) - the great scallop, a very popular seafood.

Heteroconchia: Diverse Bivalves

The Heteroconchia is a very large and diverse group of bivalves, including many common clams.

Carditoida Order

This order includes the Astartidae family.

• Astarte sulcata (da Costa, 1778)

The Thyasiridae family has some unique bivalves.

• Adontorhina keegani (Barry & McCormack, 2007) - only found near the Porcupine Bank, west of Ireland.
• Thyasira flexuosa (Montagu, 1803)

Anomalodesmata Order

This group includes the Pandoridae and Thraciidae families.

• Pandora inaequivalvis (Linnaeus, 1758)
• Thracia convexa (W Wood, 1815)

Septibranchia: Carnivorous Bivalves

The Septibranchia are a special group of bivalves that are often carnivorous, meaning they eat other small creatures. They have adapted gills that help them catch prey.

Verticordioidea Superfamily

This group includes the Verticordiidae and Cuspidariidae families. Many live in very deep waters.

• Halicardia flexuosa (Verrill & Smith, 1881) - found in deep sea (bathyal and abyssal zones).
• Cuspidaria cuspidata (Olivi, 1792)
• Myonera alleni (Poutiers & Bernard, 1995) - found in the Bay of Biscay, Porcupine Sea Bight, and Rockall Trough.

Veneroida Order: Common Clams

This is a very large order with many familiar bivalves.

Lucinoidea Superfamily

The Lucinidae family is part of this group.

• Lucinoma borealis (Linnaeus, 1758)

Galeommatoidea Superfamily

This superfamily includes several families of small bivalves, like Lasaeidae and Montacutidae. Many live in close relationships with other marine animals.

• Lasaea adansoni (Gmelin, 1791)
• Montacuta substriata (Montagu, 1808)

Hiatelloidea Superfamily

The Hiatellidae family includes bivalves that often bore into rock or other hard surfaces.

• Hiatella arctica (Linnaeus, 1758)

Arcticoidea Superfamily

The Arcticidae family contains the famous ocean quahog.

• Arctica islandica (Linnaeus, 1767) - This bivalve is known for living for an incredibly long time, sometimes over 500 years!

Cardioidea Superfamily: Cockles

The Cardiidae family is where you'll find cockles, which are popular on sandy beaches.

• Acanthocardia echinata (Linnaeus, 1758)
• Cerastoderma edule (Linnaeus, 1758) - the common cockle.

Veneroidea Superfamily: Venus Clams

The Veneridae family includes many types of "Venus clams," known for their strong, often beautifully patterned shells.

• Chamelea striatula (da Costa, 1778) - the striped venus shell.
• Dosinia exoleta (Linnaeus, 1758) - the rayed artemis.
• Venus verrucosa (Linnaeus, 1758) - the warty venus.

Tellinoidea Superfamily: Tellins and Razor Shells

This group includes the Tellinidae and Solenidae families.

• Macoma balthica (Linnaeus, 1758) - the Baltic tellin.
• Tellina tenuis (da Costa, 1778)
• Ensis ensis (Linnaeus, 1758) - a type of razor shell.

Mactroidea Superfamily: Trough Shells

The Mactridae family includes trough shells.

• Lutraria lutraria (Linnaeus, 1758) - the common otter shell.
• Mactra stultorum (Linnaeus, 1758) - the fragile surf clam.

Myoida: Boring Bivalves

The Myoida order includes bivalves that can bore into wood or other materials.

Myoidea Superfamily

The Myidae family includes soft-shell clams.

• Mya arenaria (Linnaeus, 1758) - the sand gaper.
• Mya truncata (Linnaeus, 1758) - the blunt gaper.

Pholadoidea Superfamily: Shipworms and Piddocks

This group contains the Pholadidae (piddocks) and Teredinidae (shipworms) families.

• Pholas dactylus (Linnaeus, 1758) - the common piddock, which can bore into rock.
• Teredo navalis (Linnaeus, 1758) - the shipworm, known for boring into wood, including old ships!