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2. Standardized Test Prep
Resources
Chapter Presentation
Visual Concepts
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Standardized Test Prep

3. Chapter 38 Table of Contents Section 1 Echinoderms
Echinoderms and Invertebrate Chordates
Chapter 38
Table of Contents
Section 1 Echinoderms
Section 2 Invertebrate Chordates

4. Section 1 Echinoderms
Chapter 38
Objectives
Discuss four distinguishing characteristics of echinoderms.
Describe representative species from each of the five classes of echinoderms.
Describe the water-vascular system and other major body systems of echinoderms.
Compare sexual and asexual reproduction in sea stars.

5. Chapter 38 Characteristics
Section 1 Echinoderms
Chapter 38
Characteristics
Echinoderms are radially symmetrical deuterostomes.
Most living species of echinoderms are motile, but some are sessile.
Most echinoderms have:
pentaradial symmetry
an endoskeleton made up of ossicles
a water-vascular system
tube feet

6. Chapter 38 Classification
Section 1 Echinoderms
Chapter 38
Classification
There are about 7,000 species of echinoderms.
There are five major classes of echinoderms:
Crinoidea
Ophiuroidea
Echinoidea
Holothuroidea
Asteroidea

7. Classification, continued
Section 1 Echinoderms
Chapter 38
Classification, continued
Class Crinoidea
Members of the class Crinoidea, called crinoids, include the sea lilies and feather stars.
In both types of crinoids, five arms extend from the body and branch to form many more arms—up to 200 in some feather star species.

8. Classification, continued
Section 1 Echinoderms
Chapter 38
Classification, continued
Class Ophiuroidea
The 2,000 species of basket stars and brittle stars make up the largest echinoderm class, Ophiuroidea, which means “snake-tail.”
Members of this class are distinguished by their long, narrow arms, which allow them to move more quickly than other echinoderms.

9. Classification, continued
Section 1 Echinoderms
Chapter 38
Classification, continued
Class Echinoidea
The class Echinoidea consists of about 900 species of sea urchins and sand dollars.
Echinoidea means “spinelike.”
The internal organs are enclosed within a fused, rigid endoskeleton called a test.

10. Classification, continued
Section 1 Echinoderms
Chapter 38
Classification, continued
Class Holothuroidea
Sea cucumbers belong to the class Holothuroidea.
Holothuroidea means “water polyp.”
Most of these armless echinoderms live on the sea bottom, where they crawl or burrow into soft sediment by using their tube feet.

11. Classification, continued
Section 1 Echinoderms
Chapter 38
Classification, continued
Class Asteroidea
The sea stars, or starfish, belong to the class Asteroidea, which means “starlike.”
Sea stars are economically important because they prey on oysters, clams, and other organisms that humans use as food.

12. Structure and Function of Echinoderms
Section 1 Echinoderms
Chapter 38
Structure and Function of Echinoderms
External Structure
The body of a sea star is composed of several arms that extend from a central region. Two rows of tube feet run along the underside of each arm.
The side of the body where the mouth is located is referred to as the oral surface. The opposite side is called the aboral surface.
The body of a sea star is usually covered with short spines. Surrounding each spine in many sea stars are numerous tiny pincers called pedicellariae.

13. Structure and Function of Echinoderms, continued
Section 1 Echinoderms
Chapter 38
Structure and Function of Echinoderms, continued
Water-Vascular System
The water-vascular system is a network of water-filled canals that are connected to the tube feet.
This coordinated system enables sea stars to climb slippery rocks and capture prey.
Water enters through the madreporite, passes down the stone canal to the ring canal, then through the radial canal to the end of each arm and to the tube feet.
The upper end of each tube foot is a bulblike sac called an ampulla.

14. Structure and Function of Echinoderms, continued
Section 1 Echinoderms
Chapter 38
Structure and Function of Echinoderms, continued
Feeding and Digestion
The sea star can turn its cardiac stomach inside out through its mouth when it feeds.
The cardiac stomach transfers food to the pyloric stomach, which connects to a pair of digestive glands in each arm.
Most sea stars are carnivorous.

15. Structure and Function of Echinoderms, continued
Section 1 Echinoderms
Chapter 38
Structure and Function of Echinoderms, continued
Other Body Systems
Like other echinoderms, the sea star has no circulatory, excretory, or respiratory organ systems.
The nervous system consists mainly of a nerve ring and a radial nerve that runs along each arm.

16. Structure and Function of Echinoderms, continued
Section 1 Echinoderms
Chapter 38
Structure and Function of Echinoderms, continued
Reproduction and Development
Most echinoderms have separate sexes.
Each arm of the sea star contains a pair of ovaries or testes.
Fertilization occurs externally in water.
Each fertilized egg develops into a bilaterally symmetrical, free-swimming larva called a bipinnaria.
Echinoderms have remarkable powers of regeneration.

17. Section 1 Echinoderms
Chapter 38
Anatomy of a Sea Star

18. Characteristics of Echinoderms
Section 1 Echinoderms
Chapter 38
Characteristics of Echinoderms

19. Section 1 Echinoderms
Chapter 38
Pentaradial Symmetry

20. Section 1 Echinoderms
Chapter 38
Water Vascular System

21. Section 1 Echinoderms
Chapter 38
Anatomy of a Sea Star

22. Section 1 Echinoderms
Chapter 38
Types of Echinoderms

23. Chapter 38 Objectives List the major characteristics of chordates.
Section 2 Invertebrate Chordates
Chapter 38
Objectives
List the major characteristics of chordates.
Describe the evolution and classification of invertebrate chordates.
Describe the structure of lancelets.
Describe the structure of tunicates.

24. Chapter 38 Characteristics
Section 2 Invertebrate Chordates
Chapter 38
Characteristics
Chordates, phylum Chordata, are characterized by having a notochord.
In most vertebrates, the notochord is present in embryos but reduced in adults.
In addition, all chordates have the following characteristics during some stage of their life:
a dorsal nerve cord
pharyngeal pouches
a postanal tail

25. Evolution and Classification
Section 2 Invertebrate Chordates
Chapter 38
Evolution and Classification
Echinoderms and chordates likely evolved from a common ancestor.
The phylum Chordata is divided into three subphyla:
Vertebrata
Cephalochordata
Urochordata

26. Evolution and Classification, continued
Section 2 Invertebrate Chordates
Chapter 38
Evolution and Classification, continued
Subphylum Cephalochordata
The subphylum Cephalochordata contains about two dozen species of lancelets.
Lancelets retain their notochord, dorsal nerve cord, pharyngeal pouches, and postanal tail throughout their life.
Lancelets feed by filtering water through the slits in the pharynx. The water leaves the body through the atriopore.

27. Evolution and Classification, continued
Section 2 Invertebrate Chordates
Chapter 38
Evolution and Classification, continued
Subphylum Urochordata
The subphylum Urochordata contains about 2,000 species commonly called tunicates or sea squirts.
As adults, most tunicates are sessile, barrel-shaped filter feeders that live on the sea bottom. They may be solitary or colonial.
Tunicates are hermaphrodites.

28. Section 2 Invertebrate Chordates
Chapter 38
Lancelet Interior

29. Exploration of a Lancelet
Section 2 Invertebrate Chordates
Chapter 38
Exploration of a Lancelet

30. Section 2 Invertebrate Chordates
Chapter 38
Adult Tunicate

31. Characteristics of Invertebrate Chordates
Section 2 Invertebrate Chordates
Chapter 38
Characteristics of Invertebrate Chordates

32. Section 2 Invertebrate Chordates
Chapter 38
Parts of a Chordate

33. Section 2 Invertebrate Chordates
Chapter 38
Anatomy of a Lancelet

34. Section 2 Invertebrate Chordates
Chapter 38
Anatomy of a Tunicate

35. Chapter 38 Multiple Choice
Standardized Test Prep
Multiple Choice
1. In a sea star, gas exchange and excretion of wastes take place by diffusion through which of the following structures?
A. pharynx
B. skin gills
C. atriopore
D. radial canals

36. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
1. In a sea star, gas exchange and excretion of wastes take place by diffusion through which of the following structures?
A. pharynx
B. skin gills
C. atriopore
D. radial canals

37. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
2. Which of the following types of symmetry is characteristic of echinoderms?
F. biradial
G. bilateral
H. pentaradial
J. pentalateral

38. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
2. Which of the following types of symmetry is characteristic of echinoderms?
F. biradial
G. bilateral
H. pentaradial
J. pentalateral

39. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
3. Which of the following classes of echinoderms most closely resembles the fossils of ancient echinoderms?
A. Crinoidea
B. Asteroidea
C. Echinoidea
D. Holothuroidea

40. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
3. Which of the following classes of echinoderms most closely resembles the fossils of ancient echinoderms?
A. Crinoidea
B. Asteroidea
C. Echinoidea
D. Holothuroidea

41. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
4. Which of the following is found in adult tunicates, or sea squirts?
F. eyespot
G. notochord
H. spinal cord
J. pharynx with slits

42. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
4. Which of the following is found in adult tunicates, or sea squirts?
F. eyespot
G. notochord
H. spinal cord
J. pharynx with slits

43. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
The illustration below shows a sea star and a sand dollar. Use the illustration to answer the question that follows.

44. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
5. To which phylum do these animals belong?
A. Chordata
B. Vertebrata
C. Arthropoda
D. Echinodermata

45. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
5. To which phylum do these animals belong?
A. Chordata
B. Vertebrata
C. Arthropoda
D. Echinodermata

46. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
6. Cardiac stomach : digestion :: atriopore :
F. excretion
G. respiration
H. circulation
J. reproduction

47. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
6. Cardiac stomach : digestion :: atriopore :
F. excretion
G. respiration
H. circulation
J. reproduction

48. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
The diagram below shows a lancelet. Use the diagram to answer the question that follows.

49. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
7. Which four structures are the main distinguishing characteristics of chordates?
A. 1, 2, 3, 4
B. 1, 2, 3, 8
C. 2, 3, 4, 6
D. 2, 3, 4, 9

50. Multiple Choice, continued
Chapter 38
Standardized Test Prep
Multiple Choice, continued
7. Which four structures are the main distinguishing characteristics of chordates?
A. 1, 2, 3, 4
B. 1, 2, 3, 8
C. 2, 3, 4, 6
D. 2, 3, 4, 9

51. Chapter 38 Short Response
Standardized Test Prep
Short Response
Echinoderms and chordates are believed to have evolved from a common ancestor.
Describe the evidence that supports this view.

52. Short Response, continued
Chapter 38
Standardized Test Prep
Short Response, continued
Echinoderms and chordates are believed to have evolved from a common ancestor.
Describe the evidence that supports this view.
Answer: Because both echinoderms and chordates are deuterostomes and all other invertebrates are protostomes it is believed that they descended from the same ancestor.

53. Chapter 38 Extended Response
Standardized Test Prep
Extended Response
The fossil record of echinoderms dates to the Cambrian period, more than 500 million years ago. Scientists have observed many well-preserved echinoderm species from this period.
Part A
Based on the fossil evidence, which characteristics did the earliest adult echinoderms have, in terms of symmetry and ability to move?
Part B
Based on your answer to Part A, describe the evolution of echinoderms.

54. Extended Response, continued
Chapter 38
Standardized Test Prep
Extended Response, continued
Answers
Part A
They were bilaterally symmetrical and sessile.
Part B
Present-day echinoderms are radially symmetrical and may move about. Echinoderms probably evolved radial symmetry as an adaptation to their sessile existence. Later, they evolved mobility. Over time, mobile species became more numerous , and today most species can move about. It is unlikely that echinoderms evolved mobility and then radial symmetry, because there would be no selective pressure for radial symmetry in a species that was mobile.