Invertebrate Comparative Anatomy Lab
Background: Scientists group animals by their similarities. We will be looking at different phyla of animals
today. These animals will have things in common and they will have differences. We will be looking at
various characteristics of animals and comparing them. Two of these characteristics are as follows:
Body Symmetry (p. 374): There are three types of body symmetry.
Radial Symmetry
Bilateral Symmetry
Asymmetry
Questions:
1. Based on the pictures above explain the difference between these three types of
symmetry.
2. Based on the pictures below explain the difference between the two types of guts.
** Describe each kind on your own sheet of paper drawing a picture of each and writing a
definition.
Type of Gut: There are two types of guts.
Digestive Tracts with Two Openings
Animals eat through mouth and get rid
of waste through anus.
Digestive Tracts with One Opening
Animals eat and get rid of waste
through the same opening.
Part 1: Comparing/Contrasting Characteristics of Animals (make sure you treat the live
animals with care):
1) Compare and contrast the animals in the pictures provided below and the living specimens at
your station. On your own sheet of paper copy the charts below and write down your
observations.
JPhylums Nematoda, Platyhelminthes, and Annelida
Hookworm (Roundworm) – Phylum Nematoda
Planarian (flatworm) – Phylum Platyhelminthes
Earthworm (segmented worm) – see live specimen – Phylum Annelida (p. 390)
Common Name of
Animal
Hookworm
(Roundworm)
Planarian
(flatworm)
Earthworm
(segmented worm)
Body
Symmetry
Type of
Gut
Similarities Between
Three Phyla of Worms
Differences Between Three
Phyla of Worms
Phylum Arthropoda
Spider - Class Arachnid
Fly – Class Insecta
Millipede – Class Myriapoda
Cricket – Class Insecta (see living specimen)
Common Name of
Animal
Sand Crab (Pacific Mole Crab; Class Crustacea)
Crayfish (Class Crustacea p. 409)
Body
Type of
Similarities Between
Differences Between Four
Symmetry
Gut
Four Classes of
Classes of Arthropods
Arthropods
Spider
Fly; Cricket
Millipede
Sand Crab; Crayfish
Phylum Mollusca
Snail – Class Gastropoda
Octopus – Class Cephalopda
Common Name of
Animal
Body
Symmetry
Clam – Class Bivalvia
Type of
Similarities Between
Gut
Three Classes of
Mollusks
Differences Between Three
Classes of Mollusks
Snail
Octopus
Clam
2) Copy the chart below on your paper and write down similarities between the matching
phylums. The “X” boxes should be left blank.
Invertebrate Phylums Similarities:
Phylum
Nematoda
Phylum Nematoda
X
Phylum Annelida
Phylum Platyhelminthes
Phylum Arthropoda
Phylum Mollusca
Phylum
Annelida
Phylum
Platyhelminthes
Phylum
Arthropoda
Phylum
Mollusca
X
X
X
X
3) Copy the chart below on your paper and write down differences between the matching
phylums. The “X” boxes should be left blank.
Invertebrate Phylums Differences:
Phylum
Nematoda
Phylum Nematoda
X
Phylum Annelida
Phylum Platyhelminthes
Phylum Arthropoda
Phylum Mollusca
Phylum
Annelida
Phylum
Platyhelminthes
Phylum
Arthropoda
Phylum
Mollusca
X
X
X
X
Part 2 (Time Permitting): Designing your own observational experiment
1. Develop an experiment to learn about one aspect of each living specimen at your station
(i.e. reaction to warm/cold places, how it moves, how it eats, etc.).
2. Write a hypothesis for your experiment.
3. Write a procedure for your experiment.
4. Write down a list of materials you will need to conduct your experiment.
5. After you have done steps 2-4, show your plan to your teacher (you must do this
BEFORE you do the experiment).
6. Do the experiment, collect data, and write a conclusion about what you observed in your
experiment.
Clean-Up:
1. Bring your living specimens and materials back to the teacher lab station.
2. Wipe down your lab station, dry it, and place everything back where it belongs.
3. Raise your hand so your teacher can check your lab group for completion of the lab.
Invertebrate Comparative Anatomy Lab
Questions:
1. Based on the pictures on the lab sheet explain the difference between these three types of
symmetry. Draw examples for each.
2. Based on the pictures on the lab sheet explain the difference between the two types of
guts. Draw examples for each.
Data Charts:
Phylums Nematoda, Platyhelminthes, and Annelida
Common Name of
Body
Type of
Similarities Between
Animal
Symmetry
Gut
Three Phyla of Worms
Hookworm
(Roundworm)
Planarian
(flatworm)
Earthworm
(segmented worm)
Phylum Arthropoda
Common Name of
Body
Animal
Symmetry
Differences Between Three
Phyla of Worms
Type of
Gut
Similarities Between
Four Classes of
Arthropods
Differences Between Four
Classes of Arthropods
Type of
Gut
Similarities Between
Three Classes of
Mollusks
Differences Between Three
Classes of Mollusks
Spider
Fly; Cricket
Millipede
Sand Crab; Crayfish
Phylum Mollusca
Common Name of
Animal
Snail
Octopus
Clam
Body
Symmetry
Analysis/Conclusion:
Write down similarities (at least 2) between the matching phyla. The “X” boxes should be left
blank.
Invertebrate Phyla Similarities:
Phylum
Nematoda
Phylum Nematoda
Phylum
Annelida
Phylum
Platyhelminthes
Phylum
Arthropoda
Phylum
Mollusca
X
Phylum Annelida
X
Phylum Platyhelminthes
X
Phylum Arthropoda
X
Phylum Mollusca
X
Write down differences (at least 2) between the matching phyla. The “X” boxes should be left
blank.
Invertebrate Phyla Differences:
Phylum
Nematoda
Phylum Nematoda
Phylum Annelida
Phylum Platyhelminthes
Phylum Arthropoda
Phylum Mollusca
Phylum
Annelida
Phylum
Platyhelminthes
Phylum
Arthropoda
Phylum
Mollusca
X
X
X
X
X
Invertebrate Comparative Anatomy Lab
Questions:
1. Based on the pictures on the lab sheet explain the difference between these three types of
symmetry. Draw examples for each.
Radial Symmetry
Bilateral Symmetry
Asymmetry
Many lines cut the
organism (like a
pizza/pie) and the slices
look similar/alike.
One line cuts the organism in
half and the halves look
similar/alike.
Cannot be cut into pieces that
look alike.
2. Based on the pictures on the lab sheet explain the difference between the two types of
guts. Draw examples for each.
Digestive Tracts with Two Openings
Animals eat through mouth and get rid
of waste through anus.
Digestive Tracts with One Opening
Animals eat and get rid of waste
through the same opening.
Data Charts:
Phyla Nematoda, Platyhelminthes, and Annelida
Common Name of
Body
Type of
Similarities Between
Animal
Symmetry
Gut
Three Phyla of Worms
Hookworm
Bilateral
Complete
• All bilateral
(Roundworm)
• Segmented and
Nematoda
Roundworms are
Planarian
Bilateral
Incomplete
round in shape.
(flatworm)
• All have no
Platyhelminthes
legs/arms.
Earthworm
Bilateral
Complete
• All have
(segmented worm)
heads/tails.
Annelida
Phylum Arthropoda
Common Name of
Body
Animal
Symmetry
Spider
Fly; Cricket
Millipede
Sand Crab; Crayfish
Bilateral
Bilateral
Bilateral
Bilateral
Type of
Gut
Complete
Complete
Complete
Complete
Phylum Mollusca
Common Name of
Animal
Body
Symmetry
Type of
Gut
Snail
Octopus
Clam
Asymmetric
Radial
Asymmetric
Complete
Complete
Complete
Differences Between Three
Phyla of Worms
• Flatworms have
incomplete digestive
system.
• Segmented worms have
segments.
• Flatworms are flat.
Similarities Between
Four Classes of
Arthropods
• All bilateral.
• All have a
complete
digestive tract.
• All have body
segments.
Differences Between Four
Classes of Arthropods
Similarities Between
Three Classes of
Mollusks
• All have a
complete
digestive tract.
• All classes have
marine species.
• All have a foot.
Differences Between Three
Classes of Mollusks
•
•
•
•
•
•
•
Spider has 8 legs.
Fly and cricket has 6 legs.
Millipede has 300-400
legs.
Different number of body
sections (Spider – 2,
Fly/Cricket – 3, Millipede
– many).
Snail/Clam are
asymmetric while octopus
has radial symmetry.
Snails have one shell,
clams two shells, octopus
no shell.
Octopus has 8 feet and
clam/snail has 1 foot.
Analysis/Conclusion:
Write down similarities (at least 2) between the matching phylums. The “X” boxes should be
left blank.
Invertebrate Phylums Similarities:
Phylum
Nematoda
Phylum
Annelida
Phylum
Platyhelminthes
Phylum
Arthropoda
Phylum
Mollusca
Phylum Nematoda
X
Bilateral
Symmetry
Bilateral
Symmetry
Bilateral
Symmetry
Complete
Digestive Tract
Phylum Annelida
Complete
Digestive
Tract
X
Bilateral
Symmetry
Complete
Digestive Tract
Complete
Digestive Tract
Phylum Platyhelminthes
Both can
be
parasitic.
Both can
be
parasitic.
X
Both can be
parasitic.
Complete
Digestive Tract
Phylum Arthropoda
Complete
Digestive
Tract
Both have
segmented
bodies.
Bilateral
Symmetry
X
Complete
Digestive Tract
Phylum Mollusca
Both can
be
parasitic.
Both can
be
parasitic.
Both can be
parasitic.
Both have
appendages.
X
Write down differences (at least 2) between the matching phylums. The “X” boxes should be
left blank.
Invertebrate Phylums Similarities:
Phylum
Nematoda
Phylum
Annelida
Phylum
Platyhelminthes
Phylum
Arthropoda
Phylum
Mollusca
Annelida has
segments.
Platyhelminthes
is flat.
Arthropods
have
appendages.
Mollusks have
a “foot”.
X
Platyhelminthes
is flat.
Arthropods
have
appendages.
Mollusks have
a “foot”.
Phylum
Nematoda
X
Phylum Annelida
Annelid bodies
contract and
extend.
Phylum
Platyhelminthes
Platyhelminthes Platyhelminthes
has an
has an
incomplete gut. incomplete gut.
X
Platyhelminthes Platyhelminthes
has an
has an
incomplete gut. incomplete gut.
Phylum
Arthropoda
Nematoda is
not segmented.
Annelid bodies
contract and
extend.
Arthropods have
appendages.
X
Arthropods
have an
exoskeleton.
Phylum Mollusca
Mollusks have
a mantle.
Annelid bodies
contract and
extend.
Mollusks have a
mantle.
Arthropods
have an
exoskeleton.
X