MOLLUSK
Review
Name one of the three classes of
mollusks you learned about.
Gastropods, cephalopods, Bivalves
The free swimming ciliated larva
found in most aquatic mollusks is
Trochophore
called a _________________
The space around the heart is called
the _____________
pericardial space (cavity).
In mollusks the heart and organs
for digestion, excretion, and
reproduction are found in this
body region.
Visceral mass
The octopus, squid, and chambered
nautilus belong to this group of
Mollusks.
cephalopods
This bump on the
dorsal surface of a
clam near the hinge is
umbo
the _______
Pigment cells in the outer mantle
layer in cephalopods that can change
color for camouflage.
chromatophores
Identify the colored
structures.
Anterior & posterior
adductor muscles
The nervous system in a clam consists
of _____________________________
3 pairs of ganglia
connected by 2 pairs of nerve cords
Type of body cavity found in
mollusks.
No coelom
pseudocoelom
eucoelom
eucoelom
The powerful muscles that open and
close a clam shell are the ___________
Adductor muscles
(posterior and anterior)
Identify the body system each organ belongs to:
Excretory
Kidney __________________
Reproductive
Testes/ovary ____________________
Respiratory
Gills ___________________
Digestive
Digestive gland ___________________
Nervous
Ganglia ____________________
Circulatory
Heart ____________________
What keeps water moving over
the gills in a clam?
Cilia on gills move water
A flexible tongue-like strip of tissue
covered with tough, abrasive teeth
that point backwards found in some
mollusks.
radula
Compare Digestive and Nitrogen waste
DIGESTIVE
WASTE
NITROGEN
WASTE
Made where?
In digestive tract
By body cells
Comes from?
Left over from
undigested food
Removed by
what body system?
Leaves body as?
Digestive
Feces
breakdown of proteins
during metabolism
Excretory
ammonia, urea,
OR uric acid
This structure is
the
_____________
intestine
Only cephalopod with a shell
Chambered nautilus
Name the group of mollusks
that does NOT have a radula.
bivalves
Layer of epidermis lining the
shell of a clam
mantle
#2
#1
#3
#2 = ________________________
Anterior adductor muscle
gills
#3 = _______________________
The process during larval
development in which the visceral
mass in gastropods twists around
180º bringing the mantle cavity,
gills, and anus to the front of the
animal. torsion
open circulatory system.
Clams have a(n)__________
Open
Closed
This part of the clam secretes
the shell.
mantle
bilateral
Mollusks have _________
symmetry.
None
radial
bilateral
Fertilization in clams is __________
both
internal
external
both
Depends on speciesin freshwater clams its usually internal
in marine (ocean) clams its external
Identify this
structure
heart
The circulatory fluid (blood) in a
mollusk is called _______________
hemolymph
Respiratory organ in clams.
gills
The flaps that wave
to move food up
toward the mouth
are called
palps
___________________
The organ that passes through the
pericardial cavity and lies under the
heart is the __________________
intestine
The space between the mantle
and the visceral mass.
Mantle cavity
Which group of mollusks does NOT
have a shell?
Bivalves
cephalopods
cephalopods
gastropods
Organisms that stay in one place
and don’t move around are called
Sessile
___________________
Tell an advantage of having a coelom
compared to a pseudocoelom.
1. Muscles of body wall are separate from those
of gut. (Can move and digest at same time)
2. Coelom provides space for circulatory system
to transport blood
3. Provides a space for organs
invertebrates
Mollusks are _______________
vertebrates
invertebrates
This blue
structure
secretes
the shell.
mantle
Which group of mollusks is
mainly sessile?
Bivalves
gastropods cephalopods
bivalves
T or F
Most clams are hermaphrodites
like earthworms.
False; most clams have separate
sexes
Calcium carbonate in a mollusk’s
________________
shell makes it hard.
An organism with a true coelom is
eucoelomate
called a ______________.
Identify this
structure.
foot
Clams and oysters belong to this
group of mollusks.
Bivalves
Bivalves
gastropods
cephalopods
This structure
starts digestion
and grinds
food.
stomach
Cephalopods are the only mollusks
with a ___________
circulatory system.
closed
open
closed
Fertilization in cephalopods is
internal
external
Internal;
Males use a specialized tentacle to transfer
packets of sperm to the mantle cavity of the
female
Only mollusk group that develops from
egg to juvenile without becoming a
trochophore larva.
cephalopods
Snails and slugs belong to this
group of mollusks.
bivalves
cephalopods gastropods
gastropods
Name one of the functions of
the gills in a clam.
1. Gas exchange (oxygen and carbon dioxide)
2. Trap food particles
Anus
This opening is the _________.
Name part that belongs to each body system:
kidney
Excretory __________________
Digestive ____________________
Palps, Esophagus, stomach,
digestive gland, intestine, anus
Adductors, foot
Muscular ___________________
Ganglia, nerve cords
Nervous ___________________
Heart, hemolymph, hemocoel
Circulatory ____________________
This is the
Digestive gland
________________________.
Another word that means shell is
___________
.
valve
Type of circulatory system in which
blood is NOT enclosed in vessels
open
Tell one body part you might look for
if you wanted to tell direction in a
clam.
UMBO- it’s on the dorsal side
FOOT- triangle points to the anterior end
PALPS- at anterior end
SIPHONS- at posterior end
Which group of mollusks has
chromatophores that can change color
to blend in with the surroundings?
cephalopods
Why does the surface of the gills
have ridges?
Increases surface area to absorb
more oxygen & catch more food
The excretory organ in a clam is the
nephridia
kidney
kidney
flame cells
This is the
Incurrent
__________
siphon
__________
This organ surrounds the stomach
and makes digestive enzymes.
Digestive gland
How does a trochophore larva swim?
Ring of cilia around middle help it move
Body system that removes
nitrogen waste from the body cells
digestive
nervous
excretory respiratory
excretory
#1
#2
#1 = ________________________
foot
mantle
#2 = _______________________
In a clam the coelom mainly
surrounds the heart and is called
pericardial
the______________
cavity.
Organisms that strain food from the
Filter feeders
water like clams are called _________.
predators
filter feeders
scavengers autotrophs
These are located
on the surface of the
clam’s shell and can
Growth rings
help tell it’s age.
This part of the clam
is the ____________
foot
Name a part of the nervous
system in a clam
Ganglia OR nerve cord
This opening is located near the
excurrent siphon so waste is washed
away
anus
#2
#3
#1
#1 = ________________________
Posterior adductor muscle
mantle
#3 = _______________________
This is the
____________
Excurrent
siphon
____________
Organ in a clam is where nutrients
are absorbed.
Digestive gland
Most organisms in this class of
mollusks have 1 shell (or none)
gastropods
PHYLUM that clams, octopus, slugs,
and snails belong to
MOLLUSCA OR Mollusk
Tell one way the nervous system in a
clam is like that of an earthworm
Both have ganglia
Both have a nerve cord
(clam has 2 pairs)
Tell one way the reproductive system
in a clam is different from an earthworm
Earthworms
hermaphrodites
direct development
external fertilization
Clams
have 2 sexes (male & female)
indirect development (larva)
internal/external fertilization
The 3 functions of the digestive gland
are to __________________
Make digestive enzymes (bile)
Finish digestion
Absorb nutrients
The excretory organ in a clam is the
______________
kidney
This space you see when you opened your
clam is called the ________________
mantle cavity
Coelom
pericardial space
mantle cavity
The intestine runs through the
space shown and is covered by
the _________
HEART
HEART
The function of the palps is to
__________________
Move
food to the mouth
anterior
The ____________
end of the clam
is closest to the umbo.
Anterior
Posterior
Identify the body part by its description:
bump on dorsal side of shell
______________
umbo
Edge of shell shortest distance from umbo
______________________
anterior
Tissue that lies on top of tube
running through pericardial space
___________________
heart
Growth rings
Lines on clam shell ___________________
Mantle
Layer lining shell ____________________
The function of the gills is to
__________________
Both A & B are correct
A. remove oxygen from water
B. filter food particles
C. make digestive enzymes
D. excrete nitrogen waste
Clams belong in the
Animalia
______________
Kingdom
Mollusca (mollusks) Phylum
______________
Bivalvia (bivalves) Class
______________
Identify the function of each body part:
Adductor muscles__________________
Open and close shell
Collect and remove digestive waste
intestine ____________________
Gills ___________________
Exchange gases & trap food
digestive enzymes to break down
Digestive gland Make
___________________
food; finish digestion; absorb nutrients
Move food up from gills to mouth
Palps ____________________
Pump hemolymph (blood)
Heart ____________________
Makes shell
Mantle ________________________
True OR False
Clams show cephalization.
FALSE
No true head area- Ganglia/sense organs are spread out
throughout body not concentrated in head
Tube that connects the mouth and
the stomach in a clam
esophagus
The excretory organ in clams is
the __________________
kidney
In Latin the name Mollusca means
“soft body”
________________.
soft
body
two
shells
filter
feeder
little
rings
Identify the body part by its description:
looks like a piece spaghetti inside visceral mass
__________________
intestine
Greenish brown area in anterior end
____________________
Digestive gland
White fans in front of gills
palps
___________________
Long flat structure with ridges (stripes) that
runs along side of clam ___________________
gills
Type of symmetry seen in clams
bilateral
Clams, oysters, octopus, snails, and
squid belong to the
PHYLUM _______________
Mollusca
Kind of circulatory system seen in an
octopus: Closed
open
closed
All other mollusks have an open system
Invertebrates
(no backbone)
Mollusks are _______________
invertebrates
vertebrates
Clams show __________
indirect development
They hatch as trochophore larvae and change into their adult form
direct
indirect
In Latin the name Bivalvia means
“2 shells”
________________.
soft
body
two
shells
filter
feeder
little
rings
What causes oxygen and carbon
dioxide to move into and out of a
clam?
Diffusion moves molecules from where
there is a HIGH concentration to
where there is a LOW concentration
Why do gills have ridges?
Increases surface area
What is the disadvantage of an
OPEN circulatory system?
Less efficient way to transport
nutrients and oxygen
High and low oxygen blood mix
Why is it a good plan for a clam to have
its anus near the excurrent siphon?
Washes away digestive waste
TELL WHICH BODY SYSTEM
EACH PART BELONGS TO
respiratory
gills __________________________
Ganglia _________________
nervous
circulatory
heart___________________
excretory
kidney _________________
adductors ____________________
muscular
digestive
intestine ____________________
protostomes
MOLLUSKS are _____________
protostomes
deuterostomes
Give an example of a mollusk that
is a bivalve
Clams, oysters, scallops
Match the Mollusk with its CLASS
BIVALVIA
Clams, oysters, scallops ___________
Squid, octopus,
CEPHALOPODA
chambered nautilus ______________
Snails, slugs, conchs,
GASTROPODA
Nudibranchs
______________
With a few exceptions:
2
Bivalves have _____
shell(s)
Most 1shell(s)
Gastropods have _____
few 0
0
Cephalopods have ____
shell(s)
(Except nautilus)
Name 3 body systems that use the
mantle cavity as an exit
Digestive-anus releases feces here
Excretory- Kidney releases urea here
Reproductivesperm and eggs are released here (external)
Or sperm and eggs join here and larva exits
(internal)
Respiratory also uses this spacegills are located here
COMPARE:
Earthworms
Clams
RESPIRATORY
Breathe
through skin
gills
CIRCULATORY
Aortic arches
closed
heart
open
NERVOUS
1 pr cerebral ganglia
1 ventral nerve cord
3 pr ganglia
2 pr nerve cords
COMPARE:
Earthworms
Clams
true
True;
pericardial
cavity
Absorbs nutrients?
intestine
Digestive
gland
EXCRETORY
nephridia
kidney
COELOM ?
TELL 3 characteristics of ALL Mollusks
eucoelomates
invertebrates
protostomes
Soft bodies
Bilateral symmetry
trochophore larvae (if indirect)
Name the colored structure:
palps
Give its function:
Move food trapped on gills up
to mouth
Name the colored structure:
mantle
Give its function:
Secrete shell
Name the colored structure:
foot
Give its function:
locomotion
Name the colored structure:
Visceral
mass
Give its function:
Contains body organs
Name the colored structure:
heart
Give its function:
Pump hemolymph (blood)
Name the colored structure:
Pericardial
cavity(space)
This could also be called the
_____________
coelom
Name the colored structure:
Digestive
gland
Give its functions:
Make bile, finish digestion, absorb
nutrients
Name the colored structure:
anus
It is the exit opening for which
Body system?
digestive