Phylum Mollusca Classification Mollusca (mollusks) are classified into 6 classes according to their symmetry and the characters of food, shell, mantle, gills, nervous system, muscles, and radula. Gills are also excretory in function. Deuterostomes (like the echinoderms) 2. It inhabits ponds, paddy fields, sometimes streams and rivers It is chiefly hetmvorous and feeds on aquatic plants like Pistia and Valusnena. The body of molluscs is un-segmented with a distinct head, muscular foot and visceral hump. South Africa has recorded 347 sponge species, comprising around 4% of sponge diversity worldwide. The head comprises of tentacles and compound eyes. Spaces amongst the viscera (soft organs) contain blood and form haemocoel. • They are one of the most diverse phyla, second only to Arthropods (insects, crabs, shrimp, and others). to the class Demospongiae. Like Sepia, it is also found in the warm seas. Class 3. It is found in rivers, lakes and ponds. monas- one, plax- plate, pherein- bearing): The shell is spoon or cup shaped. LxAigo is edible. It is divided among seven classes (Ruppert et al., 2004) and is present on nearly every con-tinent. The number of fossil species is estimated between 60,000 and 100,000 additional species. The body is divided into segments. Amphineura: It is a small class of marine molluscs dating back from the Cambrian period. However, local taxonomic knowledge of this phylum is largely incomplete. :��K&�&�#�?�b��+��惼J��8-+s����Ƀ���/Im!����P-��Eۢ��0��. 3. This website includes study notes, research papers, essays, articles and other allied information submitted by visitors like YOU. It is restricted to pericardial cavity (space around the fieart), and to small spaces within kidneys and gonads (testes and ovaries). Chiton is marine and found attached to rocks by its foot the shell consists of a row of eight plates. It is made up of calcium carbonate. The nervous system comprises paired cerebral, pleural, pedal and visceral ganglia joined by the nerve connectives and conumssures. Metameric segmentation and presence of the trochophore larva in both annelids and molluscs suggest that molluscs have descended from the annelids. cuttlefish. Thus it is adapted for both aquatic and terrestrial life. Class Calcarea • Molluscs are soft bodied animals, often with hard shells for protection. The animal is omnivorous feeding on microscopic organisms. Class 2. Its larva lives as parasite on fish. Disclaimer: ITIS taxonomy is based on the latest scientific consensus available, and is provided as a general reference source for interested parties. Content Guidelines 2. Among the molluscs, cuttle fish are exceptional in having closed blood vascular system. Porifera Cnidaria Platyhelminthes Nematoda Mollusca AnnelidaAnnelida Arhropoda Echinodermata ChordataChordata ... •Spiral cleavage •Deuterostome •Mouth forms 2nd •Radial cleavage Hollow Dorsal Nerve Cord Phylum Chordata 1. Sep 23, 2019; 2 min read; Respiration In Mollusca Pdf Download The … Asexual reproduction is absent. The v… When the animal is attacked ink-like fluid is ejected through the funnel to form a smoke cloud. Class 5. A “living fossil” named Neopilina discovered in 1952 from the Pacific Ocean, shows metameric segmentation which is not a characteristic of molluscs. scapha- boat, podos-foot): Class 4. endstream endobj 45 0 obj <> endobj 46 0 obj <> endobj 47 0 obj <>stream One of the arms of male is spoon shaped and is called hectocotylized which is used to transfer sperms into the female. 52 0 obj <>/Filter/FlateDecode/ID[<872E2FCD5300F8449209B98516DCCF31>]/Index[44 21]/Info 43 0 R/Length 60/Prev 25964/Root 45 0 R/Size 65/Type/XRef/W[1 2 1]>>stream It is a marine mollusc. Head is without eyes and tentacles. Phylum - Mollusca MCQ with detailed explanation for interview, entrance and competitive exams. Class 1. Cephalopods are regarded at the top of invertebrates evolution in terms of learned behaviour they exihibit. Molluscs can be divided into ive principal classes, namely Gastropoda, Bivalvia, Scaphopoda, Polyplacophora and Cephalopoda. Biology 18 Spring, 2008 1 Lab 5: Phylum Mollusca Objectives: Understand the taxonomic relationships and major features of mollusks Learn the external and internal anatomy of the clam and squid Understand the major advantages and limitations of the exoskeletons of mollusks in relation to the hydrostatic skeletons of worms and the endoskeletons of Freshwater molluscs are classified into gastropods (snails and freshwater “limpets”) and several groups of Numerous molluscs also live in freshwater and terrestrial habitats. Monoplacophora (Gk. Excretory organs are one or two pairs of sac- like kidneys. Example: Neopilina. Shell consists of single piece or valve. Shell is secreted by mantle. It is also marine. Octopus ejects an inky fluid in water and forms a screen for defence from its enemies. Phylum Mollusca Classes: Gastropoda, Bivalvia, Cephalopoda. It also has internal shell invertebrate is giant squid (Architeuthis) up to 18 meters long. Aplysia, a marine mollusc is commonly known as. amphi- both + two neuron = nerve): There is a present non-ganglionated nerve ring around mouth with two pairs of interconnected nerve cord. Class Aplacophora includes worm-like animals with no shell and a rudimentary body structure. Mollusca. What is the reserve food material in red algae? Some cephalopods are the largest invertebrates. Animals: Phylum Mollusca; Ziser Lecture Notes, 2015.10 Class: Monoplacophora means: “one plate” 25 species small; 3mm to 3 cm fossils known from Cambrian àwas believed to be an extinct group until discovered near Costa Rica in 1952 small, single, low rounded shell with ventral creeping foot superficially resemble limpets (gastropods) Very few are terrestrial found in damp soil. TOS4. Connectives con­nect dissimilar ganglia; however, commissures connect similar ganglia. It also ejects a dark ink to form a smoke cloud to escape from .the enemy. Phylum Mollusca is a very diverse (85,000 species) group of mostly marine species. 64 0 obj <>stream It includes the largest number of molluscs e.g., Pila, Umax, Cypraea (Cowrie), Helix (garden snail), Aplysia (sea hare), Doris (sea lemon), Limnaea, (pond snail), Planorbis, Patella (true limpet), Turbinella (Shankh), Creseis (Sea butterfly). Three major classes make up the phylum Mollusca. Mollusks – Block 1 Nabinger Purpose This lesson is intended to introduce the phylum Mollusca and to go over its general physical characteristics. Classification of Phylum Mollusca. Eight Vertebrate Classes 5. It acts as scavenger and keeps water clean. Phylum Mollusca is the second largest animal phylum. It includes such familiar organisms as snails, octopuses, squid, clams, scallops, oysters, and chitons. ��Y����m��a�:�*���C\;��έv���l{6M׺�;��u��[�]���jPa���۩UŦ�f���r�dv��U�c1�d�b��2 ��F��CT��L��2ݘ�d? The lines of growth indicate the age of the individual. 44 0 obj <> endobj Phylum Mollusca has been divided into following six classes on the basis of foot, shell and mantle. Class Gastropoda Subclass Vetigastropoda It includes dorsal heart, arteries that open into sinuses; (spaces) and veins. hޤ�mo�0���}l51�$q�TU�2Z����NB|H���B�W+�~wv�[���}�v_� �� ����"B����}T�!���J�� E��H/ 6. Pelecypoda or Bivalvia. These are gills (cteoidia). When the development is indirect it includes a characteristic larva, liger, trochophore or glochidium. It leads an amohibious life respiring by means of gill in water and by a pulmonary sac an and. The second class encompasses the bivalves, a group of oysters, clams, and other organisms with two shells. Name the 6 classes in the phylum Mollusca. Shell may be external (e.g., most of molluscs), internal (e.g., slug, cuttle fish, squid) or absent (e.g., Octopus). Classification The phylum Porifera has four classes, namely the Calcarea, Demospongiae, Hexactinellida and Homoscleromorpha. The shell is internal. Mussels, clams, scallops and oysters are examples of bivalves, which have two shells (valves) covering the left and right sides of the body. The body is covered by a shell made up of calcium carbonate. A whitish elevation in each valve is called umbo. The organisms belonging to phylum Mollusca exhibit the following characteristics: 1. Before sharing your knowledge on this site, please read the following pages: 1. The slug is a plant pest. They are marine. They are bilaterally symmetrical, triploblastic and coelomate animal. The shell is univalve and almost always coiled. The proportion of undescribed species is very high. (iii) Better developed sense organs such as eyes, statocysts and osphradia. black mussel. Muscles are un-striped and occur in bundles. • Example : Neopilina . Mollusks may be primitively segmented, but all but the monoplacophorans characteristically lack segmentation and have bodies that are to some degree spirally twisted (e.g. What are the different sources of air pollution? Its body resembles that of Sepia in form except that it is narrower than that of Sepia. Scaphopoda (Gk. It kills its prey with poisonous saliva. Disclaimer Copyright, Share Your Knowledge Pila has osphradium which is meant for testing chemical and physical nature of water. Octopus can change its colour. The shell is slightly curved, tubular and opens at both the ends. (With Methods)| Industrial Microbiology, How is Cheese Made Step by Step: Principles, Production and Process, Enzyme Production and Purification: Extraction & Separation Methods | Industrial Microbiology, Fermentation of Olives: Process, Control, Problems, Abnormalities and Developments, The best answers are voted up and rise to the top. Many, however, occur in fresh water and some even in damp soil. In male the left arm is spoon shaped and is called hectocotylized which is used to transfer sperms into the female. %%EOF In many molluscs, eyes are present over stalks called ommatophores. They are mostly marine. The buccal cavity of Pila contains a rasping organ, the radula, with transverse rows of teeth for cutting the grasses. It is terrestrial and is abundantly found in gardens, cultivated lands and over damp soil. They are mostly found in marine and fresh water. Phylum Mollusca Class Bivalvia Oysters, Clams, Scallops-Oh My! • There are 8 known living classes of molluscs and new species are constantly being discovered. It is a marine and a good swimmer. A foot is located on head . 7. Introduction Bivalves are aquatic mollusks (Phylum Mollusca) that belong to the Class Pelecypoda (or Bivalvia), meaning "hatchet-foot." Species representing each of these classes are included in this guide. What are the three important components of biodiversity? 7. (ii) Mantle may be surrounded by shell, and. What are the general characters of bryophytes? Foot is flat and ventral. Plate 111 = Phylum: Mollusca, Class: Pelecypoda -- Shells of various genera ----- The Class Gastropoda, meaning, "stomach-foot", includes the snails and slugs. Only the gastropods have entered the terrestrial habitat, and some families of snails and mussels are commensalistic. 15 Interesting Forms of Molluscs | Phylum Mollusca, Difference between Insect and Spider | Animal Kingdom. Mollusca is the largest marine phylum, comprising about 23% of all the named marine organisms. The mouth or aperture of the shell is closed by a flat and oval plate, the operculum. Ammonia is chief excretory matter. 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. • Head bears tentacles . 2. pelekus- hatchet Podos foot): Unio, Mytilus (Sea mussel), Teredo SpwoS EnZ (razor shell or razor clam), Solen (razor fish or razor shell), Ostrea (edible oyster), Pecten (scallop), Pinctada (Pearl oyster). The shell is absent. 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). Share Your Word File Why does plant cell possess large sized vacuole? They have die characters of both the phylum Annelida and phylum Mollusca. Plate 108 = Phylum: Mollusca, Class: Pelecypoda -- Sculpturing on shell surfaces. Neopilina is a segmented mollusc. D notochord extends upto cephalic region . h�bbd``b`��@�� H�l ��@�0 ��H����4�?�o ڌ� Classification of Phylum Mollusca: Phylum Mollusca are divided into six classes. Mantle and pulmonary sae (in semi-terrestrial form). Coelom is greatly reduced. The development is either direct or indirect (metamorphosis). sea hare. Share Your PDF File Sepia ink obtained from this animal is used by artists. Yeast: Origin, Reproduction, Life Cycle and Growth Requirements | Industrial Microbiology, How is Bread Made Step by Step? chitons, clams, snails, slugs, octopi, cuttlefish, squid, & nautili second largest phylum (50,000+ species) well known fossil record marine, fresh water, and terrestrial General Characteristics mostly bilateral symmetry unsegmented. kephale- head, podos- foot): Head and foot region combined and modified into a structure which has eyes and eight tentacles, hence the name cephalopod or ‘head foot’. They have die characters of both the phylum Annelida and phylum Mollusca. h�b```f``R``b``�e�e@ ^�3�A�}����_�����6�eN�C�0�00�i6 f��1�0�*k`xjpZhHD�����. Pelecypoda or Lamellibranchiate or Bivalvia (Gk. PDF | On Jan 1, 2016, Richard C. Brusca and others published Phylum Mollusca | Find, read and cite all the research you need on ResearchGate Osphradium is present in some molluscs for testing chemical and physical nature of water. Cephalopoda (Gk. Class: Monoplacophora. Monoplacophora (Gk. It is a hermaphrodite animal. There are present two siphons posteriorly. 5. The key difference between Mollusca and Echinodermata relies on the habitat of the organisms belonging to these two classes.Molluscs live in both terrestrial and aquatic environments while echinoderms live strictly in marine environments. %PDF-1.5 %���� Its shell consists of two halves, called the valves. It encloses a space, which is called mantle cavity (= pallial cavity). Single layered epidermis is usually ciliated. There are around 100,000 recognized extant species of molluscs. Statocysts (balancing organs) may be present. In some molluscs like Pila, due to torsion (twisting) during growth, the adults become asymmetrical. Body is segmented and bilaterally symmetrical. C head is located on foot . Share Your PPT File. The body is divided into head, dorsal visceral mass, and ventral muscular foot and mantle. Sepia is edible. Phylum MOLLUSCA, class Polyplacophora: (poly - plax - pherein) CHITONS, 500 spp., (all similar in ecology & morphology) mm's - >35cm, common at low levels on rocky shores, can crawl when immersed in water, clamp to a substrate when emmersed. The shell of sepia is used as a source of calcium for pet birds. shell. Phylum Mollusca and Phylum Echinodermata belong to the Kingdom Animalia. Sepia, Loligo, octopus, nautilus, (pearly nautilus). Phylum Mollusca. Shell is internal. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. It is a thin, fleshy fold of dorsal body wall more or less covering the body. Their body has a cavity. (i) Shell is present in many individuals, (ii) In some forms, a lungs is present for pulmonary respiration, and. monas- one, plax- plate, pherein- bearing): The shell is spoon or cup shaped. B head is fused with thorax . It will also be used to setup a comparison between the major classes (Gastropoda, Bivalvia, Cephalopoda, and Polyplacophora) and to introduce discussion about the role of the mollusks in the ecosystem. However, it is not a legal authority for statutory or regulatory purposes. Its shell yields an excellent quantity of lime the shells of the fresh water mussels are used in the manufacture of buttons. Shell is external (Nautilus), internal (sepia) or absent (octopus). Answer Now and help others. The six major mollusc classes CLASS 1 : MONOPLACOPHORA CLASS 2 : AMPHINEURA CLASS 3 : SCAPHOPODA CLASS 4 : GASTROPODA CLASS 5 : PELECYPODA OR BIVALVIA CLASS 6 : CEPHALOPODA 6. 1. They exhibit organ system level of organization. Blood is usually blue due to the presence of a copper- containing blue respiratory pigment called haemocyanin. It is open type. Our mission is to provide an online platform to help students to share notes in Biology. 8. ... Download Phylum - Mollusca MCQ Question Answer PDF ... Cephalopoda is a class of animals in which . These classes are distinguished by, among other criteria, the presence and types of shells they possess. Body is covered by a calcareous shell and is unsegmented with a distinct head, muscular foot and visceral hump. It is nocturnal and herbivorous. Neopilina is a “connecting link” between Annelida and Mollusca. 1) Gastropods (snails, whelks, cowries, slugs) 2) Bivalves (clams, oysters, scallops, shipworms) 3) Cephalopods (octopus, squid, cuttlefish, nautilus) • Shell is cup-shaped , formed of one piece only . Class 1. The giant squid has the largest eye in the animal kingdom. The first class includes the gastropods, a group of land snails and slugs. Gastropoda (Gk. It damages seedlings, tender shoots and leaves. Thus, the annelids are the evolutionary precursor of molluscs. They are oviparous. amphi- both + two neuron = nerve): Animal Kingdom, Biology, Diversity, Living Organism, Phylum Mollusca. (iii) Nervous system consists of cerebral, visceral, pleural and pedal ganglia. 0 Amphineura (Gk. Neopilina has 8 pairs of muscles, 5 or 6 pairs of gills, and 5 pairs of nephridia. torsion). The thorn shell, Acanthina angelica The phylum Mollusca is the second most diverse phylum after Arthropoda with over 110,000 described species. Cephalopoda are addressed in a separate section due to the large number of species and their importance as a ishery. • Foot is broad , flat , disc-like with flat creeping sole . Introduction The Mollusca , common name of molluscs or mollusks, are a large phylum of invertebrate animals. Phylum Mollusca are divided into six classes. endstream endobj startxref Do eukaryotic cells have restriction endonucleases? Class 1. Welcome to BiologyDiscussion! Class 11 Biology Animal Kingdom: Phylum Mollusca: Phylum Mollusca. Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda.The members are known as molluscs or mollusks (/ ˈ m ɒ l ə s k /).Around 85,000 extant species of molluscs are recognized. gaster- belly, podos- foot): The early embryo is symmetrical but during development the body twists showing torsion so that the body becomes asymmetrical. In this article we will discuss about the general characters and classification of Phylum Mollusca. Amphineura (Gk. The sexes are generally separate but some are hermaphrodite. They usually show bilateral symmetry. ��}z5ױI�F�:����%����TR�CѧN(�C����bk3c��1��W3��� _��g�U�[,����G.�t�ѻJX�qz�;�:7��J67:]=���H;UO Privacy Policy3. The phylum Mollusca has about 100,000 described species and potentially 100,000 species yet to be described (Strong et al., 2008). eucoelomates; protostomes great size variation great diversity & adaptive radiation This class comprises more than 15000 species including mussels, oysters, … Dentalium is found burrowing in sand. �``hʄ�� _� A pear-shaped ink-sac containing the ink-like fluid is present. Mollusca is comprised of approximately 200,000 described living species, making it one of the largest animal phyla, and consists of eight living classes that are predominantly marine, with gastropods and bivalves the only ones to have spread to freshwater. Class 2. Class 6. Mollusks can be segregated into seven classes: Aplacophora, Monoplacophora, Polyplacophora, Bivalvia, Gastropoda, Cephalopoda, and Scaphopoda. 4. Name the types of nitrogenous bases present in the RNA. devilfish. There are present filamentous tentacles called the captacula, which are useful in feeding.
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