phylum mollusca characteristics

Linnaeus (1758) coined the name of this phylum. Natural pearls are produced when a small foreign object gets trapped in between the mollusk's body shell and mantle. General Characteristics of Phylum Mollusca They have a bilaterally symmetrical body (exception: gastropods body asymmetrical) and show organ system grade of organization. It overlaps the … amzn_assoc_search_bar = "true"; The tentacles have a bulbous end which is known as captaculae. 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The largest living bivalve species is giant clam (Tridacna gigas) which can grow up to 47 inches (1,200 mm) in length and more than 200 kg in weight. The foot is reduced and modified into tentacles. amzn_assoc_tracking_id = "mywebsit03240-20"; Body without cavity. amzn_assoc_ad_mode = "search"; 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. f. None of these. The most general characteristic of molluscs is they are unsegmented and bilaterally symmetrical. The captaculae are used to grasp and capture prey. The vast Phylum Mollusca contians a great diversity of speciation and, with that, many different and unique characteristics. They have a well-developed vision to detect their pray or potential enemies. 2 0 Phylum Mollusca (Mollusks) Etymology: From the Latin Molluscus, meaning soft of body. Body is divisible into head (absence in pelecypoda and scaphopoda), dorsal visceral mass, ventral muscular foot and mantle. Sense organs are eyes, tentacles, osphradium and statocyst. Respiration takes place through one or more gills or ctenidia, lungs (pulmonary sac) or general body surface in the terrestrial forms. They are mostly found in marine and fresh water. Body without cavity. DESCRIPTION OF THE PHYLUM MOLLUSCA (LINNAEUS 1758) EUKARYA>UNIKONTA>OPISTHOKONTA>ANIMALIA>METAZOA>BILATERIA>PROTOSTOMATA>SPIRALIA>TROCHOZOA>EUTROCHOZOA>MOLLUSCA: Mollusca (mo-LUS-ka) is derived from the Latin word molluscus, which means soft. Body possesses a through gut with mouth and anus. They have a mantle. But some species live in freshwater and terrestrial habitats.They play an important role in the lives of humans because they are the source of food for many people. 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). Glochidium larva also occurs during the parasitic stage for some species (mussels and clams). Image courtesy of Jan Delsing, Wikimedia Commons The phylum Mollusca is the second-largest animal phylum, with over 100,000 species. This is adapted for numerous locomotive purposes such as burrowing into sediment, gliding or swimming (nudibranchs), attachment to hard surfaces (limpets) and directing jet propulsion (cephalopods). These deposits are derived from substances in the water and harden over-time. They have both ends open single conical shell. To which phylum do cephalopods belong, Mollusca, Nematoda, or Annelida? In this case, sexual reproduction occurs. They have a bilaterally symmetrical body with a spiral or coiled shell. Examples: Turritella cumberlandia, Diastoma insulaemaris, Epitonium charlestonensis, Pila globosa (Apple snail). in Biology Monoplacophora 2. In this case, the shell is a hard calcareous structure, made up of calcium carbonate. Class # 1. They have a well-developed head. Many, however, occur in fresh water and some even in damp soil. They have bristles (setae). Head consists tentacles and compound eyes. Development may be direct or indirect. They have open type blood circulatory system with heart (one or two auricles and one ventricle) and aorta. ). They show direct or indirect development with trochophore or veliger larval stages. 10 Important Characteristics of Mollusca are given below: One of the characteristics of mollusca is having a soft body and is protected by a hard shell that is bilaterally symmetrical. A cuttlefish, a coleoid cephalopod, moves primarily by undulating its body fins. They are exclusively marine organisms and have a worldwide distribution. They are characterized by a shell which is divided into left and right valves. Very few are terrestrial found in damp soil. Caudofoveates are small, deep-sea mollusks that burrow into soft bottom sediments. As others in the phylum Mollusca, bivalves have a shell that is made up of deposits of Calcium Carbonate. This phylum has 50,000 living species. They bear hard beaks for tearing and devouring their prey. Excretion by a pair of kidneys or organs of Bojanus and pericardial gland or Keber’s organ. Phylum Mollusca (Mollusks) Characteristics They are essentially aquatic mostly marine, few freshwater and some terrestrial form. Characteristics of Mollusca: Bilaterally symmetrical. They are filter feeder but some are scavengers. They have a large and flat muscular foot which is used for creeping, swimming or burrowing. Learn vocabulary, terms, and more with flashcards, games, and other study tools. General Characteristics of Phylum Mollusca: 1. amzn_assoc_ad_type = "smart"; 4 Osphradia- chemoreceptor to test chemical nature of the water. They have a well-developed nervous and circulatory system with the concentration of nerve ganglia. amzn_assoc_ad_mode = "manual"; Molluscs are present in most Nearctic freshwater habitats other than hypersaline lakes, which are colonized by only a few snail species (Assiminea spp. g. Mollusca. Gastropoda 4. They are also known as tusk shells, elephant’s tusk, elephant’s tooth or tooth shells. They have a modified foot. Most of the animals of this class inhabit rocky intertidal or shallow subtidal zones but few live in more than 7000 meters depth. This makes finding universal traits an extraordinarily difficult task. The blood circulatory system is open with a heart and for excretion, a pair of kidneys are present that open to the pallial cavity. Study of Mollusca is called Malacology. amzn_assoc_search_bar_position = "bottom"; The shell is either external, internal or absent. The following are present in all modern molluscs: The dorsal part of the body wall is a mantle (or pallium) which secretes calcareous spicules, plates or shells. There are about 25 living species which all inhabit the deep sea between 175–6400 m depth ranges. Study of molluscan shell is called conchology. amzn_assoc_default_category = "PCHardware"; amzn_assoc_ad_type = "smart"; Circulatory system is closed or open type. amzn_assoc_default_category = "Shoes"; Examples: Octopus abaculus, Loligo vulgaris, Sepia dubia. The marine … The left and right side of the body is equal or identical. 4. It is a cephalopod having, Blood consists of copper containing pigment called haemocyanin. Widely distributed over the world. Among all known marine species, 23% are mollusks. Phylum Mollusca is a very diverse (85,000 species) group of mostly marine species. They have an elongated and bilateral symmetrical body. Example: They have a looped digestive system where the stomach is cone-shaped with long intestine that makes four to six loops before reaching the posteriorly-positioned anus. Mollusca makes the second largest phylum of non-chordate animals including snails, octopuses, sea slugs, squid, and bivalves such as clams, oysters, and mussels. 3.51 A). Digestive system is well developed with a hard chitinous structure, called radula. amzn_assoc_linkid = "df6e3e2dfb2223ece0caaeddeb1e4806"; ADVERTISEMENTS: The following points highlight the six main classes of phylum mollusca. They have no eyes, tentacles, and nephridia but radula is present. It is the second-largest phylum of invertebrates. They are commonly called soft bodied animals. Body Characters:They are triploblastic, coelomate and show bila… They are triploblastic animals with un-segmented (exception: Mantle and shell cover the body and the body has three regions namely: head, ventral foot, and a visceral mass. amzn_assoc_search_bar = "true"; They have elongate-oval and flattened body. But all Molluscs have the same basic structure. Statocysts- for maintaining equilibrium of the body. The v… They include slow-moving snails and slugs bivalved (shell with two parts) clams and highly active cephalopods. They use the ventral muscular foot for locomotion. Most of them inhabit in the marine environment and few are freshwater. amzn_assoc_default_search_phrase = "Tablets"; amzn_assoc_linkid = "8176995fc60e05367dcce2a1fda714d5"; Octopus is known as devil fish. The group Mollusca, established by Cuvier (1798), com­prises of almost 1,00,000 species and is the second largest animal phylum (Fig. The nervous system consists of three pair of ganglia (cerebral, visceral and pedal) with connectives and nerves. amzn_assoc_ad_mode = "search"; The most commonly shared features are often internal. Most bivalves are enjoyed as delicacies, despite the fact that they are benthic level filter-feeders. They do not have a head with no eyes or eyespots. The body is bilaterally symmetrical and covered by a mantle. Generally, the hard calciferous shells of mollusks are used to build awesome jewellery pieces. Amphineura 3. For instance the nervous system structure is for the most part the same in most Mollusca. 5. Excretion takes place by paired metanephridia (kidney). The organisms belonging to phylum Mollusca exhibit the following characteristics: 1. Calcium carbonate secretes from the mantle and forms outer calciferous body shell in most of the mollusks. They have multiple pairs of excretory organs (nephridia) which are arranged serially. 6. Sexes are separate, and they show the larval stage (trocophore larva) in their life cycle. amzn_assoc_linkid = "df6e3e2dfb2223ece0caaeddeb1e4806"; They have a broad ventral foot that is used for suction to rocks and other substrates. amzn_assoc_marketplace = "amazon"; Pelecypoda or Bivalvia or Lamellibranchiata 6. Most species live in fairly deep water within about 4,000 meters depth ranges. Solanogastres, like caudofoveata, are worm-like mollusks that lack shells. Body has more than two cell layers, tissues and organs. The body cavity is known as hemocoel which circulates blood. However, both molluscs and echinoderms are triploblastic, and they possess a complete digestive system. (adsbygoogle = window.adsbygoogle || []).push({}); Copyright © 2020 Microbiology Notes. Some cause diseases or acts as pests like the snails and slugs. So give me some basic point mollusca, Your email address will not be published. Abstract. They are the familiar group of organisms with eight valves on their shells. They have a pseudocoelom. Locomotion takes place by ventral muscular foot. They are mostly aquatic organisms. It is the second largest phylum in the animal kingdom. Their foot is modified into eight arms or two tentacles in the head region. The animals of this phylum are soft-bodied, non-metameric, triploblastic coelomates and fundamentally bilaterally symmetrical invertebrates with a thin fleshy envelope the mantle, around the visceral (internal organs of the body) which may secrete calcareous shell. All Rights Reserved. Sexes are usually separate but some are monoecious. Their brain is large and well-developed in contrast to any other mollusks. They are exclusively deep water marine mollusks and are found in all oceans of the world. All notes of Bacteriology, Virology, Parasitology, Mycology and Laboratory, By Pratiksha Pokhrel Most of them inhabit in the marine environment and few are freshwater. They have a worm-like appearance with no shells. The term Mollusca was first applied by Aristotle to cuttle fish. They are the successful groups in the ocean, freshwater (ponds, streams, marshes, and lakes) and land. They live their adult lives buried in sand or mud. amzn_assoc_default_browse_node = "13900871"; amzn_assoc_placement = "adunit0"; 3. Sense organs consist of eyes, osphradium, tentacles, and. Molluscs show a great variety of form (structure). For example, all mollusks have a mantle. amzn_assoc_title = "Shop Your Products"; With probably around 200,000 extant species, Mollusca is the second-most speciose phylum after Hexapoda. e. Annelida. Very very good . They have metanephridia (kidney) for excretion. amzn_assoc_default_browse_node = "672123011"; amzn_assoc_placement = "adunit0"; amzn_assoc_region = "US"; The body contains eight overlapping dorsal plates. 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. The size of the molluscans varies from less than one millimeter to 20 meters. They have the ability to squirt ink during threatened. December 10, 2015, Please Rate Aschelminthes are pseudocoelomate, bilaterally symmetrical, triploblastic, unsegmented, vermiform, organ- system grade of construction with complete digestive tubes. Your email address will not be published. Scaphopoda 5. Coelom reduced Most viscera concentrated in dorsal visceral mass Body covered by thick mantle (epidermis) which forms a cavity Mantle secretes calcium carbonate shell (or spicules) Large ventral muscular foot Radula (band of teeth in esophagus) Additional classes not covered in lab: … 10:09. In this case, Tentacles are used for capturing prey while arms force prey into the mouth. The head comprises of tentacles and compound eyes. amzn_assoc_placement = "adunit0"; An introduction. Phylum Mollusca and Phylum Echinodermata belong to the Kingdom Animalia. amzn_assoc_search_bar_position = "bottom"; Generally, their foods consist of small organisms such as foraminiferans and young bivalves. amzn_assoc_title = "My Amazon Picks"; There is a between Mollusca and Echinodermata in terms of morphological, physiological and behavioural characteristics. b. Nematoda. Body possesses a through gut with mouth and anus. amzn_assoc_title = "Shop Your Products"; 1 Visible among the many aspects of an open clam are the posterior and anterior adductor muscles. Some mollusks such as bivalves and gastropods produce valuable pearls. They exhibit organ system level of organization. They vary in size from giant squids and clams to little snails, a millimeter long. The pallial cavity bears many pairs of small-sized gills which surround the foot. https://www.toppr.com/guides/biology/animal-kingdom/phylum-mollusca They have two shells. The nervous system is simple that contains two pairs of lateral nerve cords with several special tiny sensory organs. Most molluscs are herbivorous but some (e.g. Besides these, many scientists use bivalve mollusks as bioindicators of the freshwater and marine environments. Their body has a cavity. The … The mouth contains a rasping structure ‘radula’ with chitinous teeth for scraping or cutting food. Examples: Mya arenaria (soft-shell clam),  Mercenaria mercenaria (hard clam). The hard calciferous shells of mollusks are used to build awesome jewellery pieces. 2)Body has more than two cell … General Characteristics of Phylum Mollusca (Mollis or molluscs: soft) Kingdom: Animalia; Habitat: Mostly aquatic and few are terrestrial; Body is soft without segmentation; Grade of organization: Organ system grade; Germ layer: Triploblastic; Symmetry: BIlaterally symmetry; The body is divided into head, muscular foot and visceral mass. All freshwater molluscs have one or two shells composed of a thin outer layer of proteinaceous perisostracum and a strong inner layer of mostly crystalline calcium carbonate. External or internal fertilization occurs. The animals of this phylum are soft-bodied, non-metameric, triploblastic coelomates and fundamentally bilaterally symmetrical invertebrates with a thin fleshy envelope the mantle, around the visceral (internal organs of the body) which may secrete calcareous shell. Lamarck coined the term Molluscus.

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