Molluscs are among the largest animal phyla in the ocean. The three main groups of molluscs are bivalves (shells), gastropods (snails) and cephalopods (squids and octopuses). Smaller groups include polyplacophora (chitons) and scapopoda (tusk shells). Species from all of these groups have been found in Eyjafjörður. All molluscs have a soft body but often also have a hard shell for protection. Otherwise molluscs are very diverse.

Feeding habits among these groups are quite different. Bivalves are primarily filter or detritus feeders. Gastropods are algae scrapers, scavengers or predators on sessile animals. Cephalopods are active predators on fishes and other cephalopods.

Most molluscs are quite small, small snails crawling between rocks on the seashore or small bivalves bury themselves into soft bottom sediments. A few are large enough to be harvested. Species that have been harvested in Iceland are blue mussel, ocean quahog, Iceland scallop and whelk. All are found in Eyjafjörður but only the blue mussel is currently harvested there, or in fact grown. One of the largest mussel farmers in Iceland is located in the island of Hrísey in the middle of the fjord. Other large and edible species found in the fjord are horse mussel, Iceland cockle and soft shell clam.

Cephalopods are rare in the fjord, but some species are residents of the deep waters north of the fjord. Occasionally European flying squid migrates into the fjord and is harvested. The mysterious giant squid has also been found in the fjord.

Kræklingur. (Mynd: Erlendur Bogason) Kræklingur. (Mynd: Erlendur Bogason)

Beitukóngur við eggjaklasann sinn (Mynd: Erlendur Bogason) Beitukóngur við eggjaklasann sinn (Mynd: Erlendur Bogason)