Biology 104 Study Guide: Lab 22 – Introduction to Invertebrates
Take Note!
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READ! Know words in bold.
See live specimens first!
o Living specimens: Hydra, planarian, vinegar eels, rotifer
See slides and specimens.
Answer questions and fill in blanks unless told to SKIP.
Learn names of organisms (genus name unless told otherwise), including correct spelling,
named on study guide ONLY. Be able to recognize.
Each person may take TWO slides at a time.
Do not forget to READ INDEX CARDS ON BACK TABLES.
“wm” on slide means “whole mount” (whole organisms on slide).
Compare what you see in lab to the manual, Photographic Atlas, classroom charts, and
textbook.
DO THIS FIRST!
Each lab group (2 students) will prepare to feed one Hydra and one Planaria.
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Find a tiny culture plate (Petri dish) in your lab drawer. Use the bottom for the Hydra,
and the top for the planarian. Use the droppers that go with each jar on the back tables.
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Without disturbing the jar, use a Hydra pipette to remove ONE Hydra, and place it with a
small amount of water into the bottom of the small Petri dish.
o When disturbed, the Hydra will curl up into a tiny ball.
o Place dish on your lab table and leave it undisturbed until the Hydra relaxes and
stretches out again.
o Compare appearance to poster near emergency shower.
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Use a Planaria pipette (large opening) to remove ONE planarian and place it with a small
amount of water into top of the Petri dish.
o Place the dish on a piece of white paper on your lab table to observe the
movements of the flatworm.
o Compare appearance to poster near emergency shower.
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Let animals rest. Continue with Lab 22.
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SECTIONS TO COVER IN LAB BOOK!
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22.1 Evolution of Animals
o Read about evolution of animals.
o Be able to explain Fig. 22.1: Phylogenetic tree.
o Know Comparative Anatomical Features (pg. 293).
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22. 2 Phylum Porifera
o READ. Know words in bold.
o See specimens and compare to charts.
o Know: Anatomy of sponges
 Do question #1.
 SKIP questions 2-3 (pg. 293-294)
o See and know Figure 22.2 – Sponge Anatomy.
o Read paragraphs that accompany Prepared Slides only.
o See DEMO: sponge spicules - Grantia. Sketch one spicule (question #2 pg. 295).
o Fill in Conclusions (pg. 295)
o See and read Diversity of Sponges (pg. 295).
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22.3 Phylum Cnidaria
o READ. Know two basic body forms and words in bold.
o See specimens and compare to charts.
o Read Anatomy of Cnidarians.
o Anatomy of Hydra: identify parts, Fig. 22.5.
o Observation: Anatomy of Hydra
 Preserved Hydra observation- SKIP
 #2 Prepared Slides:
 Hydra, budding
 #3 Living Hydra specimens
 Do questions 1-4 with your live specimen.
 Each pair of partners: Get ONE dissecting microscope (marked
with a letter instead of a number) from cabinet. Instructions for
using it begin on pg. 16.
 GENTLY place the dish containing the Hydra onto the stage of
the dissecting scope and observe.
 BE AWARE THAT KEEPING THE LIGHTS ON THE Hydra
WILL BEGIN TO COOK IT! IT MAY CURL UP IF IT GETS
TOO WARM. So observe without lights until it starts to do
something interesting.
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When Hydra is relaxed, add one Daphnia (water flea) to the dish.
If Daphnia passes close to the tentacles, the Hydra may discharge
cnidocytes (sting the flea to death) and then use its tentacles to
force the water flea into its gastrovascular cavity (see chart in back
of room).
o Fill in Conclusions (pg. 298).
o Diversity of Cnidarians: see specimens
 Give body form of each type of cnidarians: hydroid, jellyfish, sea
anemone, coral
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22.4 Phylum Platyhelminthes (Flatworms)
o READ. Fill in blanks.
o See specimens and compare to diagrams and charts.
o Planarians
 Read paragraph.
 Know anatomy of planarians-Figure 22.8.
 DEMO slide planarian.
 Gastrovascular cavity is filled with tiny black pellets. Find:
eyespots, auricles, gastrovascular cavity, pharynx
 SKIP cross-section of planarian (pg. 300).
 Observation: Free-living planarian (Answer questions 1-5.)
 Use a small speck of egg yolk (this size: O) instead of a piece of
liver. Watch eating behavior. You may use the dissecting scope to
try to see pharynx, but DO NOT keep worm in bright light for
long!
o Fill in Conclusions and Table 22.1.
o Read about Tapeworms (pg. 302).
 Review life cycle and answer questions.
o Observe preserved parasitic flatworms on the tables.
 Know parasitic flatworm anatomy-Figure 22.12.
o Read Fluke Diversity and Anatomy.
 Skip Observation #1.
 If available, view fluke specimens.
o Read Planarians Versus Tapeworms and Flukes.
 KNOW Table 22.2.
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22.5 Phylum Nematoda (Roundworms)
o READ. Fill in blanks.
o See specimens and compare to charts.
o Know anatomy of roundworms.
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Ascaris: See preserved specimens only (step 1).
 SKIP DISSECTION: We used to dissect Ascaris until it was found
that the eggs survive and remain viable in the preservative.
 Skip dissection but read steps 2-7 only.
 Read about Trichinella.
 See specimens if available.
 Read about Filarial Worms.
 Vinegar eels: Living specimens:
 Make wetmount slide using one drop from the jar. Take slide and
cover slip back to the jar. Remove lid for the shortest time
possible. Observe movement of vinegar eels with low power.
o SKIP: Conclusion: Anatomy of Roundworms
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22.6 Phylum Rotifera (Rotifers)
o READ.
o DEMO slide. See three regions: head, trunk, foot. Also see ciliated corona.
o Living specimens: Make wetmount slide. Look for telescoping action of body,
and movement of corona.
 Answer questions 1-6.
KNOW ANSWERS TO LABORATORY REVIEW.
Know: Phylum Porifera: sponge
Phylum Cnidaria: Hydra, Obelia, jellyfish, coral, sea anemone
Phylum Platyhelminthes: planarian, tapeworm, fluke
Phylum Nematoda: vinegar eels
Phylum Rotifera: rotifer
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