Mytilus edulis is fairly common and is abundant in many coastal areas and has therefore not been placed on any conservation list or given any special status.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Blue mussels are most often found in large mussel beds, where they are somewhat protected from predation by virtue of their numbers. The shell of Mytilus edulis acts as a protective layer, though some predator species are able to crush the shell.
Some predators of M. edulis wait until the mussel is forced to open its valves to breathe. The predator then pushes the mussel's siphon into the gap, wedging the mussel open so it can be eaten.
Known Predators:
Mytilus edulis is characterized by a smooth inequilateral shell, usually purple, blue, or dark brown, which features concentric growth lines emanating from the hinge. The interior of the shell is pearl-white. Internally the mantle has a whitish/yellow color, with a posterior adductor scar significantly larger than its anterior adductor scar. Extending from the closed shell are fibrous brown byssal threads for attachment to a surface.
Range mass: 1.4 to 6.5 g.
Range length: 2 to 20 cm.
Average length: 5-10 cm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
The lifespan of Mytilus edulis may vary considerably depending on attachment location. Settline in more exposed coastal areas make individuals significantly more vulnerable to predation, in large part avian. Quality and stability of the substrate also plays a role in the lifespan. Mussels that settle in exposed locations can experience mortality up to 98% per year. Drifting larval and juvenile stages suffer the highest mortality rates.
Range lifespan
Status: wild: 18 to 24 years.
Mytilus edulis is eurythermal and are able to withstand freezing conditions for several months. Blue mussels are well acclimated to a 5 to 20 °C temperature range, with an upper sustained thermal tolerance limit of about 29 °C for adults. Blue mussels do not thrive in salinities of less than 15%, but can withstand wide environmental fluctuations. Their depth ranges from 5 to 10 meters. Usually, M. edulis is found in subtidal and intertidal beds on rocky shores, and remain permanently attached there. The range of Mytilus edulis is limited by the movement of drifting larval and juvenile stages.
Range depth: 1 to 10 m.
Habitat Regions: temperate ; polar ; saltwater or marine
Aquatic Biomes: coastal ; brackish water
Other Habitat Features: estuarine ; intertidal or littoral
Mytilus edulis is found in coastal areas of the northern Atlantic Ocean, including North America, Europe, and the northern Palearctic. They are found from the White Sea in Russia to southern France, throughout the British Isles, with large commercial beds in the Wash, Morecambe Bay, Conway Bay and southwest England, north Wales, and west Scotland. In the west Atlantic, M. edulis occupies the southern Canadian Maritime provinces to North Carolina.
Biogeographic Regions: nearctic (Native ); atlantic ocean (Native ); pacific ocean (Introduced )
The diet of Mytilus edulis consists of phytoplankton, dinoflagellates, small diatoms, zoospores, flagellates, other protozoans, various unicellular algae, and detritus filtered from the surrounding water. Blue mussels are suspension filter feeders and are considered scavengers, collecting anything in the water column that is small enough to ingest.
Animal Foods: eggs; zooplankton
Plant Foods: algae; phytoplankton
Other Foods: detritus ; microbes
Foraging Behavior: filter-feeding
Primary Diet: planktivore ; detritivore
Mytilus edulis has a high tolerance for increased sediment levels and help to remove sediments from the water column. Large blue mussel beds provide habitat and prey for other animals and act as a substrate for algal attachment, increasing local diversity. Blue mussel larvae are an important food source for plantivorous animals as well.
Commensal/Parasitic Species:
People harvest blue mussels as food and they are used in commercial aquaculture. Blue mussels are considered an important food source in some coastal areas and the shells are used in jewelry manufacturing. Blue mussels also help limit algae growth, which has become problematic in the Mediterranean Sea and elsewhere.
Positive Impacts: food ; research and education
There are no known adverse effects of Mytilus edulis on humans.
After the egg is fertilized it turns into a ciliated trocophore larva. The trochophore larva then becomes a veliger, which persists 1 to 1.5 months. In this phase, the larva bears ciliated fan-like protrusions and filter feeds before becoming a juvenile and finding a primary settlement location. The primary settlement location is often located in openings in the substrata, or amongst bryozoans or other filamentous structures and often situated away from mature mussels, presumably to decrease competition. After weeks there, the juvenile has doubled in size and detaches to drift again and find a permanent substrate to which to attach. The young adult will attach to the sea floor with a byssus thread or, if such open substrate is not stable, may attach to another mussel, creating a mussel bed.
Development - Life Cycle: metamorphosis ; colonial growth ; indeterminate growth
Blue mussels have statocysts to aid in geo-positioning and orientation. Blue mussels have chemoreceptors capable of detecting the release of gametes. These chemoreceptors also help juvenile blue mussels avoid settling temporarily on substrata near mature blue mussle, presumably to decrease competition for food.
Communication Channels: chemical
Perception Channels: tactile ; chemical
Mytilus edulis sexes are separate and gametes are shed into the water where fertilization occurs.
Mating System: polygynandrous (promiscuous)
Mytilus edulis spawns from April to September, depending on water temperature, currents, and other environmental factors. In most populations, resting gonads begin to develop from October to November, with gametogenesis occurring throughout winter so that gonads are mature in early spring. A partial spawning in spring is followed by rapid gametogenesis, with gonads maturing by early summer, resulting in a less intensive secondary spawning in late August or September. Larvae spawned in spring can take advantage of phytoplankton blooms. Occurrence of the secondary spawning is opportunistic, depending on favorable environmental conditions and food availability. Gametogenesis, spawning, and reproductive strategies vary with geographic location. An individual female can produce 5 to 8 million eggs, larger individuals may produce as many as 40 million eggs. In optimal conditions, larval development may be complete in less than 20 days but larval growth and metamorphosis between spring and early summer, at 10 °C, usually takes 1 month. Pediveligers can delay metamorphosis for up to 40 days at 10 °C or for up to 6 months in some cases.
Breeding interval: Reproductive output is influenced by temperature, food availability, and tidal exposure and can therefore vary from year to year and from place to place.
Breeding season: Blue mussels generally breed during the spring to late summer.
Range number of offspring: 5000000 to 40000000.
Average number of offspring: 7000000.
Range age at sexual or reproductive maturity (female): 1 to 2 years.
Range age at sexual or reproductive maturity (male): 1 to 2 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization (External ); broadcast (group) spawning
There is no parental care after fertilization.
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female)
“Mytilus edulis, Linné, 1758. Plate 56, fig. 4.
Shell attaining sometimes a large size, oblong-oval or triangular, dilated behind, the beaks anterior and terminal, smooth. Beaks slightly uncinate, close together. Anterior end narrowed, pointed, and usually somewhat inflate, the dorsal margin ascending on the anterior half, the posterior part broadly rounded or almost straight. Posterior end regularly convex, the basal margin straight or more or less concave. Sculpture consisting of fine concentric growth-lines and very fine radiate striæ; under the beaks a small triangular area with prominent ribs corresponding with the hinge-teeth. Epidermis thin, dark olive-brown. Colour deep blackish-blue, sometimes whitish-yellow with brown at the anterior basal part. Interior bluish-white, black outside the pallial line, polished. Margins smooth and sharp. Hinge-plate narrow, oval with 3 or 4 teeth in each valve, which may be reduced to 2 or 1. Ligament external, long and strong, deep-seated. Adductor-scars 2, the anterior very small, behind the umbo; the posterior large, roundish, situate at the upper part of posterior end, and confluent with the long and narrow byssus retractor scar; the anterior retractor scar of the foot is small, oblong, on the dorsal side behind the beak. Pallial line simple. Byssus consisting of a round stalk, from which on all sides the threads of attachment are given off.
Diameter. – Ant.-post., 50 mm. to 120 mm.; dorso-ventral, 25 mm. to 67 mm.: thickness 17 mm. to 40 mm.
Anatomy. – Alex. Purdie, “Studies in Biology for New Zealand Students,” No. 3, 1887.
Hab. – Throughout New Zealand, but more common in the south. Auckland and Campbell Islands.
The species is abundant around the coasts of the North Atlantic, and in the Mediterranean; Strait of Magellan to St. Catharina, Brazil, and extending on the west coast of America to California; Falkland Islands; Kerguelen Island. It is not recorded from Tasmania and Australia.
Remarks. – Specimens from our subantarctic islands are of a very large size. The animal is used as food and for bait. These mussels, like those of other species, contain sometimes pearls of an inferior quality.
Fossil in the Pliocene and Pleistocene of Europe and northern parts of America, and in the Miocene and Pliocene of New Zealand.”
(Suter, 1913)
The blue mussel (Mytilus edulis), also known as the common mussel,[1] is a medium-sized edible marine bivalve mollusc in the family Mytilidae, the mussels. Blue mussels are subject to commercial use and intensive aquaculture. A species with a large range, empty shells are commonly found on beaches around the world.
Systematically blue mussel consists of a group of (at least) three closely related taxa of mussels, known as the Mytilus edulis complex. Collectively they occupy both coasts of the North Atlantic (including the Mediterranean) and of the North Pacific in temperate to polar waters,[2] as well as coasts of similar nature in the Southern Hemisphere. The distribution of the component taxa has been recently modified as a result of human activity. The taxa can hybridise with each other, if present at the same locality.
The Atlantic blue mussel is native on the North American Atlantic coast, but is found intermixed with M. trossulus north of Maine. In Atlantic Canada, M. trossulus was found to have smaller shell growth values than M. edulis and contain less meat than M. edulis.[4] Keeping this in mind, M. edulis, under raft culture conditions, is estimated to have an economic value of 1.7 times M. trossulus.[4] In Europe it is found from French Atlantic coast northwards to Novaya Zemlya and Iceland, but not in the Baltic Sea. In France and in the British Isles, it makes hybrid zones with M. galloprovincialis, and also is sometimes intermixed with M. trossulus.
The genetically distinct lineage of M. edulis present in the Southern Hemisphere has been attributed to subspecies Mytilus edulis platensis (now Mytilus platensis).[3]
Blue mussels are boreo-temperate invertebrates that live in intertidal areas attached to rocks and other hard substrates by strong (and somewhat elastic) thread-like structures called byssal threads, secreted by byssal glands located in the foot of the mussel.
The shape of the shell is triangular and elongated with rounded edges. The shell is smooth with a sculpturing of fine concentric growth lines but no radiating ribs. The shells of this species are purple, blue or sometimes brown in color, occasionally with radial stripes. The outer surface of the shell is covered by the periostracum which as eroded, exposes the colored prismatic calcitic layer. Blue Mussels are semi-sessile, having the ability to detach and reattach to a surface allowing the mollusk to reposition itself relative to the water position.
Right and left valve of the same specimen:
Right valve
Left valve
var. flavida
Right valve
Left valve
Mussels have separate sexes. Once the sperm and eggs are fully developed they are released into the water column for fertilization. Although there are about 10,000 sperm per egg,[6] large proportions of eggs deposited by blue mussels are never fertilized. As few as 1% of larvae that do mature ever reach adulthood. The majority are eaten by predators before completing metamorphosis.
The reproductive strategy seen in blue mussels is characteristic of planktotrophs. By minimizing nutrients in egg production to the bare minimum they are able to maximize the number of gametes produced. If the adult mussels are stressed during the beginning of gametogenesis, the process is terminated.[7] When stressed while fresh gametes are present, adult mussels reabsorb gametes. Larvae viability is also affected by the condition of parents: high water temperatures, pollutants and scarcity of food, during gamete production.[7] The reduction in viability is probably due to the lack of lipid reserves distributed to the eggs.
Larval development can last from 15 to 35 days depending environmental conditions including salinity and temperature, as well as location. Larvae originating from Connecticut mature normally at 15–20 °C (59–68 °F), though at 15 °C (59 °F) normal development occurs at salinities between 15 and 35 ppt and at 35 ppt at 20 °C (68 °F).[8]
The first stage of development is the ciliated embryo, which in 24-hours for fertilization form the trochophore. At this point although mobile, it is still reliant on the yolk for nutrients. Characterized by a functional mouth and alimentary canal the veliger stage also has cilia which are used for filtering food as well as propulsion. A thin translucent shell is secreted by the shell gland forming the notable straight hinge of the prodissoconch I shell. The veliger continues to mature forming the prodissoconch II shell. In the end stage of veliger development photosensitive eye spots and elongated foot with a byssal gland are formed.[9]
Once the pediveliger is fully developed, its foot extends and makes contact with substrate. The initial contact with the substrate is loose. If the substrate is suitable, the larva will metamorphoses into the juvenile form, plantigrade, and attach byssus threads. The mussel will remain in that state until reaching 1-1.5mm in length. This attachment is the prerequisite for the foundation for the blue mussel population. In sheltered environments large masses sometimes form beds which offer shelter and food for other invertebrates. Byssal thread are secreted by byssal glands located in the foot of the mussel, and are made up of polyphenolic proteins which serve as a bioadhesive.[9]
Blue mussels often form aggregations, where they attach to each other using byssus threads. These are collagenous protein strands used for attachment. The type of aggregation depends on population densities.[10] When densities are low, for example in mussel fields – short-lived mussel populations – clumped distribution patterns are seen.[11] The rate of aggregation is aided by the presence of predator cues.[12]
Several explanations for aggregate formation have been offered, such as increase of reproductive success in low density populations,[13] resisting of wave action,[10] and defence against predators.[12] It is, however, still unclear what the main purpose is and aggregation might have different purposes under different circumstances.
Mussel beds are persistent, dense mussel populations. Beds generally form from fields that persist long enough to establish a dense population.[11] In high density aggregations, growth of blue mussels at the centre of the aggregation is reduced, likely due to a reduction in food availability. When possible, mussels will thus migrate to lower densities on larger scales (>7.5 cm), but aggregate on small scales (<2.0 cm).[10] In areas where blue mussels are threatened, such as the Wadden Sea, it is of great importance to enhance the survival of mussel fields, of which mussel aggregates are the primary component.
Predation of blue mussels is greatest during the three weeks it spends as a planktonic larva. During this stage it is susceptible to jellyfish and fish larvae through adults. Once it metamorphoses the mussel is still restricted by predation, with smaller mussels with thinner, weaker shells most affected. Once the shells becomes stronger, blue mussels are preyed upon by sea stars such as Asterias vulgaris as well as by several species of sea gulls. The capability of shell thickening by mussels has become a very effective defense mechanism. In the presence of predators a mussel is able to increase shell thickness 5 to 10 percent, which in turn makes opening the shell take 50 percent more time.[14] Small mussels are also eaten by the dog whelk, Nucella lapillus.[15] The blue mussel is host to a wide range of parasites, but these parasites usually do not cause much damage. Blue Mussels are able to fight off one species of predator at a time such as sea star (Asterias rubens (=Asterias vulgaris)) or green crabs (Carcinus maenas). They use their inducible defenses to strengthen their adductor muscle or grow thicker shells. When faced with two species at a time, they are no longer able to use their defenses and can be killed more easily.[16]
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Blue mussels are filter feeders and play a vital role in estuaries by removing bacteria and toxins. Mytilus edulis is commonly harvested for food throughout the world, from both wild and farmed sources. Mussels are a staple of many seafood dishes in various cuisines including Spanish (especially Galician), Portuguese, French, Dutch, Belgian, Italian and Turkey as midye dolma. They are also commonly used as lab animals. Blue mussels were also harvested by the indigenous peoples of North America.[17]
Blue mussels are starting to decline in areas such as the Gulf of Maine. Historical references have shown a decrease of about 40 percent in the last fifty years.[18] This can cause a future problem because mussels are foundation species providing homes and protecting other small animals in the intertidal zone like small fish as well as filtering the water. Mussels filter out bacteria, metals, and toxins, that would increase significantly without mussels around.[19] Ocean acidification due to increasing atmospheric carbon dioxide is projected to reduce the growth and survival of blue mussels; in turn, this could drastically reduce their positive impact on coastal water quality.[20]
Live blue mussels on a rocky substrate
Numerous empty blue mussel shells on a beach in Iceland
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Live blue mussels
Mussels and cheese gratin
Blue mussel sculpture at Conwy, North Wales near Conwy Castle
The blue mussel (Mytilus edulis), also known as the common mussel, is a medium-sized edible marine bivalve mollusc in the family Mytilidae, the mussels. Blue mussels are subject to commercial use and intensive aquaculture. A species with a large range, empty shells are commonly found on beaches around the world.
