1. This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

    This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

    • Scientific Accuracy
    • Alignment of Learning Goals, Activities, and Assessments
    • Pedagogic Effectiveness
    • Robustness (usability and dependability of all components)
    • Completeness of the ActivitySheet web page

    For more information about the peer review process itself, please see https://serc.carleton.edu/teachearth/activity_review.html.

This page first made public: Aug 12, 2008

Lab 2: Anatomy of Coral

The lab activity described here was created by Erin Bardar and LuAnn Dahlman of TERC for the EarthLabs project.

Summary and Learning Objectives

In this activity, students examine hydra, a fresh-water relative of coral, under a microscope to observe feeding behavior and identify stinging cells that are characteristic of corals. They also learn more about the individual animals that make up coral reefs and construct simple models of coral polyp anatomy and feeding behavior.

After completing this investigation, students will be able to:

  • draw conclusions about corals by examining the behavior of hydra;
  • explain and model how corals eat, grow, and reproduce; and
  • explain the difference between hard and soft corals.
Open the Student Lab »

Context for Use

Lab 2: Anatomy of Coral introduces students to anatomy/biology of the individual coral polyps that join together to form reefs. This activity should take approximately two 50-60 minute class periods. Part A is a hands-on wet lab that requires the advance purchase of hydra and daphnia or brine shrimp samples. In Part B, students compare the anatomy of hydra with that of coral polyps and construct a simple model of coral anatomy and processes using egg carton cups and other common craft materials.

Activity Overview and Teaching Materials

In Part A students take a close-up look at coral's freshwater cousin, the hydra. You will need the following materials for each student or small group of students:

  • hydra samples
  • medicine droppers
  • depression (well) slides
  • straight pins or paper clips
  • daphnia or brine shrimp
  • magnifying lenses
  • microscopes

In Part B of this lab, students make comparisons between the hydra anatomy they observed in Part A with a diagram showing the anatomy of a hard coral polyp. Students are then introduced to the difference between hard and soft corals and to zooxanthellae, the photosynthetic algae that provide corals with color and nutrition. Finally, students build simple physical models of coral polyps using egg carton cups and common craft supplies. Each student or small group of students will need:

  • 3" x 3" sticky notes (i.e. Post-It® notes)
  • pencils or pens
  • transparent tape
  • scissors
  • egg carton cups
  • additional craft supplies (i.e., markers, construction paper, glue, etc.)

Printable Materials

  • Activity Sheet (PDF (Acrobat (PDF) 26kB Apr1 08) and Word (Microsoft Word 2007 (.docx) 20kB Aug7 18))

Teaching Notes and Tips

Make sure students follow proper lab safety procedures and handle live specimens with care.

Collect polyp models for re-use later in the unit.


You can assess student understanding of topics addressed in this Investigation by grading their responses to the Stop and Think questions.

State and National Science Teaching Standards

California Science Teaching Standards met by this activity

Developer will correlate activity to standards in these documents:
Earth science content standards - Grades 9 to 12
Biology content standards (see Ecology) - Grades 9 to 12
Investigation and Experimentation Standards - Grades 9 to 12

Developer will correlate activity to standards in this document:

PDF of Science and technology standards Earth science standards begin on page 112

Developer will correlate activity to standards in this document:

Learning standards for science

Developer will correlate activity to standards in this document:

North Carolina Standard Course of Study

Developer will correlate activity to standards in this document:

Texas Essential Knowldege and Skills (TEKS)

Developer will correlate activity to standards listed at this site:

National Science Education Standards (SRI)

Additional Resources

Content Extension