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Encyclopedia > Malacologist
Mollusks

Roman snail (Helix pomatia)
Scientific classification
Kingdom: Animalia
Subkingdom: Metazoa
Branch: Bilateria
Superphylum: Protostomia
Phylum: Mollusca
Linnaeus, 1758
Classes

Caudofoveata
Aplacophora
Polyplacophora - Chitons
Monoplacophora
Bivalvia - Bivalves
Scaphopoda - Tusk shells
Gastropoda - Snails and Slugs
Cephalopoda - Squids, Octopuses, etc.
Download high resolution version (750x1020, 40 KB) Gastropod Detail of image from pixelquelle. ... Scientific classification or biological classification is how biologists group and categorize extinct and living species of organisms. ... Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria Placozoa Subregnum Bilateria  Acoelomorpha  Orthonectida  Rhombozoa  Myxozoa  Superphylum Deuterostomia     Chordata (vertebrates, etc. ... Phyla Radiata Cnidaria Ctenophora - Comb jellies Bilateria Protostomia Acoelomorpha Platyhelminthes - Flatworms Nemertina - Ribbon worms Gastrotricha Gnathostomulida - Jawed worms Micrognathozoa Rotifera - Rotifers Acanthocephala Priapulida Kinorhyncha Loricifera Entoprocta Nematoda - Roundworms Nematomorpha - Horsehair worms Cycliophora Mollusca - Mollusks Sipuncula - Peanut worms Annelida - Segmented worms Tardigrada - Water bears Onychophora - Velvet worms Arthropoda - Insects, etc. ... Superphyla Protostomia Deuterostomia The Bilateria is a branch of Metazoa. ... Phyla Mollusca Arthropoda Annelida Protostomes (from the Greek: first the mouth) are a superphylum of animals in the taxonomic group bilateria, and include animals such as arthropods, mollusks, and nematodes. ... A painting of Carolus Linnaeus Carl Linnaeus, also known after his ennoblement as Carl von Linné   listen?, and who wrote under the Latinized name Carolus Linnaeus (May 23, 1707 – January 10, 1778), was a Swedish botanist who laid the foundations for the modern scheme of taxonomy. ... Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ... Caudofoveata is a small class of the phylum mollusca, also known as Chaetodermomorpha. ... Subclasses and families Subclass Chaetodermomorpha (Caudofoveata) Family Chaetodermidae Family Falcidentidae Family Limifossoridae Family Metachaetodermatidae Family Prochaetodermatidae Family Scutopidae Subclass Neomeniomorpha (Solenogastres) Family Acanthomeniidae Family Amphimeniidae Family Dondersiidae Family Drepanomeniidae Family Epimeniidae Family Gymnomeniidae Family Hemimeniidae Family Heteroherpiidae Family Imeroherpiidae Family Lepidomeniidae Family Macellomeniidae Family Meiomeniidae Family Neomeniidae Family Perimeniidae Family... Families See text Chitons, also called polyplacophorans and rarely polyplacophores, are 860 species of molluscs of the Class Polyplacophora. ... Orders Cyrtonellida 1987 Tryblidiida 1987 [Tryblidioidea] Tryblidiida 1982 [Bellerophontida] 1987 Pelagiellida 1987 Monoplacophora is a class of Mollusks thought to be extinct until 1952, when a living animal was dredged up from deep marine sediments. ... Orders Subclass Protobranchia Solemyoida Nuculoida Subclass Pteriomorphia - oysters Arcoida Mytiloida Pterioida Subclass Paleoheterodonta - mussels Trigoinoida Unionoida Subclass Heterodonta - clams, zebra mussels Veneroida Myoida Subclass Anomalosdesmata Pholadomyoida Animals of the Class Bivalvia are known as bivalves because they typically have two-part shells, with both parts being more or less symmetrical. ... Orders Dentaliida Gadilida The tusk shells are a class Scaphopoda of marine mollusks distinguished by curved tubular shells open at both ends, resembling a elephants tusk (thus the name). ... Orders Dentaliida Gadilida The tusk shells are a class Scaphopoda of marine mollusks distinguished by curved tubular shells open at both ends, resembling a elephants tusk (thus the name). ... Subclass Subclass Eogastropoda     Patellogastropoda Subclass Orthogastropoda   Superorder Cocculiniformia   Superorder Hot Vent Taxa     Neomphaolida   Superorder Vetigastropoda   Superorder Neritaemorphi     Neritopsina   Superorder Caenogastropoda     Architaenioglossa     Sorbeoconcha   Superorder Heterobranchia     Heterostropha     Opisthobranchia     Pulmonata The gastropods, or univalves, are the largest and most successful class of mollusks, with 60,000-75,000 species, and second largest class... Giant African Snail (Achatina fulica) The name snail applies to most members of the molluscan class Gastropoda that have coiled shells. ... Slugs are gastropods without shells or with very small shells, in contrast with snails from which they evolved, which have a prominent shell. ... Orders Sepiida Sepiolida Spirulida Teuthida Octopoda Vampyromorphida Nautilida The Cephalopods (head-foot) are the mollusc class Cephalopoda characterized by bilateral body symmetry, a prominent head, and a modification of the mollusc foot into the form of arms or tentacles. ... Suborders Myopsina Oegopsina Squids are the large, diverse group of marine mollusks, popular as food in cuisines as widely separated as the Korean and the Italian. ... Families 14 in two suborders, see text. ...

The mollusks or molluscs are the large and diverse phylum Mollusca, which includes a variety of familiar creatures well-known for their decorative shells or as seafood. These range from tiny snails and clams to the octopus and squid (which are considered the most intelligent invertebrates). The giant squid is the largest invertebrate, and, except for their larvae and some recently captured juveniles, has never been observed alive, although the Colossal Squid is likely to be even larger. Phylum (plural: phyla) is a taxon used in the classification of animals. ... Seafood in Brussels, Belgium Seafood is any sea animal that is served as food or is suitable for eating. ... Giant African Snail (Achatina fulica) The name snail applies to most members of the molluscan class Gastropoda that have coiled shells. ... Maxima clam (Tridacna maxima) Clams are shelled marine or freshwater molluscs belonging to the class Bivalvia. ... Families 14 in two suborders, see text. ... Suborders Myopsina Oegopsina Squids are the large, diverse group of marine mollusks, popular as food in cuisines as widely separated as the Korean and the Italian. ... Invertebrate is a term coined by Jean-Baptiste Lamarck to describe any animal without a spinal column. ... Species Architeuthis dux Architeuthis hartingii Architeuthis japonica Architeuthis kirkii Architeuthis martensi Architeuthis physeteris Architeuthis sanctipauli Architeuthis stockii Giant squid are marine mollusks of the class Cephalopoda, represented by the eight species of the genus Architeuthis. ... Binomial name Mesonychoteuthis hamiltoni (Robson, 1925) The Colossal Squid (Mesonychoteuthis hamiltoni) is the largest known type of squid and the only species in its genus, Mesonychoteuthis. ...


Mollusks are triploblastic protostomes. The principal body cavity is a blood-filled hemocoel, with an actual coelom present but reduced to vestiges around the hearts, gonads, and metanephridia (kidney-like organs). The body is divided into a head, often with eyes or tentacles, a muscular foot and a visceral mass housing the organs. Covering the body is a thick sheet called the mantle, which in most forms secretes a calcareous shell. Triploblastic is a condition of the ovum in which there are three primary germinal layers: the ectoderm, mesoderm, and endoderm. ... Phyla Mollusca Arthropoda Annelida Protostomes (from the Greek: first the mouth) are a superphylum of animals in the taxonomic group bilateria, and include animals such as arthropods, mollusks, and nematodes. ... 1. ... A body cavity is an aspect of a number of basic animal body plans (phyla) that incorporate a central body cavity, known as a coelom. ... The heart and lungs (from an older edition of Grays Anatomy) The heart (Latin cor) is a hollow, muscular organ that pumps blood through the blood vessels by repeated, rhythmic contractions. ... The gonad is the organ that makes gametes. ... Metanephridium (pl. ... A Roman snail (Helix pomatia), one of the mollusks The mantle is an organ found in mollusks. ... The hard, rigid outer calcium cumbonate covering of certain animals is called a shell. ...


Mollusks have a mantle, which is a fold of the outer skin lining the shell, and a muscular foot that is used for motion. Many mollusks have their mantle produce a calcium carbonate external shell and their gill extracts oxygen from the water and disposes waste. All species of the phylum Mollusca have a complete digestive tract that starts from the mouth to the anus. Many have a radula, mostly composed of chitin, in the mouth, which allows then to scrape food from the surface by sliding back and forth. Mollusks also have a coelom, made from cell masses, where all organs are suspended. Unlike the closely related annelids, mollusks lack body segmentation. Calcium carbonate is a chemical compound, with chemical formula CaCO3. ... In aquatic organisms, gills are a respiratory organ for the extraction of oxygen from water and for the excretion of carbon dioxide. ... Radula is the scientific name for the toothed chitinous ribbon in the mouth of gastropods. ... In biology, chitin is one of the main components in the cell walls of fungi, the exoskeletons of insects and other arthropods, and in some other animals. ... A body cavity is an aspect of a number of basic animal body plans (phyla) that incorporate a central body cavity, known as a coelom. ... Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata    Oligochaeta - Earthworms and others    Acanthobdellida    Branchiobdellida    Hirudinea - Leeches Class Myzostomida Class Archiannelida (polyphyletic) Class Echiura *Some authors consider the subclasses under Clitellata to be classes The annelids, collectively called Annelida (from Latin annellus little ring), are a large phylum of animals, comprising...


Development passes through one or two trochophore stages, one of which (the veliger) is unique to the group. These suggest a close relationship between the mollusks and various other protostomes, notably the Annelids. Mollusk fossils are some of the best known and are found from the Cambrian onwards. There are eight living classes and one class, known only from fossils: A trochophore (or trocophore) is a type of larva with several bands of cilia. ... The free-swimming larva of certain marine gastropods. ... Classes and subclasses Class Polychaeta (paraphyletic?) Class Clitellata    Oligochaeta - Earthworms and others    Acanthobdellida    Branchiobdellida    Hirudinea - Leeches Class Myzostomida Class Archiannelida (polyphyletic) Class Echiura *Some authors consider the subclasses under Clitellata to be classes The annelids, collectively called Annelida (from Latin annellus little ring), are a large phylum of animals, comprising... The Cambrian is a major division of the geologic timescale that begins about 542 million years before the present (BP) at the end of the Proterozoic eon and ended about 490 million years BP with the beginning of the Ordovician period. ... Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ...



Caudofoveata is a small class of the phylum mollusca, also known as Chaetodermomorpha. ... Subclasses and families Subclass Chaetodermomorpha (Caudofoveata) Family Chaetodermidae Family Falcidentidae Family Limifossoridae Family Metachaetodermatidae Family Prochaetodermatidae Family Scutopidae Subclass Neomeniomorpha (Solenogastres) Family Acanthomeniidae Family Amphimeniidae Family Dondersiidae Family Drepanomeniidae Family Epimeniidae Family Gymnomeniidae Family Hemimeniidae Family Heteroherpiidae Family Imeroherpiidae Family Lepidomeniidae Family Macellomeniidae Family Meiomeniidae Family Neomeniidae Family Perimeniidae Family... Lined Chiton (Tonicella lineata) Chitons, also called polyplacophorans and rarely polyplacophores, are 860 species of molluscs of the Class Polyplacophora. ... Orders Cyrtonellida 1987 Tryblidiida 1987 [Tryblidioidea] Tryblidiida 1982 [Bellerophontida] 1987 Pelagiellida 1987 Monoplacophora is a class of Mollusks thought to be extinct until 1952, when a living animal was dredged up from deep marine sediments. ... Orders Subclass Protobranchia Solemyoida Nuculoida Subclass Pteriomorphia - oysters Arcoida Mytiloida Pterioida Subclass Paleoheterodonta - mussels Trigoinoida Unionoida Subclass Heterodonta - clams, zebra mussels Veneroida Myoida Subclass Anomalosdesmata Pholadomyoida Animals of the Class Bivalvia are known as bivalves because they typically have two-part shells, with both parts being more or less symmetrical. ... Maxima clam (Tridacna maxima) Clams are shelled marine or freshwater molluscs belonging to the class Bivalvia. ... The name oyster is used for a number of different groups of mollusks which grow for the most part in marine or brackish water. ... Genera See text Scallops are the family Pectinidae of bivalve molluscs. ... Orders A mussel is a bivalve mollusc that can be found in lakes, rivers, creeks, intertidal areas, and throughout the ocean. ... Orders Dentaliida Gadilida The tusk shells are a class Scaphopoda of marine mollusks distinguished by curved tubular shells open at both ends, resembling a elephants tusk (thus the name). ... Subclass Subclass Eogastropoda     Patellogastropoda Subclass Orthogastropoda   Superorder Cocculiniformia   Superorder Hot Vent Taxa     Neomphaolida   Superorder Vetigastropoda   Superorder Neritaemorphi     Neritopsina   Superorder Caenogastropoda     Architaenioglossa     Sorbeoconcha   Superorder Heterobranchia     Heterostropha     Opisthobranchia     Pulmonata The gastropods, or univalves, are the largest and most successful class of mollusks, with 60,000-75,000 species, and second largest class... Giant African Snail (Achatina fulica) The name snail applies to most members of the molluscan class Gastropoda that have coiled shells. ... Slugs are gastropods without shells or with very small shells, in contrast with snails from which they evolved, which have a prominent shell. ... Limpets in their natural habitat (here northwestern Galicia), one animal was seperated from the rock and turned over for the fotograf to have a view of the living inside A limpet (Patella vulgata) is a marine Mollusk of the class Gastropoda. ... Families Superfamily Akeroidea Akeridae Superfamily Aplysioidea Aplysiidae Sea hares (also called sea slugs) are small marine gastropod molluscs of the suborder Anaspidea (P. Fisher, 1883) in the subclass Orthogastropoda, class Gastropoda, phylum Mollusca. ... Families Clionidae Cliopsidae Hermaeidae Hydromylidae Laginiopsidae Notobranchaeidae Pneumodermatidae Thliptodontidae Sea angels are small pteropod mollusks of the suborder Gymnosomata. ... Families Limacinidae Cavoliniidae Clioidae Creseidae Cuvierinidae Praecuvierinidae Peraclididae Cymbuliidae Desmopteridae Sea butterflies, or flapping snails, are holoplanktonic mollusks (Mollusca, Gasteropoda), belonging to the suborder Thecosomata (Blainville, 1824). ... Genera Alliodoris Anisodoris Archidoris Artachaea Austrodoris Doridium Doris Siraius The Sea Lemon is a large (up to 20 cm) flattened oval marine nudibranch without a shell. ... Orders Sepiida Sepiolida Spirulida Teuthida Octopoda Vampyromorphida Nautilida The Cephalopods (head-foot) are the mollusc class Cephalopoda characterized by bilateral body symmetry, a prominent head, and a modification of the mollusc foot into the form of arms or tentacles. ... Suborders Myopsina Oegopsina Squids are the large, diverse group of marine mollusks, popular as food in cuisines as widely separated as the Korean and the Italian. ... Families 14 in two suborders, see text. ... Species Allonautilus perforatus Allonautilus scrobiculatus Nautilus belauensis Nautilus macromphalus Nautilus pompilius pompilius Nautilus pompilius suluensis Nautilus stenomphalus The nautilus is a marine creature of the class Cephalopoda. ... Families Sepiadariidae Sepiidae Cuttlefish are animals of the order Sepiida, and are marine cephalopods, small relatives of squids and nautilus. ... Orders See text The Rostroconchia is a class of extinct mollusks dating from the early Cambrian to the late Permian. ...

                 Caudofoveata (?)
                 Aplacophora
hypothetical                     Polyplacophora
ancestral                Monoplacophora
mollusk                   Gastropoda
                    Cephalopoda
                    Bivalvia
                    Scaphopoda

Brusca & Brusca (1990) suggest that the bivalves and scaphopods are sister groups, as are the gastropods and cephalopods, so indicated in the relationship diagram above.


Malacology is the technical name for the scientific study of mollusks. Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ...


In this Phylum's level of organization, organ systems from all three primary germ layers can be found:

  1. Nervous System (with brain).
  2. Excretory System (nephridium or nephridia).
  3. Circulatory System (open).
  4. Respiratory System (gills or lungs).
  • No skeletal system can be found.

See also

// Aerobiology Anatomy Arachnology Astrobiology Biochemistry Bionics Biogeography Bioinformatics Biomechanics Biophysics Botany Cell biology Chorology Crustaceology Cryptozoology Cycles Cytology Developmental biology E. H. Davidson, Genomic Regulatory Systems: Development and Evolution (Academic Press, San Diego, CA, 2001). ...

References

Wikibooks has a Dichotomous Key related to this taxon:
Mollusca
  • Brusca & Brusca, 1990. Invertebrates, Sinauer Associates, Inc., Sunderland, Mass.
  • Starr & Taggart, 2002. Biology: The Unity and Diversity of Life, Thomson Learning, inc., Pacific Grove, California.

 
 

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