July/August 2017 – Vol. 29 No. 8

Build a Coral Polyp

Posted: Monday, August 1st, 2011

Courtesy of the California Academy of Sciences


3rd – 5th Grade


Life Sciences


Ecological Relationships, Habitats & Ecosystems, Plant & Animal Structures


10 min Prep + 35 min Activity

Objectives: In this lesson, students will:

  1. learn the anatomy of a coral polyp.
  2. review the differences between plants and animals.
  3. earn about the unique symbiotic relationship between corals and zooxanthellae.


paper towels/rag for clean-up
plates (1 per student)
toothpicks (1 per student)
plastic straw (1 per student)
section of large banana (1 per student)
sour candy straws or twizzlers cut into 1 inch pieces (6 per student)
sugar sprinkles (same color as the sour candy straws or twizzlers)
round crackers (1 per student)
oyster crackers (5-6 per student)
transparency of coral polyp illustration
coral polyp worksheets (1 per student)
colored pencils, crayons, or markers


  • hard coral: marine animal that produces a hard, calcium carbonate skeleton and grows into coral reefs
  • coral polyp: a marine animal with a body shaped like a cylinder and tentacles around a central mouth
  • algae: a general term for microscopic or larger aquatic plants. They differ from trees and bushes because they don’t have true roots, stems, and leaves.
  • zooxanthellae: tiny algae that sometimes live inside other organisms such as coral
  • tentacles: a flexible body part that is used for feeding, grasping, or moving
  • predator: animals that eat other animals
  • symbiosis: a close relationship between two or more organisms of different species, which is often beneficial for one or both organisms


Corals are animals that belong to the phylum Cnidaria, which contains sea anemones, jellyfish, hydra, and corals. The name “Cnidaria” comes from the Greek word “cnidos” which means stinging nettle. Cnidarians are radially symmetrical with an opening at one end that is surrounded by tentacles. The tentacles have specialized stinging structures called nematocysts that are used for protection and to capture prey. The tentacles bring food into the animal’s one opening, which is used both to take in food and to expel waste materials. The coral animal, made up of its tube-shaped body, its tentacles, and its mouth, is called a coral polyp.

There are two main types of corals: hard corals and soft corals. Hard corals are classified within the subclass Hexacorallia because their tentacles are arranged around the mouth in multiples of six (“hexa” = six). They are called hard corals because they extract calcium and carbon from the ocean water and deposit a hard calcium carbonate skeleton that surrounds the lower portion of the body. Coral polyps fuse their skeletons together and form large coral colonies. These fused polyps are the basis for coral reefs. Coral polyps extend their tentacles from their skeleton to feed and withdraw into the skeleton for protection. Thus, the appearance of a coral colony can look very different depending on whether the polyps are extended or not. When hard coral polyps die, the calcium carbonate skeleton remains intact. You can often find pieces of white coral, the remains of former coral colonies, washed up on tropical beaches.

Soft corals are classified within the subclass Octocorallia because their tentacles are arranged around the mouth in multiples of eight (“octo” = eight). Soft corals do not produce a hard external calcium carbonate skeleton and therefore do not contribute significantly to the building of reefs. They do however have small, hard internal structures called spicules, which are uniquely shaped for each species and are used to help identify soft corals. When soft coral polyps die, they decompose and simply disappear, except for their small spicules.

Hard corals and some soft corals contain zooxanthellae within their tissue. Zooxanthellae are marine algae, some of which are free living and some of which live inside the translucent, fleshy tissue of many corals and other marine organisms. Zooxanthellae that live in marine animals have a mutually beneficial symbiotic relationship with their host. This means that both the coral and the alga benefit from being in the relationship. The zooxanthellae photosynthesize from within their coral host and produce sugars that provide nutrition to both the zooxanthellae and the coral. In return, the coral provides protection and assists the growth of the zooxanthellae by passing on some of its waste, which the zooxanthellae use as a nutrient source. It is the colorful zooxanthellae that give coral their different colors and because zooxanthellae need sunlight to perform photosynthesis, they are the reason why corals need sunshine to survive.

If coral is affected by an environmental stress such as increased temperature or sedimentation, the zooxanthellae leave the coral and the coral turns white. This is termed coral bleaching. Although zooxanthellae can live freely in the water without coral, corals that normally contain zooxanthellae in their tissue cannot survive for long without their symbiotic algae. They will slowly starve. Thus, coral bleaching can be lethal for the coral if the coral polyps do not reacquire zooxanthellae. The phenomenon of coral bleaching is of particular concern as sea surface temperatures rise with human-induced climate change.



  1. Set out enough plates for each student to have one.
  2. On each plate, place…
  • 1 piece banana
  • 1 toothpick
  • 1 straw
  • six candy straws/twizzlers
  • small pile of sprinkles
  • 6-8 oyster crackers
  • 1 round cracker
  • small amount of jam


  1. Ask students, “How many of you think coral is a plant? How many of you think coral is an animal?”
  2. Corals are animals! Go over some of the big differences between plants and animals. Make a table on the board.
  3. Plants Animals
    Plants use the sun’s energy to make food through a process known asphotosynthesis. Animals cannot produce their own food from the sun and must eat other organisms in order to get food and energy.
    Only plants have roots, stems and leaves. Animals do not have roots, stems and leaves.
    Plants generally do not move from one place to another. Animals generally can move to catch food.
    Plants have chlorophyll in their cells to capture light energy. Animals do not have chlorophyll in their cells.
    Plant cells have walls. Animal cells don’t have walls and their cells are more flexible and variable in shape.
  4. Ask students, “What makes this coral polyp an animal?” (It eats other organisms by capturing them with its tentacles. It does not have plant parts. It cannot make food from the sun’s energy without the help of zooxanthellae.)
  5. Tell students they are going to do a very cool activity: make an edible coral polyp.
  6. Hand out one plate of materials to each student.

Directions for Making a Coral Polyp

Make a hole (the mouth) in the top half of the banana with a straw. Be careful not to go all the way through the banana as coral polyps have one hole, not two.

Create six holes with a toothpick surrounding the central mouth.

Poke 6 candy straws or twizzlers (the tentacles) into the holes.

Add sprinkles (zooxanthellae) to the banana.

Add round cracker and jam (coral is attached to the substrate).

Add oyster crackers around the base (calcium carbonate skeleton).

Students can place individual coral polyps together to form a colony.


  • Hand out one coral polyp worksheet to each student.
  • Students draw their coral polyp and answer the questions on the worksheet.
  • Remind students that there are a lot of different animals that live on reefs. People sometimes call coral reefs the “rainforests of the ocean” because there are so many different animals there just like in the rainforests.
  • Tell students they can pretend to be predatory fish, such as parrotfish, that eat coral. Students can eat their polyps, but since fish don’t have hands encourage your students to eat without using their hands.

Discuss coral reef threats and conservation with your students.

  • Explain that coral reefs are in danger of disappearing because of changes that people are making to the oceans.
  • What do you think people are doing to change the reefs? (fishing too much, polluting, physically damaging the reef by taking coral or anchoring on top of coral, breaking off coral while swimming, taking coral for jewelry, developing coastal areas which can cause increased sediment in the water and smother coral, and climate change is making the water too warm and too acidic)
  • What can we do? (Reduce, reuse, and recycle to help stop pollution, don’t get too close to reefs, don’t buy coral jewelry, reduce fossil fuel emissions associated with climate change, and help spread the word to friends and family).


Adapted from:

1. Ayres, R. California Academy of Sciences. Coral Polyp Party.

2. California Academy of Sciences’ Educator Resource Materials. (2007). Coral Symbiosis: Coral Polyp and Zooxanthellae.

University of California Museum of Paleontology, Taxon Lift. Introduction to Cnidaria. Retrieved April 28, 2008 from http://www.ucmp.berkeley.edu/help/taxaform.html

Correlated California State Content Standards

Grade Three
Life Sciences
3a. Students know plants and animals have structures that serve different functions in growth, survival, and reproduction.
3b. Students know examples of diverse life forms in different environments, such as oceans, deserts, tundra, forests, grasslands, and wetlands.

Grade Four
Life Sciences
2b. Students know producers and consumers are related in food chains and food webs and may compete with each other for resources.
3a. Students know ecosystems can be characterized by their living and nonliving components.

Source: http://www.calacademy.org/teachers/resources/lessons/build-a-coral-polyp/

Written by California Science Teachers Association

California Science Teachers Association

CSTA represents science educators statewide—in every science discipline at every grade level, Kindergarten through University.

2 Responses

  1. Although our images show sour candy for the polyp’s tentacles, here at the Academy, we often buy a bag of the long, red Twizzlers, which conveniently are made with 6 smaller strings of licorice. All you have to do is chop up the long, think Twizzler into 1-2 inch segments and you have a packet of tentacles to hand to students!



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CTC Seeking Educators for Science Standard Setting Conference

Posted: Wednesday, August 16th, 2017

The Commission on Teacher Credentialing (CTC) and Evaluation Systems group of Pearson are currently seeking California science educators to participate in a Science Standard Setting Conference for the California Subject Examinations for Teachers (CSET) program. Each standard setting panel is scheduled to meet for one-day, in Sacramento, California. The fields and dates are listed below:

Multiple Subjects Subtest II (Science), Monday, October 2, 2017
Science Subtest II: Physics, Monday, October 2, 2017
Science Subtest II: Chemistry, Tuesday, October 3, 2017
Science Subtest II: Life Sciences, Wednesday, October 4, 2017
Science Subtest II: Earth and Space Sciences, Thursday, October 5, 2017
Science Subtest I: General Science, Friday, October 6, 2017

The purpose of the conference is for panel members to make recommendations that will be used, in part, by the Commission on Teacher Credentialing (CTC) in setting the passing standard, for each field, in support of the updated California Subject Examinations for Teachers (CSET).

Click here to nominate educators. If you are interested in participating yourself, complete an application here for consideration.


Public school educators who are:

• Certified in California
• Currently practicing (or have practiced within the last school year) in one or more of the fields listed above. 

College faculty who are:

• Teacher preparation personnel (including education faculty and arts and sciences faculty)
• Practicing (or have practiced within the last school year) in one or more of the fields listed above, and
• Preparing teacher candidates in an approved California teacher preparation program.

 Benefits of Participation Include:
• Receive substitute reimbursement for their school (public school educators only),
• Have the opportunity to make a difference in California teacher development and performance,
• Have the opportunity for professional growth and collaboration with educators in their field,
• Be reimbursed for their travel and meal expenses, and
• Be provided with hotel accommodations, if necessary.

For more information, visit their website at www.carecruit.nesinc.com/cset/index.asp

Written by California Science Teachers Association

California Science Teachers Association

CSTA represents science educators statewide—in every science discipline at every grade level, Kindergarten through University.

CSTA Annual Conference Early Bird Rates End July 14

Posted: Wednesday, July 12th, 2017

by Jessica Sawko

Teachers engaged in workshop activity

Teachers engaging in hands-on learning during a workshop at the 2016 CSTA conference.

Don’t miss your chance to register at the early bird rate for the 2017 CSTA Conference – the early-bird rate closes July 14. Need ideas on how to secure funding for your participation? Visit our website for suggestions, a budget planning tool, and downloadable justification letter to share with your admin. Want to take advantage of the early rate – but know your district will pay eventually? Register online today and CSTA will reimburse you when we receive payment from your district/employer. (For more information on how that works contact Zi Stair in the office for details – 916-979-7004 or zi@cascience.org.)

New Information Now Available On-line:

Written by California Science Teachers Association

California Science Teachers Association

CSTA represents science educators statewide—in every science discipline at every grade level, Kindergarten through University.

Goodbye Outgoing and Welcome Incoming CSTA Board Members

Posted: Wednesday, July 12th, 2017

Jill Grace

Jill Grace, CSTA President, 2017-2019

On July 1, 2017 five CSTA members concluded their service and four new board members joined the ranks of the CSTA Board of Directors. CSTA is so grateful for all the volunteer board of directors who contribute hours upon hours of time and energy to advance the work of the association. At the June 3 board meeting, CSTA was able to say goodbye to the outgoing board members and welcome the incoming members.

This new year also brings with it a new president for CSTA. As of July 1, 2017 Jill Grace is the president of the California Science Teachers Association. Jill is a graduate of California State University, Long Beach, a former middle school science teacher, and is currently a Regional Director with the K-12 Alliance @ WestEd where she works with California NGSS K-8 Early Implementation Initiative districts and charter networks in the San Diego area.

Outgoing Board Members

  • Laura Henriques (President-Elect: 2011 – 2013, President: 2013 – 2015, Past President: 2015 – 2017)
  • Valerie Joyner (Region 1 Director: 2009 – 2013, Primary Director: 2013 – 2017)
  • Mary Whaley (Informal Science Education Director: 2013 – 2017)
  • Sue Campbell (Middle School/Jr. High Director: 2015 – 2017)
  • Marcus Tessier (2-Year College Director: 2015 – 2017)

Learn More…

Written by California Science Teachers Association

California Science Teachers Association

CSTA represents science educators statewide—in every science discipline at every grade level, Kindergarten through University.

Finding My Student’s Motivation of Learning Through Engineering Tasks

Posted: Wednesday, July 12th, 2017

by Huda Ali Gubary and Susheela Nath

It’s 8:02 and the bell rings. My students’ walk in and pick up an entry ticket based on yesterday’s lesson and homework. My countdown starts for students to begin…3, 2, 1. Ten students are on task and diligently completing the work, twenty are off task with behaviors ranging from talking up a storm with their neighbors to silently staring off into space. This was the start of my classes, more often than not. My students rarely showed the enthusiasm for a class that I had eagerly prepared for. I spent so much time searching for ways to get my students excited about the concepts they were learning. I wanted them to feel a connection to the lessons and come into my class motivated about what they were going to learn next. I would ask myself how I could make my class memorable where the kids were in the driver’s seat of learning. Incorporating engineering made this possible. Learn More…

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Written by NGSS Early Implementer

NGSS Early Implementer

In 2015 CSTA began to publish a series of articles written by teachers participating in the California NGSS k-8 Early Implementation Initiative. This article was written by an educator(s) participating in the initiative. CSTA thanks them for their contributions and for sharing their experience with the science teaching community.

State Schools Chief Tom Torlakson Unveils Updated Recommended Literature List

Posted: Wednesday, July 12th, 2017

SACRAMENTO—State Superintendent of Public Instruction Tom Torlakson unveiled an addition of 285 award-winning titles to the Recommended Literature: Prekindergarten Through Grade Twelve list.

“The books our students read help broaden their perspectives, enhance their knowledge, and fire their imaginations,” Torlakson said. “The addition of these award-winning titles represents the state’s continued commitment to the interests and engagement of California’s young readers.”

The Recommended Literature: Prekindergarten Through Grade Twelve list is a collection of more than 8,000 titles of recommended reading for children and adolescents. Reflecting contemporary and classic titles, including California authors, this online list provides an exciting range of literature that students should be reading at school and for pleasure. Works include fiction, nonfiction, poetry, and drama to provide for a variety of tastes, interests, and abilities. Learn More…

Written by Guest Contributor

From time to time CSTA receives contributions from guest contributors. The opinions and views expressed by these contributors are not necessarily those of CSTA. By publishing these articles CSTA does not make any endorsements or statements of support of the author or their contribution, either explicit or implicit. All links to outside sources are subject to CSTA’s Disclaimer Policy: http://www.classroomscience.org/disclaimer.