Phylum mollusca has been divided into following six classes on the basis of foot, shell and mantle. This section describes the defining features of mollusks. Here is an overview of the phylum mollusca that includes the classification of mollusca, mollusca characteristics, and mollusca examples. Brusca and others published phylum mollusca find, read and cite all the research you need on. A free powerpoint ppt presentation displayed as a flash slide show on id. 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.
Understand the taxonomic relationships and major features of mollusks. Mollusca 251 class scaphopoda the appropriately named tusk shells are a distinctive group of molluscs found in association with soft and unconsolidated substrata into which they burrow. Phylum annelida contains a variety of worms and their relatives. Currently there are an estimated 75 thousand species, plus 35 thousand species in the fossil record. They can be found in terrestrial regions as well as in the depths of the seas. Aplacophora, monoplacophora, polyplacophora, bivalvia, gastropoda, cephalopoda, and scaphopoda. Relationships of mollusca evolutionary hypotheses for the major groups of molluscs are controversial largely because of the extreme diversity in the phylum.
Classification of phylum mollusca biology libretexts. To date, there is no documented evidence on the diversity of molluscan fauna found by intertidal rocky. Its fun if you can understand the need for it and how its done. Phylum mollusca characteristics, examples, classification and importance soft bodied animals general characters of phylum mollusca. The veliger has many of the characteristic structures of adult molluscs including a head, foot, and shell. Phylum mollusca reproduction most mollusks are dioecious, with external fertilization most mollusks have a larval stage depending on species, fertilization may. Mollusca is the secondlargest phylum of invertebrate animals after the arthropoda. Around 85,000 extant species of molluscs are recognized. Visit the mollusca pages on the tree of life for more on molluscan systematics. Phylum mollusca characteristics, examples, classification. Phylum mollusca characteristics, classification and examples. Dec 10, 2015 general characteristics of phylum mollusca mollusca molluscus soft bodies study of mollusca is called malacology.
Morphological hypotheses generally placed the caudofoveata and solenogastres as plesiomorphic based on their simple wormlike body plan and lack of a shell kocot et al. Mollusks have bilateral symmetry, no body cavity, soft bodies, and sometimes have a. They includes slow moving snails and slugs bivalved shell with two parts clams and highly active cephalopods. Start studying characteristics of phylum mollusca diaz. Animals in this phylum have soft bodies, many have a. Some animals that you are familiar with like snails, octopuses, squids, oysters, clams etc. Of the roughly 100,000 known mollusk species, about 70,000 are gastropods, and 20,000 are bivalves or 90 percent of the total. It is estimated that 23 percent of all known marine species are mollusks.
This volume is a reprint of a classic book about nautilus, first published in 1987, with an introductory chapter summarizing all of the work on nautilus and its habitat since the publication of. Mollusks are the largest marine phylum, comprising about 23% of all the named marine organisms. Pdf mollusca characteristics feeding and digestion. Mollusca medical definition merriamwebster medical. Echinodermata are so named owing to their spiny skin from the greek echinos meaning spiny and dermos meaning skin, and this phylum is a collection of about 7,000 described living species. Learn more about annelids here and take a short quiz. Phylum mollusca class gastropoda class bivalvia class cephalopoda class polyplacophora class scaphopoda.
The number of fossil species is estimated between 60,000 and 100,000 additional species. Most molluscs are marine, some freshwater, some terrestrial. The proportion of undescribed species is very high. Atkinson lj and sink kj eds field guide to the ofshore marine invertebrates of south. Phylum mollusca a free powerpoint ppt presentation displayed as a flash slide show on id. Class polyplacophora better known as chitons or coatofmail shells, these.
Phylum mollusca is a very diverse 85,000 species group of mostly marine species. Dec, 2019 of the roughly 100,000 known mollusk species, about 70,000 are gastropods, and 20,000 are bivalves or 90 percent of the total. What are the important characteristics of mollusca. Mollusca authors dai herbert1, georgina jones2 and lara atkinson3 citation herbert dg, jones gj and atkinson lj.
The three most universal features defining modern molluscs are a mantle with a significant. Circle the letter of each sentence that is true about mollusks. Download objective type questions of phylum mollusca pdf visit our pdf store. 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. Mollusks live in marine, freshwater and terrestrial. The size of the annelids can range from a few millimetres to an amazing three metres in length.
Phylum mollusca mcq multiple choice question and answer phylum mollusca mcq with detailed explanation for interview, entrance and competitive exams. The body of molluscs is unsegmented with a distinct head, muscular foot. They are generally marine and mostly asymmetrical animals figure 4. Phylum mollusca objective type questions pdf download. Firstever observations of a live giant squid in the wild pdf. The group mollusca, established by cuvier 1798, comprises of almost 1,00,000 species and is the second largest animal. Many organisms belonging to this phylum have a calciferous shell. Phylum mollusca is one of the most conspicuous invertebrate animals.
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. They are selective predators of microinvertebrates living within the sediment. Most molluscs also have a straplike ribbon of minute teeth the radula inside the mouth, but this characteristic. The animals belonging to the phylum mollusca have softbodies, triploblastic and bilaterally symmetrical. Mollusca is a phylum of species that range from the cuttlefish to the sea snail. Phylum mollusca is the predominant phylum in marine environments.
The phylum mollusca is the secondlargest animal phylum, with over 100,000 species. It is from these two families that most people derive their general perception of mollusks as small, slimy creatures equipped with calcareous shells. Having over 17,000 species, phylum annelida is a large phylum. In this article we will discuss about the general characters and classification of phylum mollusca. Origin, phylogeny and classification of the phylum mollusca. The bodies are generally very soft and are covered by the hard exoskeleton. They are found everywhere from marine and freshwater habitats to damp soil. Synopsis of phylum mollusca molluscs identifying characteristics of phylum. There are an estimated 100,000 species of molluscs making them second largest phylum in the animal kingdom, having fewer species than only the phylum arthropoda. Molluscs are a phylum of mostly marine invertebrates that includes octopus, mussels, clams, snails, chitons, squid and many more animals. The term mollusca was first applied by aristotle to cuttle fish. Echinoids are preyed on by several species including lobsters, crabs, starish, certain lineish and octopus. They exist in various environments including marine waters, fresh waters and also in moist terrestrial areas. 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.
Atkinson lj and sink kj eds field guide to the ofshore marine invertebrates of south africa. General characteristics of phylum mollusca mollusca molluscus soft bodies study of mollusca is called malacology. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Cnidaria authors kerry sink1, mark gibbons2, megan laird3, and lara atkinson4 citation sink kj, gibbons mj, laird mc and atkinson lj. Kingdom mollusca learn about snails, slugs, squid, and cuttlefish and several other invertebrates found in the phylum mollusca. There is also a mantle cavity into which the velum can be. Phylum echinodermata general characteristics and classification.
Zoology mollusks block 1 nabinger purpose this lesson is intended to introduce the phylum mollusca and to go over its general physical characteristics. Body is divisible into three regions head, a visceral mass, and ventral foot. To know more about mollusca, keep visiting byjus website or download byjus app for further reference. Examples include the pandora clams, cuspidariids and watering pot shells. The body of molluscs is unsegmented with a distinct head, muscular foot and visceral hump. Internal fertilization occurs when the species functions as both sexes and is thus a hermaphrodite. Molluscs are soft bodied animals, often with hard shells for protection. Species in the mollusca phylum reproduce either through external or internal fertilization. Aplacophora, monoplacophora, polyplacophora, bivalvia, gastropoda, cephalopoda, and. Phylum mollusca is a very diverse 85,000 species group of mostly marine species, with a dramatic variety of form. These are primitive multicellular animals and have cellular level of organisation. The phylum mollusca is composed of variety of organism. It also describes the basic mollusk body plan and the characteristics of the three main classes of mollusks. This is all covered with a mantle also known as a pallium that typically secretes the shell.
Annelids are also known as ringworms or segmented worms. Molluscs phylum mollusca are invertebrates that include animals such as squid, octopuses, cuttlefish, nudibranchs, snails, slugs, limpets, sea hares, mussels, clams, oysters, scallops, as well as many lesser known creatures. Many sea urchins cling onto rocks, however, some species live in sandy habitats and are known as burrowing urchins. Gastropoda, or snails, belonging to the phylum mollusca, have colonized highly contrasting habitats with single taxonomic orders represented in marine, freshwater, and terrestrial domains. The eggs and larvae of sea urchins are preyed upon by zooplankton. Mollusks are the second largest phylum in the animal kingdom after the phylum arthropoda. Ppt phylum mollusca powerpoint presentation free to. In this article we will discuss about phylum mollusca. Mollusks have bilateral symmetry, no body cavity, soft bodies, and sometimes have a shell. They have a muscular foot, a mantle which produces a shell and a visceral mass which contains all of their internal organs. Introduction to mollusca and the class gastropoda mark pyron department of biology, ball state university, muncie, in, usa kenneth m. Water enters through minute pores ostia in the body wall into.
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