1. For each pair of terms, explain how the meanings of the terms differ.
a. ossicle and test b. tube foot and pedicellaria c. stone canal and ring canal d. madreporite and atriopore
2. Explain the relationship between the cardiac stomach and the pyloric stomach in sea stars.
3. Choose the term that does not belong in the following group, and explain why it does not belong: tube foot, bipinnaria, radial canal, and ampulla.
4. Word Roots and Origins The word pyloric is derived from the Greek pyloros, which means "gatekeeper." Using this information, explain why the term pyloric stomach is a good name for the structure that the term describes.
Understanding Key Concepts
5. Explain why echinoderms are thought to have evolved from bilaterally symmetrical ancestors.
6. Identify the functions for which echinoderms use their tube feet.
7. Compare feeding in crinoids and basket stars.
8. Compare the ways that sea urchins and sand dollars are adapted to their environment.
9. Describe how the sea cucumber transports food to its mouth.
10. Explain why sea stars are of economic importance.
11. Summarize the process of feeding and digestion in the sea star.
12. Compare sexual and asexual reproduction in sea stars.
13. Summarize how pharyngeal pouches have become modified through evolution in aquatic chordates and in terrestrial chordates.
14. Interpret the significance of the notochord and the postanal tail to aquatic chordates, such as the lancelet.
15. Explain why members of the subphylum Urochordata are called tunicates.
16. JX concept MAPPING Use the following □ □ □ terms to create a concept map that sequences the path of water through the water-vascular system of a sea star: water, radial canal, madreporite, ring canal, tube foot, and stone canal.
17. Forming Reasoned Opinions Scientists have found many echinoderm fossils from the Cambrian period, but they have found few fossils of other species from this period. What might explain the large number of fossilized echinoderms?
18. Analyzing Concepts Sea lilies and sea cucumbers are mostly sessile animals as adults. Their larvae, however, can swim. What adaptive advantage do swimming larvae provide?
19. Inferring Relationships Basket stars are active at night. During the day, basket stars curl up their arms and become a compact mass. What are possible explanations for this behavior?
20. Interpreting Graphics Identify the structures labeled "A-F" in the diagram below.
21. Applying Information Commercial oyster farmers usually want to prevent sea stars from feeding in the oyster beds. In the past, the farmers would control the sea stars by chopping the sea stars in half and throwing them back into the water. Was this a good way to protect the oysters from predation by the sea stars? Why or why not? If not, describe a better method.
Standardized Test Preparation
DIRECTIONS: Choose the letter of the answer choice that best answers the question.
1. In a sea star, gas exchange and excretion of wastes take place by diffusion through which of the following structures?
B. skin gills
D. radial canals
2. Which of the following types of symmetry is characteristic of echinoderms?
H. pentaradial J. pentalateral
3. Which of the following classes of echinoderms most closely resembles the fossils of ancient echinoderms?
4. Which of the following is found in adult tunicates, or sea squirts?
H. spinal cord
J. pharynx with slits
INTERPRETING GRAPHICS: The illustration below shows a sea star and a sand dollar. Use the illustration to answer the question that follows.
5. To which phylum do these animals belong?
DIRECTIONS: Complete the following analogy.
6. Cardiac stomach : digestion :: atriopore :
INTERPRETING GRAPHICS: The diagram below shows a lancelet. Use the diagram to answer the question that follows.
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