Name
Class
Date
Skills Practice Lab
Analyzing Sea Star Anatomy
SKILLS
• Observing
• Collecting data
• Inferring
OBJECTIVES
• Observe anatomical structures of an echinoderm.
• Infer function of body parts from structure.
MATERIALS
• disposable gloves
• dissecting microscope
• preserved sea star
• forceps
• dissection tray
• blunt probe
• dissection scissors
• sharp probe
• hand lens
• dissection pins
SAFETY
CAUTION: Always wear safety goggles and a lab apron to
protect your eyes and clothing.
CAUTION: Do not touch or taste any chemicals. Know the location of the
emergency shower and eyewash station and how to use them. If you get
a chemical on your skin or clothing, wash it off at the sink while calling
to the teacher. Notify the teacher of a spill. Spills should be cleaned up
promptly, according to your teacher’s directions.
CAUTION: Glassware is fragile. Notify the teacher of broken glass or
cuts. Do not clean up broken glass or spills with broken glass unless
the teacher tells you to do so.
Before You Begin
Sea stars are members of the phylum Echinodermata, a group of invertebrates
that also includes sand dollars, sea urchins, and sea cucumbers. Echinoderms
share four main characteristics: an endoskeleton, five-part radial symmetry,
a water-vascular system, and circulation and respiration through their coelom.
1. Write a definition for each boldface term above. Use a separate sheet
of paper.
2. You will be using the data table provided to record your data.
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Analyzing Sea Star Anatomy continued
3. Based on the objectives for this lab, write a question you would like
to explore about sea star anatomy.
Procedure
PART A: EXTERNAL ANATOMY
1.
CAUTION: Put on safety goggles, a lab apron, and
protective gloves. As you observe the sea star body
structures, record your observations and your inference of each structure’s
function in the table. On a separate sheet of paper or in your lab notebook,
draw and label the sea star and the structures that you observe.
Data Table
Function of Sea Star Structures
Structure
Observations
Inferred function
Madreporite
Spine
Skin gill
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Analyzing Sea Star Anatomy continued
2. Using forceps, hold a preserved sea star under running water to gently but
thoroughly remove excess preservative. Then place the sea star in a dissecting tray.
3. Refer to a diagram of a sea star in your textbook to locate the madreporite on
the upper surface of the sea star.
4. Use a hand lens to observe the sea star’s spines. Are they distributed in any
recognizable pattern? Are they exposed or covered by tissue? Are they movable or fixed?
5. Use the dissecting microscope to look for small skin gills, If any are present,
describe their location and structure.
6. Examine the sea star’s lower surface. Find the mouth, and use forceps or
a probe to gently move aside any soft tissues. What structures are found
around the mouth?
7. Locate the tube feet. Describe their distribution. Using a dissecting
microscope, observe and then draw a single tube foot on a separate sheet
of paper.
PART B: INTERNAL ANATOMY
8.
CAUTION: Scissors, probes, and pins are sharp. Use care not to
puncture your gloves or injure yourself or others. Using scissors
and forceps, carefully cut the body wall away from the upper surface of one
of the sea star’s arms. Start near the end of the arm and work toward the
center.
9. Find the digestive glands in the arm you have opened. Then, locate the short
branched tube that connects the digestive glands to the pyloric stomach.
10. Cut the tube that connects the digestive glands to the stomach, and move the
digestive glands out of the arm. Look for the reproductive organs.
11. Locate the two rows of ampullae that run the length of the arm.
12. Carefully remove the body wall from the upper surface of the central region
of the sea star. Locate the pyloric stomach and the cardiac stomach.
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Analyzing Sea Star Anatomy continued
13. Remove the stomachs and find the ring canal and the radial canals. In which
direction does water move through these canals?
14.
Dispose of sea stars and sea star body parts in the waste container
designated by your teacher. Do not put lab materials in the trash unless
your teacher tells you to do so.
15.
Clean up your work area and all lab equipment. Return lab equipment to
its proper place. Wash your hands thoroughly before you leave the lab
and after you finish all work.
Analyze and Conclude
1. Analyzing Results What type of symmetry is found in the sea star?
2. Inferring Relationships What is the relationship between the ampullae
and the tube feet?
3. Making Predictions How does a sea star use its stomach during feeding?
4. Making Predictions If the ring canals and radial canals did not function
properly, how would this affect the sea star’s ability to move and feed?
5. Further Inquiry Write a new question about echinoderms that could be
explored with another investigation.
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128
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TEACHER RESOURCE PAGE
Skills Practice Lab
Analyzing Sea Star Anatomy
Teacher Notes
TIME REQUIRED 50 minutes
SKILLS ACQUIRED
Identifying/Recognizing Patterns
Collecting Data
Interpreting
Communicating
RATING
Teacher Prep–3
Student Setup–2
Concept Level–2
Cleanup–3
Easy
1
2
3
4
Hard
SCIENTIFIC METHODS
In this lab, students will:
Make Observations
Analyze the Results
Draw Conclusions
Communicate the Results
MATERIALS
Materials for this lab can be ordered from WARD’S. Use the Lab Materials
QuickList Software on the One-Stop Planner CD-ROM for catalog numbers
and to create a customized list of materials for this lab. You will need one preserved sea star, dissection tray, set of dissecting instruments, and hand lens or
dissecting microscope for each student or lab group. Set up labeled containers
for the disposal of sea star body parts, dissecting pins, and gloves.
SAFETY CAUTIONS
Review all safety symbols with students before beginning the lab. Make sure students wear safety goggles, gloves and a lab apron, and wear this protective gear
yourself when handling preserved specimens. Caution students to use care when
working with sharp instruments. Caution students to keep their hands away from
their faces during the lab. Make sure students wash their hands before leaving
the lab.
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Video Labs
Title
TEACHER RESOURCE PAGE
Analyzing Sea Star Anatomy continued
TIPS AND TRICKS
Leave sea stars in a flowing water bath for at least 4 hours to remove preservative before the lab begins. Demonstrate for students safe techniques for using dissection instruments and dissecting pins. Encourage students to observe other
students’ specimens and to note external and internal differences between individuals of a single species.
ANSWERS TO BEFORE YOU BEGIN
1. echinoderm—a radially symmetrical marine invertebrate that has an
endoskeleton, such as a sea star, a sea urchin, or a sea cucumber
endoskeleton—an internal skeleton made of bone and cartilage
five-part radial symmetry—a body plan in which five similar parts of an
animal’s body are organized in a circle around a central axis
water-vascular system—a system of canals filled with a watery fluid that
circulates throughout the body of an echinoderm
coelom—a body cavity that contains the internal organs
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt Program
Science: Biology
Title
351
BiologyChapter
Video Labs
Title
TEACHER RESOURCE PAGE
Name
Class
Date
Skills Practice Lab
Analyzing Sea Star Anatomy
SKILLS
• Observing
• Collecting data
• Inferring
OBJECTIVES
• Observe anatomical structures of an echinoderm.
• Infer function of body parts from structure.
MATERIALS
• disposable gloves
• dissecting microscope
• preserved sea star
• forceps
• dissection tray
• blunt probe
• dissection scissors
• sharp probe
• hand lens
• dissection pins
SAFETY
CAUTION: Always wear safety goggles and a lab apron to
protect your eyes and clothing.
CAUTION: Do not touch or taste any chemicals. Know the location of the
emergency shower and eyewash station and how to use them. If you get
a chemical on your skin or clothing, wash it off at the sink while calling
to the teacher. Notify the teacher of a spill. Spills should be cleaned up
promptly, according to your teacher’s directions.
CAUTION: Glassware is fragile. Notify the teacher of broken glass or
cuts. Do not clean up broken glass or spills with broken glass unless
the teacher tells you to do so.
Before You Begin
Sea stars are members of the phylum Echinodermata, a group of invertebrates
that also includes sand dollars, sea urchins, and sea cucumbers. Echinoderms
share four main characteristics: an endoskeleton, five-part radial symmetry,
a water-vascular system, and circulation and respiration through their coelom.
1. Write a definition for each boldface term above. Use a separate sheet
of paper. Answers appear in the Teacher’s Notes.
2. You will be using the data table provided to record your data.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt Program
Science: Biology
Title
352
BiologyChapter
Video Labs
Title
TEACHER RESOURCE PAGE
Name
Class
Date
Analyzing Sea Star Anatomy continued
3. Based on the objectives for this lab, write a question you would like
to explore about sea star anatomy.
Answers will vary. For example: Which of the sea star’s body structures are
modified for feeding?
Procedure
PART A: EXTERNAL ANATOMY
1.
CAUTION: Put on safety goggles, a lab apron, and
protective gloves. As you observe the sea star body
structures, record your observations and your inference of each structure’s
function in the table. On a separate sheet of paper or in your lab notebook,
draw and label the sea star and the structures that you observe.
Data Table
Function of Sea Star Structures
Structure
Observations
Inferred function
Madreporite
Spine
Skin gill
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt Program
Science: Biology
Title
353
BiologyChapter
Video Labs
Title
TEACHER RESOURCE PAGE
Name
Class
Date
Analyzing Sea Star Anatomy continued
2. Using forceps, hold a preserved sea star under running water to gently but
thoroughly remove excess preservative. Then place the sea star in a dissecting tray.
3. Refer to a diagram of a sea star in your textbook to locate the madreporite on
the upper surface of the sea star.
4. Use a hand lens to observe the sea star’s spines. Are they distributed in any
recognizable pattern? Are they exposed or covered by tissue? Are they movable or fixed?
Spines are short, scattered over the surface, exposed, and fixed.
5. Use the dissecting microscope to look for small skin gills, If any are present,
describe their location and structure.
Skin gills are distributed between the spines but may not be visible
in preserved specimens.
6. Examine the sea star’s lower surface. Find the mouth, and use forceps or
a probe to gently move aside any soft tissues. What structures are found
around the mouth?
Five pairs of movable spines surround the mouth.
7. Locate the tube feet. Describe their distribution. Using a dissecting
microscope, observe and then draw a single tube foot on a separate sheet
of paper.
Tube feet are arranged in two rows along the length of each arm’s oral surface.
PART B: INTERNAL ANATOMY
8.
CAUTION: Scissors, probes, and pins are sharp. Use care not to
puncture your gloves or injure yourself or others. Using scissors
and forceps, carefully cut the body wall away from the upper surface of one
of the sea star’s arms. Start near the end of the arm and work toward the
center.
9. Find the digestive glands in the arm you have opened. Then, locate the short
branched tube that connects the digestive glands to the pyloric stomach.
10. Cut the tube that connects the digestive glands to the stomach, and move the
digestive glands out of the arm. Look for the reproductive organs.
11. Locate the two rows of ampullae that run the length of the arm.
12. Carefully remove the body wall from the upper surface of the central region
of the sea star. Locate the pyloric stomach and the cardiac stomach.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt Program
Science: Biology
Title
354
BiologyChapter
Video Labs
Title
TEACHER RESOURCE PAGE
Name
Class
Date
Analyzing Sea Star Anatomy continued
13. Remove the stomachs and find the ring canal and the radial canals. In which
direction does water move through these canals?
Water moves from the ring canal to the radial canals.
14.
Dispose of sea stars and sea star body parts in the waste container
designated by your teacher. Do not put lab materials in the trash unless
your teacher tells you to do so.
15.
Clean up your work area and all lab equipment. Return lab equipment to
its proper place. Wash your hands thoroughly before you leave the lab
and after you finish all work.
Analyze and Conclude
1. Analyzing Results What type of symmetry is found in the sea star?
Sea stars have five-part radial symmetry.
2. Inferring Relationships What is the relationship between the ampullae
and the tube feet?
The ampullae are hollow and are connected to the tube feet. The ampullae
pump water into the tube feet, causing the tube feet to expand outward.
3. Making Predictions How does a sea star use its stomach during feeding?
Part of the stomach is thrust through the mouth, and digestive juices liquefy
the prey, which then is ingested.
4. Making Predictions If the ring canals and radial canals did not function
properly, how would this affect the sea star’s ability to move and feed?
Because the sea star’s water-vascular system is essential to locomotion and
feeding, the sea star would not be able to move about or feed normally if the
ring canals and radial canals malfunctioned.
5. Further Inquiry Write a new question about echinoderms that could be
explored with another investigation.
Answers will vary. For example: How do the bodies of sea urchins differ from
those of sea stars?
Copyright © by Holt, Rinehart and Winston. All rights reserved.
Holt Program
Science: Biology
Title
355
BiologyChapter
Video Labs
Title