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

phylum mollusca classes pdf

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