What Are Corals?
OverviewStudents will learn that corals are living animals. They will be introduced to some of the species that make up the biodiversity in coral reefs, and why coral reefs are an important habitat. This lesson will serve as a brief overview of coral anatomy, distribution, its physical properties, and why it is important to conserve coral reefs.
Students will be able to:
1. Define the vocabulary term coral.
2. Identify and explain the role of corals in American Samoa's marine ecosystem.
3. Understand that corals are living animals.
Corals consist of small, colonial, plankton-eating invertebrate animals called polyps, which are anemone-like. Although corals are mistaken for non-living things, they are live animals. Corals are considered living animals because they fit into the five criteria that define them (1. Multicellular; 2. Consumes other organisms for food; 3. Has an internal digestive system; and 4. Embryonic development; 5. Motile, or can move independently).
The islands of American Samoa are blessed with an abundance of over 250 species of corals. Corals are animals like ourselves, although that they may not be readily apparent because many look like rocks, especially those washed up on the beach. In a sense, corals are indeed partly rock, because only the outer thin layer of the coral is inhabited by the coral animal itself. In that way, corals are like large trees – the inner part is hard and provides structural support, the outer part is the living, growing organism. And, like trees, most coral animals are permanently attached to one spot on the reef.
The coral rubble that Samoans traditionally spread outside their houses, and the coral rocks along our beaches, are old, dead pieces that broke off the reef during storms and got tumbled around and tossed up on the beach.
Coral reefs are complex structures built by coral organisms and algae that occur in shallow tropical waters. Living corals grow primarily on the outer reef flat and in deeper water. Although they take varied shapes, the coral animals inhabiting their surfaces are similar. They look somewhat like miniature sea anemones (matamalu, ulumane) or upside-down jellyfish (alualu) with short tentacles that give the coral a slightly fuzzy appearance when the tentacles are extended. Each single coral animal is called a polyp, but the coral branch or block we see on the reef is actually not a single animal but a colony of hundreds or thousands of tiny polyps living side by side, giving the appearance of a single coral. The coral's short tentacles can be pulled back into the hard part of the coral when the animal is disturbed or when the coral is exposed at low tide, so even a live coral can look like a rock at such times.
Corals feed on plankton that includes tiny crustaceans, mollusks, and larvae of reef animals. Corals use their tentacles or arms to sting and capture plankton that drifts by on currents. Shallow-water corals grow the fastest and are called reef building corals because they secrete skeletons of calcium carbonate, which construct large structures called coral reefs. The reef-building corals that form coral reefs in American Samoa are made up of several types of coral such as finger coral, staghorn coral, encrusting coral, flower coral, table coral, and mushroom coral. The adapted coral forms provide a prime habitat to marine organisms by providing protection and food resources. Coral reefs are important to conserve in American Samoa for the preservation of the corals themselves and especially for the conservation of the marine organisms that depend on coral reefs to survive.
1. Power point program
2. Blank poster boards
3. Markers and/or crayons
4. Recycled magazines
5. White paper plates
6. Synthetic feathers
Introduce Inquiry Question?
What are corals?
Ask: Has anyone seen coral? If yes, when and where did you see it? If not, what do you think it is? Explain that corals are a hard stony substance secreted by certain marine invertebrate animals that includes jellyfishes, corals, and sea anemones as an external skeleton, typically forming large reefs in warm oceans. Tell students the number of coral species in American Samoa. Talk about coral habitats and Zooxanthellae. Show them slides of healthy corals using the powerpoint program.
Split the class in two and have each group form a line (Line 1 and Line 2). Have students in Line 1 and Line 2 face each other. In consecutive order, allow them 30 seconds to talk about each of the following:1. Have students in Line 1 look across from them and ask their first partner in Line 2 where they have seen corals.
2. Shift both lines so every student moves to their left. If a student reaches the front of the line, have them move to the other end. Have student in Line 2 ask their new partner in Line 1 where they have seen corals.
3. Have both lines shift to the left again. Have the Line 1 person ask their new partner in Line 2 what they know about corals.
4. Have both lines shift to the left again. Have the Line 2 person ask their new partner in Line 1 what they already know about corals.
5. Have both lines shift to the left again. Have the Line 2 person ask their new partner in Line 1 what they already know about corals.
6. Have both lines shift left again. Have the Line 1 person ask their new partner in Line 2 what they want to know about corals.
7. Have both lines shift left again. Have the Line 2 person ask their new partner what they want to know about corals.
Group Discussion Activity:
Have students gather in a circle on the floor. Ask each student to tell the class what their partners said. Allow time for discussion.
1. Where did your partner see corals?
2. What does your partner know about corals?
Activity 2: Make your own coral
Have students arrange their desks and provide materials as indicated so that they may create their own corals.First, distribute a set of white paper plates to each student. Explain that the white paper plates represent their corals and that they have to use materials like crayons, markers, feathers, or any other recycled materials to decorate it. Tell students to be creative – that all corals come in different colors, shapes, and sizes.
Have students discuss their coral creations. Have student take turns sharing about their coral creations and describe the role it plays in the ocean ecosystem.
Conclusion with Inquiry Question
What are corals?
Encourage your family and friends to protect our coral reefs by doing the following:
1. Do not walk on corals
2. Put trash in bins to keep our ocean clean