Three big protostome phyla annelids, arthropods, molluscs 2. Session objectives phylum vii mollusca general characteristics examples of molluscs classification of phylum mollusca. Mollusca soft bodied are marine or freshwater or terrestrial johnston coined the name mollusca. The bodies are generally very soft and are covered by the hard exoskeleton. Mollusca molluscs a phylum of coelomate see coelom invertebrates comprising classes which are morphologically quite diverse, including the amphineura, bivalvia, cephalopoda, gastropoda.
The smallest bivalves are microscopic and the largest are 4 feet across. Learn mollusca 2 classes with free interactive flashcards. Most bivalves are filter feeders taking all floating particles out of the water column. They can be found in terrestrial regions as well as in the depths of the seas. Understand the taxonomic relationships and major features of mollusks learn the external and internal anatomy of the clam and squid.
The body is divided into head, muscular foot and visceral mass. Many of these first molluscs were but simple, wormlike animals. Mollusca is the second largest phylum of invertebrate animals. Only bivalves and gastropods have been able to adapt to life in fresh water bivalves. Bivalvia tend to be very stationary throughout their lives, hence the very long life cycles, but this leads to them having a. Pdf origin and the early evolution of the phylum mollusca. Radula is going to drill holes in oyster and clam shells. Phylum mollusca is divided into eight classes, all but one of which are extant.
Some grownups cant see magic ponies but children can explanation. Classification of phylum mollusca biology libretexts. Pdf the paper gives an overview of the modern hypotheses on the origin of the phylum mollusca and the formation of its main classes. 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.
Annelida post lab 7 phyla mollusca and annelida name sec 11 point name the four classes of phylum mollusca then name a. Phylum mollusca objective type questions pdf download. The molluscs mollis soft are softbodied animals with a hard external or internal shell. Phylum mollusca the mollusca include chitons, clams, oysters, snails, slugs, squids, nautilus and octopuses. I have recorded the very best easy lecture for you on the topic of phylum mollusca that will be very helpful for you to understand better you can find the. Animals in phylum mollusca have an open circulatory system, but also often have a heart that pumps blood. Choose from 500 different sets of mollusca 2 classes flashcards on quizlet. Mollusca is the secondlargest phylum of invertebrate animals after the arthropoda. Classification kingdom animalia phylum mollusca 4 classes. Consensus phylogeny of mollusc classes as supported by the phylogenomic anlayses of kocot et al. All animals of the phylum mollusca have bilateral symmetry.
Freshwater molluscs are classified into gastropods snails and freshwater limpets and several groups of. Mollusks belong to the phylum mollusca and make up the second largest group of invertebrates animals lacking backbones after the arthropods. Phylum mollusca mcq multiple choice question and answer phylum mollusca mcq with detailed explanation for interview, entrance and competitive exams. In this article we will discuss about the phylogeny and phylogenetic relationship of phylum mollusca. Chitons or sea cradles elongated, dorsoventrally flattened marine, on rocky intertidal substrates head reduced in size shell consists of 8 dorsal plates chitons are common inhabitants of hard. Classification can be great fun and not as utterly boring as it sometimes turns out to be. Body structure of phylum mollusca, class xi, biology. Classes in phylum mollusca phylum mollusca is a very diverse 85,000 species group of mostly marine species, with a dramatic variety of form.
In addi tion to three familiar molluscan classes comprising the clams bivalvia, snails and slugs gastropoda, and squids and octopuses cephalopoda, five. Many, however, occur in fresh water and some even in damp soil. The heart is key to keep the blood pressure regulated. A study of the type series of nautilus pompilius linnaeus, 1758 mollusca, cephalopoda, nautilida svetlana v. General characteristics of phylum mollusca mollis or molluscs. Around 85,000 extant species of molluscs are recognized. The phylum mollusca has about 100,000 described species and potentially 100,000 species yet to be described strong et al. Molluscs can be divided into five principal classes, namely gastropoda, bivalvia, scaphopoda. Many organisms belonging to this phylum have a calciferous shell. Monoecious and dioecious, but usually produce eggs that hatch. You will be amazed to know that the size of the molluscans can range from 20 metres to one millimetre, with a few microscopic animals too.
Bilateral symmetrical, unsegmented with definite head 2. Structure soft bodied animals name from latin word mollus meaning soft. Molluscs comprise the familiar animals commonly known for both their shells and fine seafood, including snails, clams. In this article we will discuss about the general characters and classification of phylum mollusca. The below mentioned article provides notes on mollusca snail. Aplacophora, monoplacophora, polyplacophora, bivalvia, gastropoda, cephalopoda, and scaphopoda. 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. Aplacophora, monoplacophora, polyplacophora, bivalvia, gastropoda, cephalopoda, and. Today the phylum of mollusca is divided into eight different classes, six of which are exclusive marine living in the sea. Phylogeny and phylogenetic relationship of phylum mollusca. About 100 million years later, during the ordovician period, at least six of the seven classes of molluscs represented today were present. Body structure of phylum mollusca, class xi, biology, chapter animal kingdom extramarks. Its fun if you can understand the need for it and how its done. The first class includes the gastropods, a group of land snails and slugs.
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