Name ___________________________________________________________________________ Date_______________ Period_____________
Preserved Echinoderm Lab
Echinoderms are marine organisms with spiny, bumpy, and irregular skin. They have a water vascular system and tube feet for
locomotion. In this lab you will investigate five organisms representative or the four main classes of echinoderms – sea stars, brittle
stars, sea cucumbers, sea urchins and sand dollars.
 All Preserved Organisms (5)
 Place all 5 organisms on your dissecting tray.
 Determine what characteristics led zoologists to place these organisms in the same phyla. Use the dissecting scopes as
necessary.
 List those similarities: __________________________________________________________________________________
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 These organisms are in 4 classes. Determine what unique features they have that led zoologists to place them in separate
classes.
 Unique features of the brittle star: _____________________________________________________________________
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 The brittle star represents class _____________________________________________________________________
 Unique features of the sea cucumber: _________________________________________________________________
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 The sea cucumber represents class __________________________________________________________________
 Unique features of the sea urchin & sand dollar: __________________________________________________________
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 These organisms represent class ____________________________________________________________________
 Unique features of the sea star: _______________________________________________________________________
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 The sea star represents class ______________________________________________________________________
 Describe the body plans of the echinoderms. ________________________________________________________________
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 Sand Dollar
 Draw the aboral and oral side of the sand dollars under the stereoscope.
Aboral TM: ____________
Oral TM: ______________

On the oral side, what is missing from this preserved specimen that would be in a living specimen to aid in locomotion?
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 The sand dollars shape is a benefit to its lifestyle. Describe why this is. ___________________________________________
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 Sea Urchin
 Draw the aboral and oral side of the sea urchin under the stereoscope.
Aboral TM: ____________
Oral TM: ______________

Describe the evidence for penta-radial symmetry in the sea urchin. _______________________________________________
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 How many teeth does your sea urchin have (or should have if they aren’t missing)? _________________________________
 Brittle Star
 Draw the aboral and oral side of the brittle star under the stereoscope.
Aboral TM: ____________
Oral TM: ______________
 Sea Cucumber
 Examine a sea cucumber. Draw the organism and a close up of the cucumbers’ ossicles (the feather tentacle projections near
the mouth)
Organism TM: ________________
Ossicles TM: ____________

The sea cucumber is certainly the “odd ball” of the echinoderm phyla. Why is this? __________________________________
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 What function do the ossicles serve? How does their structure aide this? __________________________________________
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 Sea Star
 Draw the aboral and oral side of the sea star.
Aboral TM: ____________


Oral TM: ______________
The sea star has two types of projections off of its arms – tube feet and modified tube feet. What are each used for? _______
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Why does a sea star walk with the end of its arms curled up? ___________________________________________________
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 Analysis Questions
1. What functions occur on the oral side of the echinoderm? ______________________________________________________
2. What functions occur on the aboral side of the echinoderm? ____________________________________________________
3. What is located in the central disk? ________________________________________________________________________
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4. Describe how an echinoderm eats. ________________________________________________________________________
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5. How do you distinguish a brittle star from a sea star? __________________________________________________________
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Use Figure 16.8 to answer questions 6 – 9. Fill in A – E on the figure.
6. Name one symplesiomorphic character for the phylum Echinodermata. ___________________________________________
7. Name one synapomorphy that can be used to distinguish members of each of the following classes from other echinoderms:
a. Class Crinoidea (Sea Lilies, Feather Stars) _________________________
b. Class Asteroidea (Sea Stars) ____________________________
c. Class Ophuiroidea (Brittle Stars) ____________________________
d. Class Holothuroidea (Sea Cucumbers) _________________________
e. Class Echinoidea (Sea Urchins & Sand Dollars) __________________________
8. Is penta-radial symmetry symplesiomorphic for the phylum? Explain your answer. ___________________________________
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9. Some zoologists think that the Asteroidea and Ophuiroidea should be depicted as being more closely related that they are
represented in Figure 16.8. What characteristic is shared by these groups that could be a derived character uniting these two
classes into a single class? Explain your answer. ____________________________________________________________
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