Mytilus: A genus of marine mussels in the family MYTILIDAE, class BIVALVIA. The species MYTILUS EDULIS is the highly edible common mussel.Mytilus edulis: A species of mussel in the genus MYTILUS, family MYTILIDAE, class BIVALVIA, known as the common mussel. It has a bluish-black shell and is highly edible.Bivalvia: A class in the phylum MOLLUSCA comprised of mussels; clams; OYSTERS; COCKLES; and SCALLOPS. They are characterized by a bilaterally symmetrical hinged shell and a muscular foot used for burrowing and anchoring.Gills: Paired respiratory organs of fishes and some amphibians that are analogous to lungs. They are richly supplied with blood vessels by which oxygen and carbon dioxide are exchanged directly with the environment.Mollusca: A phylum of the kingdom Metazoa. Mollusca have soft, unsegmented bodies with an anterior head, a dorsal visceral mass, and a ventral foot. Most are encased in a protective calcareous shell. It includes the classes GASTROPODA; BIVALVIA; CEPHALOPODA; Aplacophora; Scaphopoda; Polyplacophora; and Monoplacophora.Hemocytes: Any blood or formed element especially in invertebrates.Mytilidae: A family of marine MUSSELS in the class BIVALVIA.Ciliophora: A phylum of EUKARYOTES characterized by the presence of cilia at some time during the life cycle. It comprises three classes: KINETOFRAGMINOPHOREA; OLIGOHYMENOPHOREA; and POLYMENOPHOREA.Turbellaria: A class of free-living freshwater flatworms of North America.Microsporea: A class of parasitic FUNGI. Characteristics include spores that are spherical, oval, or tubular in shape and sporoplasm which is uninuclear or binuclear.Animal Shells: The hard rigid covering of animals including MOLLUSCS; TURTLES; INSECTS; and crustaceans.Perna: A genus of freshwater mussel in the family MYTILIDAE, class BIVALVIA. It is found in tropical and warm temperate coastal waters. Most species have green in their shells.Atlantic OceanDNA, Mitochondrial: Double-stranded DNA of MITOCHONDRIA. In eukaryotes, the mitochondrial GENOME is circular and codes for ribosomal RNAs, transfer RNAs, and about 10 proteins.