Mollusks live in marine, freshwater and terrestrial. In this article we will discuss about phylum mollusca. They are selective predators of microinvertebrates living within the sediment. Brusca and others published phylum mollusca find, read and cite all the research you need on researchgate. This then is the plan of a basic unevolved mollusc. The bodies are generally very soft and are covered by the hard exoskeleton. Mollusks are softbodied invertebrates of the phylum mollusca, usually wholly or partly enclosed in a calcium carbonate shell secreted by a soft mantle covering the body. Freshwater molluscs are common animals in lakes and streams. Phylum mollusca the mollusca include chitons, clams, oysters, snails, slugs, squids, nautilus and octopuses. Molluscs can be divided into five principal classes, namely gastropoda, bivalvia, scaphopoda. Download objective type questions of phylum mollusca pdf visit our pdf store. The body of molluscs is unsegmented with a distinct head, muscular foot and visceral hump.
Gastropods comprise approximately 70,000 described liv ing species of marine, terrestrial, and freshwater snails and slugs. Gastropoda single shelled cowries, cones etc bivalvia two shelled like clams, mussels etc aplacophora solenogasters monoplacophora segmented limpets polyplacophora or amphineura as it was earlier called chitons scaphopoda tusk shells. There is no segmentation and name means softbodied. What are some representative species from each class. Mollusca is the largest marine phylum, comprising about 23% of all the named marine organisms. Molluscs are soft bodied animals, often with hard shells for protection. Find, read and cite all the research you need on researchgate. A study of the type series of nautilus pompilius linnaeus, 1758 mollusca, cephalopoda, nautilida svetlana v. Structure soft bodied animals name from latin word mollus meaning soft most are protected by a hard shell made of calcium carbonate have a reduced internal cell or have lost the shell completely during evolution. Phylum mollusca is a very diverse 85,000 species group of mostly marine species. Phylum mollusca mcq multiple choice question and answer phylum mollusca mcq with detailed explanation for interview, entrance and competitive exams. Many, however, occur in fresh water and some even in damp soil. Most are marine, but many are freshwater and some live on the land. There are six classes of which three are more prominent.
Synopsis of phylum mollusca molluscs identifying characteristics of phylum. Pdf freshwater life is the first comprehensive, illustrated field guide to aquatic life in the wider southern african region. Which of the following is not a class within phylum mollusca 3. They are one of the most diverse phyla, second only to. Its fun if you can understand the need for it and how its done. They are the largest marine phylum, comprising about 23% of all marine organisms.
Classification of mollusca april, 97 1 victor millard a classification of the living mollusca which was compiled by kay cunningham vaught and published by american malacologists, inc melbourne, florida 32902, usa in 1989 was used as the basis for this compilation. The proportion of undescribed species is very high. The phylum mollusca includes six classes, but the three main classes. This basic plan is changed and adapted, for the requirements of different lifestyles, almost beyond recognition in some of the 6 classes of mollusca. Either the giant squid or the colossal squid is the largest known invertebrate. Mollusca is the secondlargest phylum of invertebrate animals after the arthropoda. One shell, tubular, curved in less than 12 circle and opening on both ends, tapered so that one end is considerably smaller than the other. Name a phylum from a previous lab whose members filter feed. Currently there are an estimated 75 thousand species, plus 35 thousand species in the fossil record. The phylum mollusca is divided into 8 classes with varying number of species in them. Cephalopod molluscs, such as squid, cuttlefish and octopus, are among the most neurologically advanced of all. Despite the diversity of form and function among the molluscs, all members of this group have the same basic body plan. The list includes 195 species belonging to 9 groups of which crustacea is the most diverse with 73 species, followed by mollusca with 69 and echinodermata with 18.
Classes in phylum mollusca phylum mollusca is a very diverse 85,000 species group of mostly marine species, with a dramatic variety of form. Classification of phylum mollusca biology libretexts. These animals are found in marine, terrestrial, and freshwater habitats, but a presence of water or humidity is a critical factor for their survival, especially in terrestrial habitats. In this article we will discuss about the general characters and classification of phylum mollusca. Introduction to mollusca and the class gastropoda chapter pdf available. Characteristic features of phylum mollusca they are bilaterally symmetrical. Phylum mollusca objective type questions pdf download. Pdf on jan 1, 2009, maria gabriela cuezzo and others published mollusca. Hopefully i will get something written about each class in the not too distant future. Many molluscs also live in fresh water and terrestrial environments. Phyla mollusca and annelida no prep warm ups, bell ringers, or inserts for interactive notebooks. However, the earliest molluscs probably arose in the precambrian, and nothing is known about what they were like.
This section describes the defining features of mollusks. Gastropoda find, read and cite all the research you need on researchgate. Phylum mollusca, class cephalopoda general info kaphale head, pous foot, 600 extant, 7,500 spp. Name two classes you learned this week that have members who filter feed. Pdf the paper gives an overview of the modern hypotheses on the origin of the phylum mollusca and the formation of its main classes. Cephalopod molluscs, such as squid, cuttlefish and octopus, are among the most neurologically advanced of all invertebrates. 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. These warm ups cover the characteristics of each phylum, the classes of each phylum, the mollusk and annelid body plan, the clam, the earthworm, and more. Classes caudofoveata, helcionelloida extinct class and rostroconchia extinct class will not be treated in this section at this time. Class polyplacophora better known as chitons or coatofmail shells, these.
Flattened body has 8 dorsal shell plates, usually visible dorsally. Most bivalves are filter feeders taking all floating particles out of the water column. Cephalopod molluscs such as squid, cuttlefish and octopus are among the most neurologicallyadvanced of all invertebrates and either the giant squid or the colossal squid is the largest known invertebrate species. What covers and protects visceral mass in mollusca and used for gas exchange, excretion, and the release of reproductive products. Mollusks are the second largest phylum in the animal kingdom after the phylum arthropoda. Around 85,000 extant species of molluscs are recognized. Phylum annelida contains the class polychaeta the polychaetes and the class oligochaeta the earthworms, leeches, and their relatives. Porifera includes multicellular animals which exhibit cellular level of organisation and have. Phylum mollusca general characteristics 50,000 or more species of molluscs. It also describes the basic mollusk body plan and the characteristics of the three main classes of mollusks. The phylum is usually divided into 9 or 10 taxonomic classes, of which two are entirely extinct. A free powerpoint ppt presentation displayed as a flash slide show on id.
Cns is a ring of ganglia in head area with paired nerves and ganglia extending to other parts of the body. Body does not have two valves hinged together dorsally. There are around 100,000 recognized extant species of molluscs. Here is a commonly used classification for molluscs. They can be found in terrestrial regions as well as in the depths of the seas. The phylum mollusca is the secondlargest animal phylum, with over 100,000 species. Aplacophora, monoplacophora, polyplacophora, bivalvia, gastropoda, cephalopoda, and scaphopoda. Approximately 16,500 species have been described in phylum annelida. Mollusks are the largest marine phylum, comprising about 23% of all the named marine organisms. 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. Mollusca example stomach with grooves for guiding food bibliography.
Mollusca are a large welldefined group that is fundamentally bilaterally symmetrical even though the distortion may be great. Study 22 terms phylum mollusca 5 classes flashcards quizlet. Classification can be great fun and not as utterly boring as it sometimes turns out to be. The members of this group have adapted either on land or in water. It is a major group in the animal kingdom as regards the number which occupies next to arthropods. See more ideas about sea creatures, ocean creatures and underwater life. The visceral mass of gastropods take a 180 degree turn during development. Williams and others published phylum mollusca, class bivalvia.
Mollusks kingdom animalia phylum mollusca means soft ch 27. All mollusks have a soft body, although some are also covered by a hard shell. The phylum includes earthworms, polychaete worms, and leeches. Phylum mollusca is a group of invertebrates which has fascinated man from the dawn of civilization. Members of this phylum have soft, unsegmentated bodies usually enclosed. Includes animals such as squids, snails, oysters, clams and slugs. The body is divided into head, muscular foot and visceral mass. 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. Mussels and clams have a hinged, bivalved shell and are generally suspension andor deposit feeders.
Nov 19, 2019 the name of the phylum is derived from the latin word annellus, which means a small ring. List four adaptations that class cephalopoda has for hunting. The phylum mollusca consists of over 100,000 marine, freshwater, and terrestrial species. Pdf origin and the early evolution of the phylum mollusca. Mollusc simple english wikipedia, the free encyclopedia. Numerous molluscs also live in freshwater and terrestrial habitats. Some grownups cant see magic ponies but children can explanation.
The different classes under phylum mollusca include. Outstanding body features are the shell or calcareous exoskeleton, the mantle, which is a fold of the body wall that lines and secretes the. What phylum is characterized by the presence of a mantle. The phylum mollusca is divided into five main classes. Gastropoda stomachfoot single shell or no shell at all moves via foot muscular action does torsion180 degree counterclockwise rotation for defense largest group has 6 pairs of ganglia. Body does not have 8 dorsal shell plates, may or may not be flattened. Many organisms belonging to this phylum have a calciferous shell. Many mollusks also live in freshwater and terrestrial habitats. 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. Please see following plates for example structures of the mollusca. Media in category mollusca the following 200 files are in this category, out of 972 total. Mnemonic classes and subclasses of phylum mollusca in taxonomy. Along with the insects and vertebrates, mollusks are one of the most diverse groups in the animal kingdom, with nearly 100,000 possibly as many as 150,000 described species. The smallest bivalves are microscopic and the largest are 4 feet across.
Introduction the mollusca, common name of molluscs or mollusks, are a large phylum of invertebrate animals. Freshwater molluscs are classified into gastropods snails and freshwater limpets and several groups of. Heart is dorsal to the alimentary canal with lateral openings in the abdominal region and. South africa has recorded 347 sponge species, comprising around 4% of sponge diversity worldwide. However, local taxonomic knowledge of this phylum is largely incomplete.
The number of fossil species is estimated between 60,000 and 100,000 additional species. Phylum mollusca class gastropoda class bivalvia class cephalopoda class polyplacophora class scaphopoda. The references in that work have not been transferred to this one. The phylum mollusca is typically divided into nine or ten taxonomic classes, of which two are entirely extinct. Molluscs are found in nearly all freshwater and marine. They all have a muscular foot that serves a variety of different purposes depending on the specific animals lifestyle. They are bilaterally symmetrical, triploblastic, segmented and coelomate animals. Circle the letter of each sentence that is true about mollusks. Over twothirds of all named species on earth are arthropods figure 4. Body is divisible into three regions head, a visceral mass, and ventral foot. The phylum mollusca has about 100,000 described species and potentially 100,000 species yet to be described strong et al. Movement of this class within phylum mollusca exhibits walking. They are highly diverse, not just in size and in anatomical structure, but also in behaviour and in habitat the phylum is usually divided into 9 or 10 taxonomic classes, of which two are entirely extinct.