Download Worksheet Mollusks Read book and answer questions

Mollusks Worksheet
Read pages 585-593 and answer the following questions
1. How long ago did the mollusks evolve? They evolved 600 million years ago.
2. In what range do mollusks live? From deep ocean trenches to mountain brooks to the tops of trees.
3. Why are such different creatures classified together in one phylum? They all have a trochophore
larva and they are soft bodies animals that have an internal or external shell
4. What is the mollusk larva called? Trochophore larva
5. Which other phylum also develop this same kind of larva? Phylum Annelida
6. What does this indicate about mollusk evolution? Mollusks and Annelids are closely related
7. List some other reasons why mollusks are grouped together. Mollusk bodies have 4 basic parts;
Foot, mantle, visceral mass and shell
8. Fill in the table below:
Part
Description
Foot
Soft muscular structure that usually contains mouth and structures
associated with feeding
Shell
Protective structure made of CaCO3(calcium carbonate)
Visceral mass
Contains the internal organs
Mantle
Thin delicate layer that covers the mollusk body like a cloak and
secretes calcium carbonate for the shell.
9. What is a radula? The rasping tongue found in mollusks
10. How is the radula used by a) carnivores?
b) herbivores?
They use it to bore
They use the radula to scrape algae off
holes in the shells of
rocks
other mollusks
11. What do filter feeders use to gather food? They use their gills.
12. Compare and contrast open and closed circulatory systems.
Same:
Different:
Carry blood
In open circulatory systems blood does not always stay in blood vessels
Distribute O2 & nutrients while in closed circulatory systems blood always stays in blood vessels
13. Complete the table below about mollusk reproduction:
Internal Fertilization
External Fertilization
Where it takes place
Inside the body
Outside the body
Description of how it is
Cephalopod fertilization
Eggs and sperm are released
done
takes place inside the
into open water in enormous
female’s body
numbers
Hermaphroditic gastropods
pair up and fertilize each
other’s eggs
Organisms that use this
Snails
Bivalves
form of reproduction
Tentacled mollusks
14. In the diagram below:
a. Colour the gut blue
b. Colour the lungs red
c. Colour the tentacles green
d. Colour the eyes purple
e. Colour the reproductive
organs yellow
f. This type of organism is called
a/an _Hermaphrodite___
g. Can you locate a major design flaw in
this body design? The anus is near the
respiratory pore
15. Describe the lifestyle of most bivalves. They
live on the bottom of the ocean and burrow in
sand or mud.
16. How do bivalves make pearls? If a grain of sand gets caught between the mantle and shell, the
mantle glands cover it with mother of pearl. After many years the grain of sand gets completely
coated and is called pearls.
17. Label the diagram of a clam below:
3.
5.
4.
6.
2.
7.
8.
1.
10.
9.
18. Describe the appendages of cephalopods. They have eight flexible tentacles equipped with round
sucking disks that are used to grab and hold fish and other prey. In addition to the tentacles squids
also have two long arms with suckers on the end.
19. Describe movement in cephalopods. They use jet propulsion by drawing water into their
mantle cavities that they then force out through their tube like siphon.
20. Decide of the organisms listed below are gastropods, bivalve, cephalopods or other (leave blank)
Gastropod
Bivalve
Cephalopod
Organism

Nudibranch

Cuttlefish

Slug

Clam

Sea hares
Mussel
Chitons
Octopus
Snail
Shipworms
Scallop
Abalone
Oyster






