''Geukensia demissa'' is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

mussel Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and Freshwater bivalve, freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other ...

, a

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

in the family

Mytilidae Mytilidae are a family of small to large marine and brackish-water bivalve molluscs in the order Mytilida. One of the genera, ''Limnoperna'', even inhabits freshwater environments. The order has only this one family which contains some 52 gen ...

, the true mussels. This species is native to the

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

coast of North America. The

common names In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of everyday life; and is often contrast ...

for this species include ribbed mussel, Atlantic ribbed marsh mussel and ribbed horsemussel.''Geukensia demissa'' (mollusc)
Global Invasive Species Database. However, the common name ''ribbed mussel'' is also used for the Southern Hemisphere mussel ''

Aulacomya atra ''Aulacomya atra'', called also the Magellan mussel or the ribbed mussel, is a southern species of edible saltwater mussel, a marine bivalve mollusk in the family Mytilidae, the true mussels.Bouchet, P.; Gofas, S. (2011)''Aulacomya atra'' (Mo ...

''. The appearance of the shell is grooved and oval in shape. The interior of this mussel is tinted purple The ribbed shells of this species usually attain a length of 10 cm length, and can be as large as 13 cm. Age can be determined by counting dark growth rings on the shell and mussels typically live 10 – 15 years, but more advanced ages are not uncommon.

Distribution

The ribbed mussel occurs in the coastal waters of

salt marsh A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is dominated ...

habitats from the southern

Gulf of St. Lawrence The Gulf of St. Lawrence () is the outlet of the North American Great Lakes via the St. Lawrence River into the Atlantic Ocean. The gulf is a semi-enclosed sea, covering an area of about and containing about of water, at an average depth of . ...

in eastern

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, south along the western Atlantic coast to Florida. In the Gulf of Mexico this species is replaced by the southern ribbed mussel, '' Geukensia granosissima, and the two species hybridize in southern Florida. The ribbed mussel has been introduced to

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

California California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...

, and

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

Habitat

Ribbed mussels live in the

intertidal zone The intertidal zone, also known as the foreshore, is the area above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species o ...

, attached to hard surfaces or embedded in sediment with the help of their byssal threads. They are typically found in

es where they form dense aggregations with the marsh cordgrass (''

Spartina ''Spartina'' is a taxon of plants in the grass family, frequently found in coastal salt marshes. Its species are commonly known as cordgrass or cord-grass, and are native to the coasts of the Atlantic Ocean in western and southern Europe, north ...

alterniflora'') and each other since aggregating near one another decreases an individual's chance of being preyed on. Ribbed mussels are highly effected by small variations in temperature which makes their placement in the marsh important due to how variable temperature can be in salt marshes. Mussels that are in dense ''Spartina'' patches tended to be warmer than those who were not, and the amount of air flow that mussels receive can make a difference as well. Their position in the depth of the sediment also effects their internal body temperature. Another example of how important microhabitats are for ribbed mussels is tidal height. In higher tidal zones, ribbed mussels do not grow to full potential and there are few out there; however, they tend to be live long and have a better chance of survival. Ribbed mussels face more predation on marsh edges as well. Some of their predators include birds, raccoons, and blue crabs.

Reproduction

Ribbed mussels are

dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...

and sexes can only be determined histologically. They reproduce once per year in Connecticut and South Carolina, however in an introduced population in Venezuela two

spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquati ...

peaks have been observed. Mussels >15 mm are typically reproductive; however, it is not uncommon for mussels up to 35 mm to have no signs of

gametogenesis Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes. Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic d ...

. Their location in the salt marsh plays a role in when they become reproductive because edge ribbed mussels mature at smaller body sizes compared to other mussels. Ribbed mussel

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

e return to the marsh during

recruitment Recruitment is the overall process of identifying, sourcing, screening, shortlisting, and interviewing candidates for jobs (either permanent or temporary) within an organization. Recruitment also is the processes involved in choosing individual ...

, and they tend to settle near marsh edges where there are adult ribbed mussels.

Diet

The ribbed mussel is primarily a

filter feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...

, and they help to clean said area of bacteria, parasites, and heavy metals. They feed on

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater ecosystems. The name comes from the Greek words (), meaning 'plant', and (), meaning 'wanderer' or 'drifter'. Ph ...

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

, and non flagellates to gain nutrients. The speed at which ribbed mussels feed changes with temperature which is partially due to the availability of their food, and they feed more when their environment is warmer. Location also plays a role in filtration rates due to food quality and availability.

Ecological Importance

Ribbed mussels and other shellfish are able to store nutrients in the bodies and shells, through a process that may also remove toxins from the environment, and they can be used as

bioindicator A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sma ...

s for certain pollutants like coliform bacteria. Ribbed mussels have been found with

heavy metals upright=1.2, Crystals of osmium, a heavy metal nearly twice as dense as lead">lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals are generally defined as ...

in their tissues which suggests that they can filter such toxins out of the ecosystem. They also feed on algae, so they could be used to prevent harmful

algal bloom An algal bloom or algae bloom is a rapid increase or accumulation in the population of algae in freshwater or marine water systems. It is often recognized by the discoloration in the water from the algae's pigments. The term ''algae'' encompas ...

s. ''Spartina'' grasses benefit from the presence of mussels because ribbed mussels increase nutrients in sediment that ''Spartina'' need to grow. For example, mussels contribute bioavailable nitrogen in their

pseudofeces Pseudofeces or pseudofaeces are a specialized method of expulsion that filter-feeding bivalve mollusks (and filter-feeding gastropod mollusks) use in order to get rid of suspended particles such as particles of grit which cannot be used as food, ...

. When ribbed mussels form mussel mounds, they are able to stabilize the ground to make it easier for ''Spartina'' to grow on.

Uses by Humans

Native Americans near the

Jamestown settlement Jamestown Settlement is a living history museum operated by the Commonwealth of Virginia, created in 1957 as Jamestown Festival Park for the 350th anniversary celebration. Today it includes a recreation of the original James Fort (c. 1607 to 1614 ...

manufactured shell beads that were called "rawrenock" in the local

Powhatan language Powhatan or Virginia Algonquian was an Eastern Algonquian subgroup of the Algonquian languages. It was formerly spoken by the Powhatan people of tidewater Virginia. Following 1970s linguistic research by Frank Thomas Siebert, Jr., some of the l ...

. The production process involved grinding broken ribbed mussel shells into disk-shaped beads and drilling a central hole to string the jewelry with. Surviving examples were recovered from the refuse that filled an abandoned well within the James Fort.

References

''Geukensia demissa'' (Dillwyn, 1817)

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organisms. Content The content of the registry is edited and maintained by scientific specialist ...

(2012) * Loren Coen and Keith Walter
Ribbed Mussel ''Geukensia demissa''
South Carolina Department of Natural Resources * http://www.sms.si.edu/irlspec/Geukensia_demissa.htm {{Taxonbar, from=Q5554808 Mytilidae Bivalves described in 1817