The body of molluscs is unsegmented with a distinct head, muscular foot and visceral hump. Phylum mollusca is a very diverse 85,000 species group of mostly marine species. Members of the phylum mollusca are softbodied animals, such as the snail, clam, squid, oyster, and octopus. Also rivals arthropods in terms of ecological success. The classes are gastropoda, monoplacophores, polyplacophores, scaphopods, bivalves, and cephalopods. The phylum mollusca is made up of a large group of species that all share certain characteristics. Consisting of more than 85,000 extant species, mollusca is the second biggest phylum in the animal kingdom, second to only arthropods. Phylum mollusca has been classified differently by different authors depending upon the characters of foot, mantle, shell, muscles, radula, nervous system and respiratory organs. Phylum mollusca its classes characteristics features.
Phylum mollusca phylum annelida phylum arthropoda phylum echinodermata phylum chordata references phylum mollusca snails, slugs, octopi, squids 110,000 species are known. Phylum mollusca objective type questions pdf download. A study of the type series of nautilus pompilius linnaeus, 1758 mollusca, cephalopoda, nautilida svetlana v. Mollusca is one of the most diverse groups of animals on the planet, with at least 50,000 living species and more likely around 200,000. Introduction to mollusca and the class gastropoda freshwater. Many organisms belonging to this phylum have a calciferous shell. Classification of mollusca april, 97 1 victor millard a classification of the living mollusca which was compiled by kay cunningham vaught and published by american malacologists, inc melbourne, florida 32902, usa in 1989 was used as the basis for this compilation.
Ten total classes of molluscs have existed throughout evolutionary history, but only eight of these classes exist today. Soft bodied triploblastic, bilaterally symmetrical, unsegmented schizocoelomates are molluscs true coelomate unsegmented soft bodied animalsmollusca study of mollusca malacology second largest phylum mollusca study of molluscan shells choncology jhonson created the name mollusca for cephalopods and barnacles. Molluscs are soft bodied animals, often with hard shells for protection. The first two classes are thought to represent primitive molluscs, the last three classes include the great bulk of living species. Mollusca is the secondlargest phylum of invertebrate animals after the arthropoda. Many species can actively change their skin color or naturally blend into their surroundings. All animals of the phylum mollusca have bilateral symmetry. Phylum mollusca article about phylum mollusca by the free. Study 22 terms phylum mollusca 5 classes flashcards.
Phylum mollusca the mollusca include chitons, clams, oysters, snails, slugs, squids, nautilus and octopuses. Gastropods comprise approximately 70,000 described liv ing species of marine, terrestrial, and freshwater snails and slugs. Freshwater molluscs are classified into gastropods snails and freshwater limpets and several groups of. The phylum mollusca demonstrate incredible diversity from the clam to the giant squid. It includes such familiar organisms as snails, octopuses, squid, clams, scallops, oysters, and chitons. The bodies are generally very soft and are covered by the hard exoskeleton. All six classes have some external and internal characteristics that are very similar. The first class includes the gastropods, a group of land snails and slugs. An outline for the classification of phylum mollusca in taxonomic. The phylum mollusca has about 100,000 described species and potentially 100,000 species yet to be described strong et al. Molluscs comprise the familiar animals commonly known for both their shells and fine seafood, including snails, clams, octopus and squid. Many, however, occur in fresh water and some even in damp soil.
Download objective type questions of phylum mollusca pdf visit our pdf store. Some also serve as intermediate hosts for parasitic trematodes, and. The girdle is very heavy and extends beyond the lateral margins of the plates. Name a phylum from a previous lab whose members filter feed. European register of marine species and later the world register of marine species. The mollusca is well represented in freshwaters by two classes of molluscs or mollusks, depending on. Enjoy it and then you would even be able to score well in an exam.
They are the largest marine phylum, comprising about 23% of all marine organisms. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Molluscs form the second largest invertebrate group with over 50000 living species and 35000 known. The picture shows muscular foot,visceral mass and the mantle. Molluscs are a diverse animal phylum with a formidable fossil record. Molluscs are found in nearly all freshwater and marine. The second class encompasses the bivalves, a group of oysters, clams, and other organisms with two shells. Mollusca is the second largest phylum of invertebrate animals. Body structure of phylum mollusca, class xi, biology. The mollusca is well represented in freshwaters by two. The phylum mollusca is divided into seven distinct extant classes, three of which gastropoda, bivalvia, and cephalopoda are of major significance in terms both of species numbers and of ecological bioenergetics, and one extinct class.
Around 85,000 extant species of molluscs are recognized. The group is extremely diverse and includes such well known forms as the squid, octopus, slugs, snails and oysters. Members of this phylum have soft, unsegmentated bodies usually enclosed. The phylum mollusca is divided into the following seven classes. There is usually a shell, secreted by a series of tissues called the mantle, and beneath this there is the body, which contains a space mantle cavity in which lie the gills. The phylum mollusca is the secondlargest animal phylum, with over 100,000 species. Classification can be great fun and not as utterly boring as it sometimes turns out to be.
Pdf origin and the early evolution of the phylum mollusca. Mollusks have a dramatic variety of form, ranging from large predatory squids and octopus, some of which show a high degree of intelligence, to grazing forms with elaborately sculpted and colored shells. Monoplacophora, polyplacophora, aplacophora, scaphopoda, gastropoda, bivalvia, cephalopoda. The naming of molluscan classes and their acceptation as monophyletic units. The most distinctive characteristic of chitons is their eightpiece shell. The freshwater gastropoda of the nearctic is divided into two major. Cephalopod molluscs such as squid, cuttlefish and octopus are. The molluscs are the second largest phylum abundance of species next. General characteristics it is the second largest phylum of invertebrates consisting of more than 80,000 living species and about 35,000 fossil species. The references in that work have not been transferred to this one. Some grownups cant see magic ponies but children can explanation. The type of symmetry that mollusks have is bilateral symmetry. Phylum mollusca the word mollusca is derived from the latin word mollis which means soft bodied. Each mollusk has a muscular organ called a foot that is used for gripping or creeping over surfaces.
Many molluscs also live in fresh water and terrestrial environments. Look inside the bodies of various marine animals molluscs. Structure soft bodied animals name from latin word mollus meaning soft most are protected by a hard shell made of calcium carbonate have a reduced internal cell or have lost the shell completely during evolution. The phylum mollusca is one of the three major invertebrate phyla which have successfully evolved on land as well as in the sea, its members are found all over the world in lowlands, forests, deserts, lakes, rivers and oceans.
Mnemonic classes and subclasses of phylum mollusca in. Cephalopod molluscs such as squid, cuttlefish and octopus are among the most neurologically advanced invertebrates. The mantle is a layer of tissue that covers the visceral mass and in many molluscs it contains glands which secrete a hard shell. Firstever observations of a live giant squid in the wild pdf. Phylum mollusca mcq multiple choice question and answer phylum mollusca mcq with detailed explanation for interview, entrance and competitive exams. The word mollusc was derived from the modern latin term mollusca which meant thin. Each of these eight plates is quite similar, except for the first and last. The phylum mollusca is the second largest in the animal kingdom including about 100,000 living species and with a long fossil record of some 35,000 more. The molluscs include many familiar animals, including clams, snails, slugs, and squid, as well as some less familiar animals, like tusk shells and chitons fig. Its fun if you can understand the need for it and how its done. Jul 27, 2017 look inside the bodies of various marine animals molluscs.
They can be found in terrestrial regions as well as in the depths of the seas. Live in a vast range of habitats both aquatic and terrestrial. The adults are triploblastic, bilaterally symmetrical animals with a soft unsegmented body. List four adaptations that class cephalopoda has for hunting. The phylum mollusca is divided into five main classes. The gastropods snails and slugs include by far the most classified species, accounting for 80% of the total. Pdf the paper gives an overview of the modern hypotheses on the origin of the phylum. Mollusca molluscs a very diverse phylum of invertebrates which have a common body plan modified in various ways. Study 22 terms phylum mollusca 5 classes flashcards quizlet. The phylum mollusca consists of over 100,000 marine, freshwater, and terrestrial species. Some also serve as intermediate hosts for parasitic trematodes, and others e.