Fish 310 Introduction to Echinoderms




Дата канвертавання19.04.2016
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FISH 310

Introduction to Echinoderms
The echinoderms are an amazing group of marine invertebrates that tend

to have pentamerous symmetry. The language for describing the surfaces of an echinoderm different than that used for most animals; in echinoderms there is an ‘aboral’ and ‘oral’ surface that correspond to what we would normally think of as the dorsal and ventral surfaces. The surface with the mouth is called the oral surface, the other side is the aboral surface.


Echinoderms are awesome.

1. Watch the video showing the oral (bottom) and aboral (top) surfaces of a live sand dollar (subphylum echinozoa; class echinoidea). The irregular lines radiating from the mouth are the food grooves. Draw or describe the spines on the different oral and aboral sides. What do you think are the functions of the spines on the each side? (2 points)

2. Look at the dried tests (dried endoskeleton) of the sand dollars. How is the pentamerous design of echinoderms expressed in these animals? What might be the function of this part? Looking at a live sand dollar will help answer this question. (1 point)
3. Compare the test of a sand dollar (Dendraster) to that of a sea urchin (both from subphylum echinozoa; class echinoidea). Name one way they are similar and one way they differ (1 point)

4. Examine the aboral surface of a seastar (subphylum asterozoa, class stelleroidea, subclass asteroidea) under a dissecting scope. Draw the following:



  • pedicellaria (moveable, compound ossicles that serve as pincers. There may be more than one type)

  • papulae (fleshy extensions for respiration)

  • spines (extension of the calcareous endoskeleton)

Place a strand of your hair against the pedicellaria. Describe the reaction. (2 points)

5. Now examine the aboral surface of a sea urchin (subphylum echinozoa, class echinoidea) under the dissecting scope. Name two ways that the pedicellaria, papulae, or spines differ between the urchin and the seastar? (1 point)

6. Using a tube foot of the sea star touch the sea urchin. How do the pedicellariae and spines react? (1 point)


7. Examine the oral surface of the sea urchin. Draw the Aristotle’s lantern, peristomial membrane, and buccal podia. If it looks different than you expect, indicate why/ how. (2 points)

8. Examine a sea cucumber specimen (subphylum echinozoa, class holothuroidea). How is the usual echinoderm pentamerism (5 part body plan) expressed? (1 point)


9. Now compare it to the other species of cucumber. How have they modified the radial body plan? (1 point)

10. How do you think the different body plans of the various species of cucumbers relates to their lifestyle in the wild? (1 point)

11. Watch how the sea cucumbers breathe and describe it. How is this different from

respiration in the seastars? (1 point)

12. Examine the structure of a preserved brittlestar (subphylum asterozoa, class stelleroidea, subclass ophiuroidea). List two ways in which they differ from seastars (subphylum asterozoa, class stelleroidea, subclass asteroidea). (1 point)

13. Feel the different textures of some of the various seastars. How might that relate to the environment where they live? (1 point)

14. Use a key to identify four seastars. (2 points)

15. Please examine echinoderm development by looking at the slides set up under compound scopes. (2 points). Draw the following:









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