- Conch. Conches are known worldwide for their beautiful shells instead of the snail that may have once lived in them.
- Cowrie. Cowrie shells are the homes for tiny to large sea snails varying from approximately 5mm to 19mm in length.
- Abalone. Abalones are marine gastropods that belong in the family Haliotidae, which contains only one genus, Haliotis.
- Murex. Murex is a medium to large-sized predatory tropical sea snail from the family Muricidae. These marine gastropod mollusks are carnivorous and are commonly called “rock snails.”
- Volutes. Volutes (meaning “scroll” in Latin) are identifiable by distinctively marked spiral shells occupied by a medium-sized sea snail.
- Miter Shells. Mitra is a vast genus of medium to relatively large predatory sea snails that belong to the Mitridae family.
- Drupe Shells. The species found living in Drupe-type shells belong to the family Muricidae and are commonly called rock snails.
- Auger Shells. Auger snails species come from the Terebridae family consisting of more than 400 known species around the world.
- Olive Shells. Olive snails come from a scientific family of marine gastropods called Olividae. ...
Do all gastropods have a shell?
Gastropod shell. Some gastropods appear shell-less ( slugs) but may have a remnant within the mantle, or the shell is reduced such that the body cannot be retracted within ( semi-slug ). Some snails also possess an operculum that seals the opening of the shell, known as the aperture, which provides further protection.
What is the larval shell of a gastropod called?
The larval shell of a gastropod is called a protoconch . The principal characteristic of the Gastropoda is the asymmetry of their principal organs. The essential feature of this asymmetry is that the anus generally lies to one side of the median plane.;
What is the scientific name for gastropods?
In the scientific literature, gastropods were described under "gasteropodes" by Georges Cuvier in 1795. The word "gastropod" derives from the Ancient Greek γαστήρ ("stomach") and πούς ("foot"), a reference to the position of the animals' "feet" below their abdomen.
What are some marine animals in the gastropod class?
Marine animals in the gastropod class include whelks, cowries, abalone, conchs, limpets, sea hares and nudibranchs. Despite their differences, all gastropods do have a couple things in common. All move using a muscular foot.
What gastropod has a shell?
The typical snail has a calcareous shell coiled in a spiral pattern around a central axis called the columella. Generally, the coils, or whorls, added later in life are larger than those added when the snail is young. At the end of the last whorl is the aperture, or opening.
Do all gastropods have shells?
While gastropods have many different shell shapes (or no shells at all) and lifestyles, they are united by undergoing a process called torsion during their development (see below). In some snails, fertilization occurs internally through copulation, but in others it involves external spawning.
What are the 2 gastropods that are shell less?
Gastropods are a highly diverse Class of molluscs that include limpets, whelks, periwinkles, abalones, venomous cone shells, and the shell-less nudibranchs, sea slugs and sea hares.
Why do gastropods have shells?
The gastropod shell is part of the body of a gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium storage.
Do snails have shells?
Young snails have shells that are nearly transparent. The older they get, the thicker their shells become. Glands that are distributed across their body solidify the shell with calcium carbonate. This creates two layers of calcium in the snail shell.
What is a marine gastropod without a shell?
Those gastropods without a shell, and those with only a very reduced or internal shell, are usually known as slugs; those with a shell into which they can partly but not completely withdraw are termed semislugs.
Do bivalves have a shell?
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.
Do all molluscs have shells?
Mollusks usually have a shell (although some do not). Mollusks also have an extension of the body wall called the mantle. This portion of the animal's anatomy is responsible for secreting the shell. The mantle encloses the mantle cavity which contains the Ctenidia (gills), anus and excretory pores.
What is the shell of a gastropod made of?
The gastropod shell has three major layers secreted by the mantle. The calcareous central layer, tracum, is typically made of calcium carbonate precipitated into an organic matrix known as conchiolin. The outermost layer is the periostracum which is resistant to abrasion and provides most shell coloration. The body of the snail contacts the innermost smooth layer that may be composed of mother-of-pearl or shell nacre, a dense horizontally packed form of conchiolin, which is layered upon the periostracum as the snail grows.
What is the shell of a sea snail?
Shells of two different species of sea snail: on the left is the normally sinistral (left-handed) shell of Neptunea angulata, on the right is the normally dextral (right-handed) shell of Neptunea despecta. The shell of a large land snail (probably Helix pomatia) with parts broken off to show the interior structure. 1 – umbilicus.
What are the controlling variables for gastropods?
Controlling variables are: The rate of growth per revolution around the coiling axis. High rates give wide-mouthed forms such as the abalone, low rates give highly coiled forms such as Turritella or some of the Planorbidae.
Why are some gastropods reduced?
The shells of some gastropods have been reduced or partly reduced during their evolution. This reduction can be seen in all slugs, in semi-slugs and in various other marine and non-marine gastropods. Sometimes the reduction of the shell is associated with a predatory way of feeding.
What are the four views of the shell of Arianta arbustorum?
Four views of a shell of Arianta arbustorum: Apertural view (top left), lateral view (top right), apical view (bottom left), and umbilical view (bottom right). The gastropod shell is part of the body of a gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, ...
Which side of the gastropod is the dextral shell?
If a coiled gastropod shell is held with the spire pointing upwards and the aperture more or less facing the observer, a dextral shell will have the aperture on the right-hand side, and a sinistral shell will have the aperture on the left-hand side. This chirality of gastropods is sometimes overlooked when photographs of coiled gastropods are "flipped" by a non-expert prior to being used in a publication. This image "flipping" results in a normal dextral gastropod appearing to be a rare or abnormal sinistral one.
What is the name of the shell that seals the opening of the shell?
Some snails also possess an operculum that seals the opening of the shell, known as the aperture, which provides further protection. The study of mollusc shells is known as conchology. The biological study of gastropods, and other molluscs in general, is malacology. Shell morphology terms vary by species group.
What are the shelled gastropods?
The marine shelled species of gastropods include species such as abalone, conches, periwinkles, whelks, and numerous other sea snails that produce seashells that are coiled in the adult stage—though in some, the coiling may not be very visible, for example in cowries.
Where does the word gastropod come from?
The word gastropod comes from Greek γαστήρ ( gastḗr 'stomach') and πούς ( poús 'foot'), a reference to the fact that the animal's "foot" is positioned below its guts. The earlier name "univalve" means one valve (or shell), in contrast to bivalves, such as clams, which have two valves or shells.
What is the name of the phylum of snails and slugs?
Psilogastropoda - represented as Gastropoda. The gastropods ( / ˈɡæstrəpɒdz / ), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda / ɡæˈstrɒpədə /. This class comprises snails and slugs from saltwater, from freshwater, and from the land.
How many species of gastropods are there in the ocean?
Different estimates for aquatic gastropods (based on different sources) give about 30,000 species of marine gastropods, and about 5,000 species of freshwater and brackish gastropods. Many deep-sea species remain to be discovered, as only 0.0001% of the deep-sea floor has been studied biologically.
Why do gastropods have siphons?
Sometimes the shell has a siphonal canal to accommodate this structure. A siphon enables the animal to draw water into their mantle cavity and over the gill. They use the siphon primarily to "taste" the water to detect prey from a distance. Gastropods with siphons tend to be either predators or scavengers.
How many families of gastropods are there?
The fossil history of this class goes back to the Late Cambrian. As of 2017. [update] , 721 families of gastropods are known, of which 245 are extinct and appear only in the fossil record, while 476 are currently extant with or without a fossil record.
How many species of sea snails are there?
There are many thousands of species of sea snails and slugs, as well as freshwater snails, freshwater limpets, and land snails and slugs . The class Gastropoda contains a vast total of named species, second only to the insects in overall number. The fossil history of this class goes back to the Late Cambrian.
What are marine gastropods?
Introduction to Marine Gastropods. Gastropods are a diverse group of mollusks that comprises over 40,000 species of snails, slugs and their relatives. Some gastropods are responsible for some of the most beautiful sea shells you could find, while some gastropods don't have shells at all. Marine animals in the gastropod class include whelks, ...
What are the different types of marine gastropods?
Marine animals in the gastropod class include whelks, cowries, abalone, conchs, limpets, sea hares and nudibranchs. Despite their differences, all gastropods do have a couple things in common. All move using a muscular foot.
What is the process of a gastropod moving on its foot?
That fleshy thing that it moves about on is the foot. In addition to their means of locomotion, all young gastropods have a larval stage, and in this larval stage they go through something called torsion. During this process, the top of the gastropod's body twists 180 degrees on its foot.
What do whelks eat?
Whelks have beautiful spiraled shells that may grow to over two feet long in some species. These animals are carnivores that feed on crustaceans, mollusks, worms and even other whelks.
What do limpets eat?
Limpets are grazers - they feed on algae that they scrape off the rocks with their radula.
What is the cover of a snail's shell called?
Many gastropods with shells have an operculum, which is a horny cover that, like a trap door, fits to the shell opening and can be closed to retain moisture or protect the snail from predators. There are so many species of gastropods, it would be impossible to include them all here.
What is the shell of a cowry?
Adult cowries have a smooth, thick, glossy shell. The shell in some cowries may be covered by the snail's mantle.
What are the shells of gastropods?
The shells of some species are used as ornaments or in making jewelry. Some gastropods are scavengers, feeding on dead plant or animal matter; others are predators; some are herbivores, feeding on algae or plant material; and a few species are external or internal parasites of other invertebrates.
What are the three groups of gastropods?
Traditionally, the three main gastropod groups are the prosobranchs (subclass Prosobranchia), the opisthobranchs (subclass Opisthobranchia), and the pulmonates (subclass Pulmonata); however, many authorities classify the pulmonates as a subgroup within subclass Opisthobranchia. The prosobranchs generally secrete a substantial shell into which ...
What is the difference between a pulmonate and an opisthobranch?
Opisthobranchs are marine species that often have a reduced or absent shell and very colourful bodies. The pulmonates are snails and slugs that lack an operculum but show complex and highly varied body structures. They have a “lung” or pulmonary cavity that serves also as a water reservoir.
How many gastropods are there in the ocean?
Of the more than 65,000 species, about 30,000 are marine, 5,000 live in fresh water, and 30,000 live on land. In general, oceanic gastropods are most diverse in number of species and in variety of shell structures in tropical waters; several hundred species (each represented by a small number of individuals) can be found in a single coral reef habitat. This is in contrast to the Arctic or subarctic coasts, where the few species present are represented by many individuals. A number of deep-sea species are known, and a significant snail fauna is associated with hydrothermal vents. Most marine species have large ranges.
How big are freshwater snails?
The largest freshwater snails, Pomacea from South America, reach nearly 10 centimetres in diameter, and the largest marine snail, the Australian Syrinx aruanus, occasionally grows to more than 0.6 metre (two feet).
How big are land snails?
At the other extreme, the largest land snail, the African Achatina achatina, forms a shell that is almost 20 centimetres (eight inches) long.
How do snails shape?
Snails show a tremendous variety of shapes, based primarily upon the logarithmic spiral. They can be coiled flatly in one plane, as in Planorbis; become globose with the whorls increasing rapidly in size, as in Pomacea; have the whorls become elongate and rapidly larger, as in Conus and Scaphella; have a few flatly coiled whorls that massively increase in width, as in Haliotis; become elongated and spike-shaped, as in Turritella; or be humped to form a limpet shape, as in Fissurella. Often a number of such shell shapes can be found among species within a single family, but such marine families as the Terebridae, Conidae, and Cypraeidae are conservative in shape. Shells of different species vary markedly in thickness, and those of many species bear conspicuous spines and ridges, probably as an evolutionary adaptation to predation.
What is a gastropod shell?
The gastropod shell is a distinctive and charismatic characteristic of most gastropods . The majority of gastropods possess a shell of some sort and the design of these shells is highly variable. However, in terrestrial slugs it is greatly reduced or absent and in sea slugs it is lost before the animal reaches maturity.
What is the shell of a gastropod made of?
The Structure & Anatomy of the Gastropod Shell. Gastropod shells are comprised of a mixture of calcium carbonate and an organic protein matrix called conchin or conchiolin. The gastropod shell is constructed in three layers. The outer layer is made up of conchiolin and is called the periostracum.
How are the operculum and clausilium similar?
Although the operculum and the clausilium are similar in that they act like doors to seal shut the snail’s home they evolved separately, occur in different families of snails and operate using different mechanisms.
How do snails seal their shells?
They can possess either an operculum or a clausilium, calcareous structures that act like doors, or they can build themselves a dried mucous epiphragm. Any individual species of snail will only use one of these methods to shut up shop. An epiphragm is a disposable door. Any time a snail wishes to rest, and be safer from predators and the weather it can secrete a layer of quick drying muscous from its foot that is stretched across the opening of the shell.
What is the outer layer of a snail made of?
The outer layer is made up of conchiolin and is called the periostracum. This periostracum is typically what gives the shell its colourful pattern. The Anatomy of a Snail Shell. The main strength of the shell comes from the calcium carbonate that makes up the middle layer.
Why do snails coil around the pillar?
Firstly it make the snails home much more compact, meaning it is easier to carry around and more fully protective.
Why do snails have shells coiled in the opposite direction?
This can cause a snail problems because a right-handed snail cannot mate with a left-handed snail. This is a result of the positioning of the genitalia in relationship to the shell coils.
1. Gastropoda
The study of shells or Conchology forms part of a greater science called Malacology, which studies gastropods exclusively. Gastropod shells were once the home of a snail, a type of mollusk.
2. Bivalvia
Bivalves are the most abundant type of shell on the beaches of the world. There are at least 10,000 recorded bivalve species. The name is from the Latin, “bis,” which means “two,” and “valvae,” which means “leaves of a door.”
3. Scaphopoda
Scaphopoda shells are commonly called tusk shells and tooth shells because of their unique shape and are not very common to find on beaches. The name is derived from Ancient Greek, meaning “boat foot” or “shovel foot.”
4. Polyplacophora
The species that belong in the Polyplacophor group are more commonly referred to as “ chitons .” Their shells have eight valves, thus giving them another name, “ the eight-shelled mollusks .”
5. Cephalopoda
Cephalopods are better known as squids or octopuses, and only a few of the Cephalopoda species have shells. However, some do like to make their homes inside of shells. All cephalopod species are invertebrates and share specific characteristics like they all have arms or tentacles, none have backbones and all have blue-colored blood.
Overview
Parts of the shell
The terminology used to describe the shells of gastropods includes:
• Aperture: the opening of the shell
• Lip: peristome: the margin of the aperture
• Apex: the smallest few whorls of the shell
Shell layers
The gastropod shell has three major layers secreted by the mantle. The calcareous central layer, tracum, is typically made of calcium carbonate precipitated into an organic matrix known as conchiolin. The outermost layer is the periostracum which is resistant to abrasion and provides most shell coloration. The body of the snail contacts the innermost smooth layer that may be composed of mother-of-pearl or shell nacre, a dense horizontally packed form of conchiolin, whi…
Morphology
Gastropod shell morphology is usually quite constant among individuals of a species. Controlling variables are:
• The rate of growth per revolution around the coiling axis. High rates give wide-mouthed forms such as the abalone, low rates give highly coiled forms such as Turritella or some of the Planorbidae.
Chirality
Most gastropod shells are spirally coiled. The majority (over 90%) of gastropod species have dextral (right-handed) shells, but a small minority of species and genera are virtually always sinistral (left-handed), and a very few species (for example Amphidromus perversus ) show a mixture of dextral and sinistral individuals. There occur also aberrantly sinistral forms of dextral species and some of these are highly sought by shell collectors.
Standard ways of viewing a shell
• Apertural view of shell of Valvata sincera
• Abapertural view of shell of Valvata sincera
• Umbilical view of shell of Valvata sincera
• This dorsal view of the living animal Calliostoma bairdii also shows an apical view of its shell
Description
The shell begins with the larval shell, the (usually) minute embryonic whorls known as the protoconch, which is often quite distinct from the rest of the shell and has no growth lines. From the protoconch, which forms the apex of the spire, the coils or whorls of the shell gradually increase in size. Normally the whorls are circular or elliptical in section. The spire can be high or low, broad or slender, according to the way the coils of the shell are arranged, and the apical angle of the sh…
Dimensions
The most frequently used measurements of a gastropod shell are: the height of the shell, the width of the shell, the height of the aperture and the width of the aperture. The number of whorls is also often used.
In this context, the height (or the length) of a shell is its maximum measurement along the central axis. The width (or breadth, or diameter) is the maximum measurement of the shell at right angl…
Overview
The gastropods , commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (/ɡæsˈtrɒpədə/).
This class comprises snails and slugs from saltwater, from freshwater, and from the land. There are many thousands of species of sea snails and slugs, as well as freshwater snails, freshwater limpets, and land snails and slugs.
Etymology
In the scientific literature, gastropods were described as "gasteropodes" by Georges Cuvier in 1795. The word gastropod comes from Greek γαστήρ (gastḗr 'stomach') and πούς (poús 'foot'), a reference to the fact that the animal's "foot" is positioned below its guts.
The earlier name "univalve" means one valve (or shell), in contrast to bivalves, such as clams, which have two valves or shells.
Diversity
At all taxonomic levels, gastropods are second only to the insects in terms of their diversity.
Gastropods have the greatest numbers of named mollusc species. However, estimates of the total number of gastropod species vary widely, depending on cited sources. The number of gastropod species can be ascertained from estimates of the number of described species of Mollusca with accepted names: about 85,000 (minimum 50,000, maximum 120,000). But an estimate of the tot…
Habitat
Some of the more familiar and better-known gastropods are terrestrial gastropods (the land snails and slugs). Some live in fresh water, but most named species of gastropods live in a marine environment.
Gastropods have a worldwide distribution, from the near Arctic and Antarctic zones to the tropics. They have become adapted to almost every kind of existence on earth, having colonized nearly e…
Anatomy
Snails are distinguished by an anatomical process known as torsion, where the visceral mass of the animal rotates 180° to one side during development, such that the anus is situated more or less above the head. This process is unrelated to the coiling of the shell, which is a separate phenomenon. Torsion is present in all gastropods, but the opisthobranch gastropods are secondarily untorted to v…
Life cycle
Courtship is a part of the behavior of mating gastropods with some pulmonate families of land snails creating and utilizing love darts, the throwing of which have been identified as a form of sexual selection.
The main aspects of the life cycle of gastropods include:
• Egg laying and the eggs of gastropods
Feeding behavior
The diet of gastropods differs according to the group considered. Marine gastropods include some that are herbivores, detritus feeders, predatory carnivores, scavengers, parasites, and also a few ciliary feeders, in which the radula is reduced or absent. Land-dwelling species can chew up leaves, bark, fruit and decomposing animals while marine species can scrape algae off the …
Genetics
Gastropods exhibit an important degree of variation in mitochondrial gene organization when compared to other animals. Main events of gene rearrangement occurred at the origin of Patellogastropoda and Heterobranchia, whereas fewer changes occurred between the ancestors of Vetigastropoda (only tRNAs D, C and N) and Caenogastropoda (a large single inversion, and translocations of the tRNAs D and N). Within Heterobranchia, gene order seems relatively conser…