The document provides information about bivalves, including that they are molluscs with two shells, most live sedentary lives suspended feeding on food particles pulled in by cilia, and they reproduce both sexually with larval stages and externally for many marine species or internally for freshwater species.

1. NAME MATRIC NO
NIK SYARIHAH BT NIK MUHAMAD ZIN D20101037454
CHANG PEI XIAN D20101037455
NURSYAHIRA AYUNI BT AHMAD ZAMRI D20101037457
NUR ASHIKIN BT ALIAS D20101037459
AIN NABILA BT ABD. MALEK D20101037463
UMI NABILAH BT ISMAIL D20101037464

2. Range in size from tiny
They are bivalved (two
Also called Pelecypoda seed shells 1-2mm in
shelled) mollucs
length to giant size
Mostly are sedentary
suspension feeders
No head, no radula
that depend on ciliary The heaviest bivalve
and very little
currents produced by was recorded at 300kg
cephalization
the gills to collect their
food.

3. Giant Tridacna sp.

4.  The shell are held together by a hinge
ligament.
 Adductor muscles work in opposite to the
hinge ligament.
 When the muscle relax the shell will be
apart.
 Umbo is the oldest part of the shell which
is projecting above the hinge ligament.
 The valves function largely for protection.

6. Mantle
 Folds forming excurrent and incurrent openings for
feeding.
 Some have long, muscular part known as siphon for
burrowing into mud.
 Equipped with cilia to direct water flow over gills for food
and oxygen.
Gills
 Present on both sides.
 Clad by mantle.
 Equipped with cilia also(same function as at mantle).
Foot
 Attaches to visceral mass anteroventrally(at front and
downside).

8. Eyes (ocelli)
 Steely blue in colour.
 Located at edge of mantle.
 Equipped with cornea, lens
and retina.
Organs
 Poor develop sense organs.
 Three pairs of separated
ganglia.
Heart
 Three-chambered heart.
 Pumps blood to gills and
mantle for oxygenation, to
kidney for eliminating
waste.

9. Gland cells and labial
palps secrete copiousa
Gill Oxygen and organic amounts of mucus
material direct to the (entangles food
gills particles suspended
in water entering
gills pores)

10. Ciliated tracts
Mouth move the particle-
laden to the mouth

11. Step 3
The mucus & The suitable
food particles are Enzymes from particles enters to
kept whirling by a extracellular the digestive
Stomach rotation digestion dissolve gland for
gelatinous rod from it in layer intracellular
(crysrtalline style) digestion.

12.  Most bivalves move by extending their slender
muscular foot between the valves.
The foot
The foot shorten
Pump Longitudin
swell and and pull
blood into al muscle
act as the
the foot contract
anchor animal
forward
 Most bivalves use the foot for burrowing and a few
creeping.

13. 

Oysters:
Attach their shells to a surface by secreting
cement.
Mussels:
Attach themselves by secreting a number
of slender byssal threads.
Scallops:
Use their shells for locomotion by clapping
the valves together to move in spurts.

15. Sexes usually separated. Fertilization usually external.
Marine embryo through 3 free-swimming larval stage :
TROCHOPORE, VELIGER LARVA & YOUNG SPAT.
FRESHWATER CLAMS : fertilization is INTERNAL.
Some gill tubes become temporary brood chambers.
LAKES @ STREAM : attachment to fish prevent the
small larvae from moved out of the lake or farther
downstream.

16. If contact
with Sinking to
Glochidia Discharge fish, hitc the bottom
d with hlike a to become
larvae (specialize excurrent ride as sedentary
d veligers) flow parasite adult.
in the
fish’s gills

17. Unique info »
 Some can produce pearl when foreign objects
lodges(stays) in between shell and mantle.
 Mantle will secrete layers of nacre(calcium
carbonate sheets) around the object as a protection
layer.
 Pearl form when small spheres(shells of clams) are
insert together while nacre was secreted.