A few are carnivorous, eating much larger prey than the tiny micro algae eaten by other bivalves. The best known examples of bivalves are clams, mussels, scallops and oysters. [1] Bivalves have two shells or valves connected by a hinge with hinge teeth.
Full Answer
What are the 4 types of bivalves?
The 5 main types of molluscs
- Gastropods. The gastropods are the largest group of molluscs and can be found in saltwater, freshwater and terrestrial environments.
- Bivalves. Several species of bivalves are common menu items at most seafood restaurants. ...
- Chitons. Chitons are small marine molluscs that can greatly differ in appearance from species to species. ...
- Cephalopods. ...
- Scaphopods. ...
Why are bivalves considered mollusks?
Hypothetical ancestral mollusc
- Mantle and mantle cavity. The mantle cavity, a fold in the mantle, encloses a significant amount of space. ...
- Shell. ...
- Foot. ...
- Circulatory system. ...
- Respiration. ...
- Eating, digestion, and excretion. ...
- Nervous system. ...
What is difference between bivalves and univalves?
is that univalve is a univalve mollusk or its shell while bivalve is any mollusc belonging to the taxonomic class bivalvia, characterized by a shell consisting of two hinged sections, such as a scallop, clam, mussel or oyster. is having one valve, typically used to refer to mollusks, notably slugs and snails.
What are some examples of bivalve fossils?
Some parts on the exterior of modern bivalve shells (clams, mussels, and scallops) with different shapes, which can be preserved in fossils. Examples are Little neck clam (Mercenaria mercenaria), Common mussel ( Mytilus edulis ), and Rough scallop (Aequipecten muscosus).
What are 3 examples of bivalve?
Examples of BivalvesClams are mollusks found in both freshwater and saltwater environments. ... Oysters are a type of saltwater clam, and some varieties produce pearls. ... Mussels, like clams, are mollusks that can live in either freshwater or saltwater. ... Scallops are perhaps best known for their use as food.
What are bivalves give 5 examples?
They include the clams, oysters, cockles, mussels, scallops, and numerous other families that live in saltwater, as well as a number of families that live in freshwater. The majority are filter feeders. The gills have evolved into ctenidia, specialised organs for feeding and breathing.
What are the 4 types of bivalves?
Bivalves include clams, scallops, oysters, and mussels. As their name implies, they have two parts of their shell, which can open and close.
Which animals are bivalves?
Clams, mussels, oysters, and scallops are members to the class Bivalvia (or Pelecypodia). Bivalves have two shells, connected by a flexible ligament, which encase and shield the soft vulnerable parts of the creature.
Is crab a bivalve?
bivalve shellfish such as clams, oysters, scallops, and mussels, other molluscan shellfish such as whelks and, the tomalley of lobster and crab.
Are snails bivalves?
Juliidae, common name the bivalved gastropods, is a family of minute sea snails, marine gastropod mollusks or micromollusks in the superfamily Oxynooidea, an opisthobranch group. These are sacoglossan (sap-sucking) sea snails, and many of them are green in color.
Is sea Urchin a bivalve?
Waldo is a genus of small marine clams in the family Galeommatidae. It includes five species which are all obligate commensals of sea urchins....Waldo (bivalve)WaldoKingdom:AnimaliaPhylum:MolluscaClass:BivalviaOrder:Galeommatida12 more rows
Is a clam a bivalve?
Bivalve mollusks (e.g., clams, oysters, mussels, scallops) have an external covering that is a two-part hinged shell that contains a soft-bodied invertebrate.
How many species of bivalve are there?
The second most diverse group of molluscs behind gastropods, bivalves are one of the most important members of most marine and freshwater ecosystems. In fact, there are well over 10,000 described species of bivalve, found from the deepest depths of the oceans, to the streams in your backyard.
Which of the following is a bivalve?
The correct option is a) clam. Clams are called bivalves as their shell are also divided into two equal parts and connected by two adductor...
What is the common name for Bivalvia?
clamsIntegrated Taxonomic Information System - ReportCommon Name(s):bivalves [English]clams [English]bivalves [French]palourdes [French]bivalve [Portuguese]15 more rows
What is the family of bivalve?
The Superfamily Mactroidea (Mollusca:Bivalvia) in American Waters pp 93–101Cite as. The Family Mesodesmatidae (Mollusca: Bivalvia)
What is a bivalve mollusk?
Bivalve mollusks (e.g., clams, oysters, mussels, scallops) have an external covering that is a two-part hinged shell that contains a soft-bodied invertebrate.
How do bivalves gather food?
As filter feeders, bivalves gather food through their gills. Some bivalves have a pointed, retractable "foot" that protrudes from the shell and digs into the surrounding sediment, effectively enabling the creature to move or burrow. Bivalves even make their own shells.
What are bivalves used for?
The shells of bivalves are used in craftwork , and the manufacture of jewellery and buttons. Bivalves have also been used in the biocontrol of pollution. Bivalves appear in the fossil record first in the early Cambrian more than 500 million years ago. The total number of known living species is about 9,200.
How many species are there in marine bivalves?
Marine bivalves (including brackish water and estuarine species) represent about 8,000 species, combined in four subclasses and 99 families with 1,100 genera. The largest recent marine families are the Veneridae, with more than 680 species and the Tellinidae and Lucinidae, each with over 500 species. The freshwater bivalves include seven families, ...
How big is a bivalves shell?
Adult shell sizes of bivalves vary from fractions of a millimetre to over a metre in length, but the majority of species do not exceed 10 cm (4 in).
What is the etymology of bivalvia?
The taxonomic term Bivalvia was first used by Linnaeus in the 10th edition of his Systema Naturae in 1758 to refer to animals having shells composed of two valves. More recently, the class was known as Pelecypoda, meaning " axe -foot" (based on the shape of the foot of the animal when extended).
What is the name of the clam that has an empty shell?
Empty shell of the giant clam. ( Tridacna gigas) Empty shells of the sword razor. ( Ensis ensis) Bivalvia ( / baɪˈvælviə / ), 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.
Where are the sensory organs of bivalves located?
The sensory organs of bivalves are not well developed and are largely located on the posterior mantle margins. The organs are usually mechanoreceptors or chemoreceptors, in some cases located on short tentacles. The chemoreceptor cells taste the water and are sensitive to touch. They are typically found near the siphons, but in some species, they fringe the entire mantle cavity. The osphradium is a patch of sensory cells located below the posterior adductor muscle that may serve to taste the water or measure its turbidity, but is probably not homologous with the structure of the same name found in snails and slugs. Statocysts within the organism help the bivalve to sense and correct its orientation. Each statocyst consists of a small sac lined with sensory cilia that detect the movement of a mineral mass, a statolith, under gravity. In the order Anomalodesmata, the inhalant siphon is surrounded by vibration-sensitive tentacles for detecting prey.
How long do clams live?
For example, the soft-shell clam ( Mya arenaria) was thought to be short-lived, but has now been shown to have a lifespan of at least 28 years. The two valves of the bivalve shell are held together at the hinge by a ligament composed of two keratinised proteins, tensilium and resilium.
What are some examples of bivalves?
A few are carnivorous, eating much larger prey than the tiny micro algae eaten by other bivalves. The best known examples of bivalves are clams, mussels, scallops and oysters.
What are bivalves made of?
Shell. Bivalves have two shells or valves connected by a hinge with hinge teeth. They are made of a calcareous mineral, calcite or aragonite. The valves are covered by a periostracum, which is an organic horny substance. This forms the familiar coloured layer on the shell.
What part of the mantle does a bivalve have?
A bivalve takes in water that has plankton and other things floating in it. Some (but not all) molluscs have a part of their mantle known as the siphon (a tube). Siphons, if they exist, come in pairs, one to suck in, one to expel.
What is the largest clam in the world?
Empty shell of the giant clam. ( Tridacna gigas) The world's largest clam (187 cms), a Sphenoceramus steenstrupi fossil from Greenland in the Geological Museum in Copenhagen. The bivalves are a large class of molluscs, also known as pelecypods . They have a hard calcareous shell made of two parts or 'valves'.
How many species of bivalves are there?
There are over 30,000 species of bivalves, including the fossil species. There are about 9,200 living species in 1,260 genera and 106 families. All of them live in the water, most of them in the sea or in brackish water. Some live in fresh water. All are filter feeders: they lost their radula in the course of evolution.
Where are the valves on a brachiopod?
In brachiopods, the two valves are on the dorsal and ventral surfaces of the body, while in bivalves, they are on the left and right sides. Bivalves appeared late in the Cambrian explosion and came to increase in the Palaeozoic, and dominate over brachiopods during the Mesozoic.
Where is food digested in a bivalve?
The food is moved down to the mouth, which is on the other side of the siphon. Food is digested in the bivalve's stomach and intestine, and everything that is not digested goes out through the other siphon, with water. The siphons are an adaptation of burrowing molluscs.
What is a bivalve?
Bivalve, (class Bivalvia), any of more than 15,000 species of clams, oysters, mussels, scallops, and other members of the phylum Mollusca characterized by a shell that is divided from front to back into left and right valves.
How big are bivalves?
Bivalves range in size from about one millimetre (0.04 inch) in length to the giant clam of South Pacific coral reefs, Tridacna gigas, which may be more than 137 centimetres (54 inches) in length and weigh 264 kilograms (582 pounds). Such an animal may have a life span of about 40 years.
What is a byssus?
The byssus is a larval feature that is retained by adults of some bivalve groups , such as the true mussels (family Mytilidae) of marine and estuarine shores and the family Dreissenidae of fresh and estuarine waters. Such a shell form and habit evolved first within sediments (endobyssate), where the byssus serves for anchorage ...
What are the most efficient burrowers?
The shells of the most efficient burrowers, the razor clams Ensis and Solen , are laterally compressed, smooth, and elongated. Surface-burrowing species may have an external shell sculpture of radial ribs and concentric lines, with projections that strengthen the shell against predators and damage.
Where do bivalves live?
In shallow seas, bivalves are often dominant on rocky and sandy coasts and are also important in offshore sediments. They occur at abyssal and hadal depths, either burrowing or surface-dwelling, and are important elements of the midoceanic rift fauna.
What are the features of a clam's foot?
In other species, such as the clams, the foot has become modified for rapid and effective digging, and the folds of the mantle tissue have developed into long siphons. Both these features allow the animals to burrow deeply within sand, mud, and other substrates (even into wood and rock).
How long do shells live?
Such an animal may have a life span of about 40 years. The shell morphology and hinge structure are used in classification. In most surface-burrowing species (the hypothetical ancestral habit) the shells are small, spherical or oval, with equal left and right valves.
What is a bivalve?
She serves as the executive director of the Blue Ocean Society for Marine Conservation. A bivalve is an animal that has two hinged shells, which are called valves.
What are bivalve shells?
A bivalve is an animal that has two hinged shells, which are called valves. All bivalves are mollusks. Examples of bivalves are clams, mussels, oysters, and scallops. Bivalves are found in both freshwater and marine environments.
What is the commercial value of bivalve harvests in 2011?
According to NOAA, the commercial value of bivalve harvests in 2011 was over $1 billion, just in the U.S. This harvest weighed over 153 million pounds. Bivalves are organisms particularly vulnerable to climate change and ocean acidification.
How much does a bivalves harvest weigh?
This harvest weighed over 153 million pounds. Bivalves are organisms particularly vulnerable to climate change and ocean acidification. Increasing acidity in the ocean is affecting the ability for bivalves to effectively build their calcium carbonate shells.
How do bivalves feed?
Many bivalves feed by filter feeding, in which they draw water over their gills, and tiny organisms collect in the organism's gill mucus. The also breathe by drawing fresh oxygen from the water as it passes over their gills. When you eat a shelled bivalve, you're eating the body or a muscle inside.
What is the muscle inside a scallop?
When you eat a shelled bivalve, you're eating the body or a muscle inside. When you're eating a scallop, for example, you're eating the adductor muscle. The adductor muscle is a round, meaty muscle that the scallop uses to open and close its shell.
How big is a bivalve?
This species has a shell that is less than a millimeter in size. The largest bivalve is the giant clam. The valves of the clam may be over 4 feet long, and the clam itself may weigh over 500 pounds.
What was the oldest predator in the Devonian era?
The oldest, largest, and fiercest predator of the Devonian “Age of Fishes” in these waters wasDunkleosteus terrelli, a fish capable of biting huge prehistoric sharks in half.
What is the name of the fossil that was discovered in the Cambrian era?
In 1979, Simon Conway Morris discovered an anatomical structure on the fossils called a proto-notochord that would develop into the first true chordates, better known as vertebrates or creatures with spines. However Morris’s suggestion that Pikaia itself was a chordate led to the widely held but incorrect belief that it is the ancestor of all vertebrates, including humans. This caused a huge controversy.
Overview
Anatomy
Bivalves have bilaterally symmetrical and laterally flattened bodies, with a blade-shaped foot, vestigial head and no radula. At the dorsal or back region of the shell is the hinge point or line, which contain the umbo and beak and the lower, curved margin is the ventral or back region. The anterior or front of the shell is where the byssus (when present) and foot are located, and the posterior of the shell is where the siphons are located. With the hinge uppermost and with the a…
Etymology
The taxonomic term Bivalvia was first used by Linnaeus in the 10th edition of his Systema Naturae in 1758 to refer to animals having shells composed of two valves. More recently, the class was known as Pelecypoda, meaning "axe-foot" (based on the shape of the foot of the animal when extended).
The name "bivalve" is derived from the Latin bis, meaning "two", and valvae, meaning "leaves of a …
Comparison with brachiopods
Brachiopods are shelled marine organisms that superficially resembled bivalves in that they are of similar size and have a hinged shell in two parts. However, brachiopods evolved from a very different ancestral line, and the resemblance to bivalves only arose because they occupy similar ecological niches. The differences between the two groups are due to their separate ancestral origins. Different initial structures have been adapted to solve the same problems, a case of con…
Evolutionary history
The Cambrian explosion took place around 540 to 520 million years ago (Mya). In this geologically brief period, all the major animal phyla diverged and these included the first creatures with mineralized skeletons. Brachiopods and bivalves made their appearance at this time, and left their fossilized remains behind in the rocks.
Possible early bivalves include Pojetaia and Fordilla; these probably lie in the stem rather than cro…
Diversity of extant bivalves
The adult maximum size of living species of bivalve ranges from 0.52 mm (0.02 in) in Condylonucula maya, a nut clam, to a length of 1,532 millimetres (60.3 in) in Kuphus polythalamia, an elongated, burrowing shipworm. However, the species generally regarded as the largest living bivalve is the giant clam Tridacna gigas, which can grow to a length of 1,200 mm (47 in) and a weight of more than 200 kg (441 lb). The largest known extinct bivalve is a species of Platyceram…
Distribution
The bivalves are a highly successful class of invertebrates found in aquatic habitats throughout the world. Most are infaunal and live buried in sediment on the seabed, or in the sediment in freshwater habitats. A large number of bivalve species are found in the intertidal and sublittoral zones of the oceans. A sandy sea beach may superficially appear to be devoid of life, but often a very large number of bivalves and other invertebrates are living beneath the surface of the sand. …
Behaviour
Most bivalves adopt a sedentary or even sessile lifestyle, often spending their whole lives in the area in which they first settled as juveniles. The majority of bivalves are infaunal, living under the seabed, buried in soft substrates such as sand, silt, mud, gravel, or coral fragments. Many of these live in the intertidal zone where the sediment remains damp even when the tide is out. When buried in the sediment, burrowing bivalves are protected from the pounding of waves, desiccatio…
Shell
Food
- A bivalve takes in water that has planktonand other things floating in it. Some (but not all) molluscs have a part of their mantle known as the siphon(a tube). Siphons, if they exist, come in pairs, one to suck in, one to expel. Anything that is small enough to fit inside the hole of its incurrent siphon enters the bivalve. When the floating material comes in, it gets stuck in slimy m…
Movement
- Digging
As a group, the bivalves are adapted to penetrate into, and to move along horizontally along, soft ground such as mud and sand. Common examples of this are razor shells, which can dig themselves into the sand with great speed to escape enemies, and cockles. - Swimming
Scallops and file clams can swim to escape a predator, clapping their valves together to create a jet of water. Cockles can use their foot to leap from danger. However these methods quickly exhaust the animal. In the razor shells the siphons can break off only to grow back later.
Defensive Secretions
- The file shells can produce a noxious secretion when threatened, and the fan shells of the same family have a unique, acid-producing organ.
Comparison with Brachiopods
- Bivalves are superficially similar to brachiopods, but the construction of the shell is completely different in the two groups. In brachiopods, the two valves are on the dorsal and ventral surfaces of the body, while in bivalves, they are on the left and right sides. Bivalves appeared late in the Cambrian explosion and came to increase in the Palaeozoic, and dominate over brachiopods du…