Say more detail about mollusca
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Mollusca is a large phylum of invertebrate animals whose members are known as molluscs or mollusks[Note 1] (/ˈmɒləsk/). Around 85,000 extant species of molluscs are recognized.[2] The number of fossil species is estimated between 60,000 and 100,000 additional species.[3]
Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater and terrestrial habitats. They are highly diverse, not just in size and in anatomical structure, but also in behaviour and in habitat. The phylum is typically divided into 9 or 10 taxonomic classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish and octopus, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species. The gastropods are by far the most numerous molluscs in terms of classified species, and account for 80% of the total.
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➧ Some Phylum in Animal Kingdoms are:-
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❶❭ Porifera:-━━━━━━━━━━━━━━━☟
❱ Body is cylindrical & asymmetrical.
❱ Canal system is present.
❱ Cellular level of organisation.
❱ It is diploblastic.
❱ They reproduce by budding in Asexual Reproduction.
❱ Special cells are choanocytes.
❱ Skeleton is in the form of spicules.
▶Ex:- Sycon & Sponges
❷❭ Coelenterata:-━━━━━━━━━━━━━━━☟
❱ Body is Radially symmetrical.
❱ Canal system is absent.
❱ Tissue grade level of organisation.
❱ Body wall is diploblastic.
❱ Opening served by mouth & anus.
❱ Special Cell or Cnidoblasts.
❱ It occurs in the form of polyp & Medusa.
❱ It have gastrovascular cavity.
❱ It poses tentacles called Nematoblasts.
▶Ex:- Hydra & Jellyfish
❸❭ Platyhelminthes:-━━━━━━━━━━━━━━━☟
❱ Body is bilaterally symmetrical, flattened & Ribbon shaped.
❱ Digestive system is absent or incomplete.
❱ Body cavity is absent.
❱ Body is triploblastic.
❱ It is bisexual or Hermaphrodite.
❱ Respiration is an aerobic.
❱ They possess sućker.
❱ Circulatory or respiratory system is absent.
▶Ex:- Planaria & Tape worm
❹❭ Nematoda:-━━━━━━━━━━━━━━━☟
❱ Body is bilaterally symmetrical or cylindrical.
❱ Body has tissue level of organisation.
❱ It is mostly parasites organism.
❱ Body is triploblastic.
❱ Respiratory or circulatory system is absent.
❱ Sex are separate.
❱ They have tissue but no real organ.
▶Ex:- Ascaris & Hook worm
❺❭ Annelida:-━━━━━━━━━━━━━━━☟
❱ Body is cylindrical, bilaterally symmetrical & metamerically.
❱ Body structure ring-like segment.
❱ Respiration by gills or moist skin.
❱ Body is triploblastic.
❱ Excretory organs are nephridia.
❱ Digestive & circulatory system are well developed.
❱ Locomotory organs are parapodia.
❱ They have true body cavity.
▶Ex:- Earthworm & Leech
❻❭ Arthropoda:-━━━━━━━━━━━━━━━☟
❱ Body is bilaterally symmetrical & segmented.
❱ Exoskeleton shed periodically during growth.
❱ Body is covered with non living exoskeleton.
❱ Body wall is triploblastic.
❱ Body divided into head, Thorax & abdomen.
❱ It have jointed appendages.
❱ It possess compound eyes & antennae.
❱ Respiration by gills, trachea & book lungs.
▶Ex:- Cockroach & Spider
❼❭ Mollusca:-━━━━━━━━━━━━━━━☟
❱ Body is bilaterally symmetrical.
❱ Shell formed of calcium carbonate.
❱ Body covered with mantal & hard shell.
❱ Body is triploblastic & Coelomate.
❱ Body divided into head, foot & visceral mass.
❱ Foot is ventral & muscular.
❱ Respiration by gills or ctenida.
❱ Blood may be Black - blue.
▶Ex:- Octopus & Unio
❽❭ Echinodermata:-━━━━━━━━━━━━━━━☟
❱ Body is radially symmetrical.
❱ Body size is spherical or cylindrical.
❱ Body surface covered with spines.
❱ Body is triploblastic & have coelomic cavity.
❱ It possess power of regeneration.
❱ No head tail right & left side.
❱ Body differentiated into oral & aboral surface.
❱ It have water vascular system.
▶Ex:- Starfish & Antedon
❾❭ Chordata:-━━━━━━━━━━━━━━━☟
❱ Nerve cord hollow tubular & dorsal.
❱ Notochord is present.
❱ Heart is ventral.
❱ Circulatory system is always closed.
❱ RBCs are present.
❱ Endoskeleton is present.
❱ A series of pharyngeal gill-silts present in the pharyngeal wall.
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