molluscs zoe wong 6s 27. classification: phylum: mollusca the phylum mollusca contains the following...
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MolluscsMolluscs
Zoe Wong6s27
Classification:Classification:Phylum: MolluscaThe Phylum Mollusca contains the
following subgroups: Class: Aplacophora (solenogasters, deep-sea
wormlike creatures)Class: Bivalvia (clams, oysters, scallops,
mussels)Class: Cephalopoda (squid, nautilus, cuttlefish)Class: Gastropoda (snails, slugs, limpets, sea
hares)Class: Monoplacophora (deep-sea limpet-like
creatures)Class: Polyplacophora (chitons)Class: Scaphopoda (tusk shells)
Class ExampleGastropod chiton
limpetperiwinklesnail
Bivalve musseloyster
Cephalopod squidoctopuse
DiversityDiversityvary from 50,000 to a maximum of
120,000 speciesin 2001 estimated about 93,000 named
speciesHas been estimated that there are about
200,000 living species in total70,000 fossil species80% of all known mollusc species are
gastropods
CharacteristicsCharacteristics Soft-bodied animals Distributes in terrestrial and aquatic habitats An anterior head A ventral foot A dorsal visceral mass Surrounded by a thin fleshy mantle Sheltered in calcareous shell Exoskeleton Carry out respiration by gills Filter feeder
Body StructureBody Structure1 radula 2 mouth
3 shell 4 stomach
5 gonad 6 heart
7 coelom 8 nephridium
9 mantle 10 mantle cavity
11 anus 12 gill
13 foot 14 hemecoel
15 pedal nerve cord 16 gut
17 visceral nerve cord
18 nerve ring
ReproductionReproductioncan be sexualhave both male and female reproductive
organsmating happens during some particular time
and temperaturesnail stabs the skin of the other snail Female snail will then produce eggs internally
and then fertilized by the sperm that has been exchanged
around 1 month for the snail to lay eggs14 days to hatch2 years fro the baby snails to become mature
Evolution - Evolution - CephalopodsCephalopods
Advantages of evolution : the development of more
efficient swimming in response to increasing
competition from predatory fish
better locomotion moving the animal by jet
propulsion colour-changing cells in the
skin
Evolution - GastropodsEvolution - Gastropods
Reasons for evolution :
mechanical stability
defense against predators
sexual selectionclimatic selection
Type of gastropods :
semi-slugs slugs in various other
marine non-marine
gastropods
Human interactionHuman interactionpearls of bivalves and some
gastropodsSea silkTyrian purple dyeFood
SourcesSourcesWikipediaAnswer.comAndrewgrayYahoo!Advanced-level Biology for HK
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