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Hydra Lab
Objective
 Observe the structure of a Hydra
 Observe Hydra’s response to stimuli
 Learn reproductive methods used by the Hydra
Definitions
 Monoecious
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Dioecious
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Hermaphrodite
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Sessile
Materials
 Pipette
 Hydra culture
 Petri dish
 Spring water
 Hand lens
 Toothpick
 Vinegar
 Hydra food
 Microscope
Procedure
Drawing a Hydra
1. Use the dropper to remove one hydra from the culture.
2. Place the hydra in a petri dish and add enough spring water to cover the hydra.
3. Use the hand lens to examine the hydra. Locate the mouth and tentacles.
4. Place the petri dish under the microscope using the lowest light possible.
5. Make a labeled drawing of the hydra in Box A in your Data section.
Observing Hydra’s response to stimuli
1. Gently touch the hydra with a toothpick.
Observe the response of the hydra as you touch it
along the stalk, along the tentacles, and as you touch it at the base. Record in Data section
of Box A how the hydra responded to each stimuli.
Feeding a Hydra
1. Add one or two Daphnia to your hydra dish and observe the hydra catching its food.
2. Draw a diagram of the feasting event with a written description in Box B in your Data
section.
Observing Hydra’s response to vinegar
1. Observe the hydra as 1 drop of vinegar
is added to the petri dish near but not on the Hydra.
Draw and Record your observations in the Data section Box C. This will be done as a
demonstration
Data
Observing Hydra’s response to stimuli
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Box A
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Box B
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Box C
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Questions
 What one characteristic sets the Cnidarians apart from other phyla?
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What body form did your observe with the Hydra?
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What type of symmetry does the Hydra exhibit?
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How is the Hydra a more advanced animal than the sponge?
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What is the purpose of nematocysts?
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What are the functions of the amoebocyte?
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What animals belong to Class Hydrozoa?
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What animals belong to Class Scyphozoa?
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Form a conclusion as to why you think the Hydra responded the way it did to the vinegar.
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How does the Hydra asexually reproduce?
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How does the Hydra sexually reproduce?