Mollusca is the second largest phylum of invertebrate animals. They are economically important, both beneficially and destructively. Beneficially, molluscs provide food, pearls, decorative shells, pigments, and are used as fishing bait. Destructively, some damage gardens and orchards as plant pests, while shipworms damage boats and wood. Certain molluscs also prey on other molluscs, damaging industries like oyster farming. Overall, molluscs are an important global economic factor.

1. Economic
Importance of
Mollusca
BY DR. PADMINI BISOYI
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2. What is Mollusca?
 Mollusca is the second-largest phylum of invertebrate animals after
the Arthropoda.
Arthropoda
1st
Mollusca
2nd
Chordata
3rd
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3.  Around 85,000 extant species of molluscs are recognized.
 Malacology is the branch of invertebrate zoology that deals with
the study of the Mollusca.
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4. Economic importance of Mollusca
 On the basis of their importance to human Molluscs are
grouped in to two major categories.
1) Beneficial Molluscs
2) Destructive Molluscs
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8. Find ??????
Who are Red Indians ???
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10.  Land snail, Helix pomatia - New York
 Large Foot of Pila and Haliotis – California and South India
 Oyester – USA
Helix pomatia Pila
Oyester
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11.  Commonly used as Food: all over the world
o Mytilus edulis
o Adductor muscle of Pecten
o Mya arenaria
o Venus mercenaria
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12. They are food for other organisms
such as star fish, sponges, leeches,
fish and shore birds.
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13. Commonly used as
sea food in oriental
and Mediterranean
countries.
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14. Devil Fish (Octopus)
Used as food in oriental and Mediterranean countries
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15.  Gastropods for catching fishes.
 Squids are excellent baits for marine
fishes such as Cod in United States.
 Small octopus are used as bait by line
fisherman of Palk Bay
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16.  Red Indian tribes used Dentalium as
money (sawampum). Value of money
varies length wise.
 Shells of gastropods are medium of
barter for Africans.
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17.  Scaphopods, Dentalium, Tooth Shells
are valued as ornaments.
 Nautilus shells are much used for
decorations
 Turban shells used to colored and
used as “cat’s eye”.
Sought as curious
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18. Murex Sp.
Nucella Sp.
Both of them are sources for
Tyrian purple from their juices.
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20.  Contents of ink-sac of
cuttle fish provide a
rich brown pigment
called sepia, used by
the artists.
Normal Coloured art Sepia art
There are different pre existing formats for camera still photos “ Sepia mode” is one of them.
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21.  Gastropod shells are used
for manufacture of buttons.
 Pearls are made by calms
and pearl oyster (most
commonly Pinctada sp. ).
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22.  Nautilus shells are
commonly used in
arts.
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23.  The internal calcareous
shells of sepia, the “Cuttle
Bone” used as medicine
as well as some other
purposes.
 It is a calcium rich
supplement.
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Image from Puri Sea Beach (Cuttle Bones)

24.  There are stories about
Giant Squids and Octopus
cited to play exaggerated
role in popular literatures.
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https://youtu.be/0pz3V0EI_Og

25.  Cephalopods get
credit for two animal
inventions.
1) Jet Propulsion
2) Smoke Screen
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 Recently human have been discovered
the process of jet propulsion which has
been used by cephalopod since millions
of years.

27.  A smoke screen is formed by ejecting a brownish ink into the water. This
diffuses into large area and allows cephalopods to move stealthily through
the smoke searching for its prey or for escape from an enemy.
 It is used by human in world war for escaping from enemy flights.
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The destructive activities of some molluscs are of great
importance to global economy.

29.  Some gastropods like land slugs and snails cause damage to
gardens, orchards, green houses and mushroom beds by feeding
upon the succulent parts of the seedling and plant parts.
 They damage vegetable and flowering plants also.
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30.  The Teredo “The Ship Worm”, a type of bivalve mollusc does
more harm to wooden boats and ships for which the chances of
sinking of the boats and ships increases by 40%.
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31.  Nautica, Buccinum, Murex, Urosalpinx are bore into and feed
on other molluscs. They cause serious damages to pearl and
oyster industries. Urosalpinx also called oyster drill.
 Cephalopods are also predaceous in nature. They feed on
other small molluscs, crustaceans and number of fishes.
 Crabs are favourite food of octopus.
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32. Damage of oyster by
Urosalpinx.
It drill into the oyster and
eat the inner material.
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33.  Members of families Pyramidellidai and
Eullimidae of gastropod are ectoparasites
and suck blood from bivalve molluscs,
polychaetes and echinoderms.
 Stylifer is an endoparasite of the wall of the
echinoderms.
 Entovalva lives in the gut of the sea
cucumber and absorb digested food from
host
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Ectoparasite of Echinoderm

34.  Snails are served as intermediate
hosts in the life cycle of Fasciola
and Schistosoma.
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Fasciola hepatica
Schistosoma

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