Corals are sessile, which means that they permanently attach themselves to the ocean floor, essentially “taking root” like most plants do. Corals actually comprise an ancient and unique partnership, called symbiosis, that benefits both animal and plant life in the ocean.
Corals have tiny, tentacle-like arms that they used to capture their food from the water and sweep into their inscrutable mouths. Because of this cycle of growth, death, and regeneration among individual polyps, many coral colonies can live for a very long time.
More than merely a clever collaboration that has endured between some of the tiniest ocean animals and plants for some 25 million years, this mutual exchange is the reason why coral reefs are the largest structures of biological origin on Earth, and rival old-growth forests in the longevity of their ecological communities. A coral polyp is an invertebrate that can be no bigger than a pinhead to up to a foot in diameter.
Each polyp has a saclike body and a mouth that is encircled by stinging tentacles. The polyp uses calcium carbonate (limestone) from seawater to build a hard, cup-shaped skeleton.
Coral reefs are marine structures made up of tiny animals called polyps. Successive layer of living polyps form, over time, enormous reef structures.
These limestone structures provides the habitat for a great variety of marine animal and plant species. They possess a set of tentacles that they used to catch their food from water and put it into a central opening or mouth.
The rate at which calcium carbonate is deposited on the reef structure varies from 0.3 to 2 centimeters every year. The coral provides the microalgae with a protective shell from the ocean environment and also the necessary compounds, such as carbon dioxide and nutrients for photosynthesis.
Corals may regain zooxanthellae back if the stressor is suppressed within short periods of time. Coral reefs support a great diversity of animal and plant species.
Most coral reefs are found in the tropical latitudes of the world 30 ° north or south of the equator. however, coral reefs have been found in Bermuda, 32 ° north of the equator, due that it is in the path of the Gulf Stream’s warming water currents.
Corals can also form on colder, deeper, darker waters, although, their capacity to produce calcium carbonate is greatly reduced. Coral reefs are sometimes referred to as the rainforests of the sea for the great diversity of marine animal and plant species that thrive in their ecosystem.
Algae: a general term for microscopic or larger aquatic plant-like organisms. They differ from trees and bushes because they don't have true roots, stems, and leaves.
Make copies of the Coral Polyp handout and the Analogy Map worksheet (1 per student). Each student will be working individually to build a coral polyp, but they should also be seated in groups of four or five to share some materials.
Give students some time (~1 minute) to brainstorm a short list of some key differences between plants and animals. Ask students to share some big differences between plants and animals.
Create a table on the board to keep track of the key differences between plants and animals. Explain that they are going to make a simple representation of coral polyp using everyday materials.
The TEACHER GUIDE shows what to draw on the board while students build their polyp. You can reassure students that they will get a chance to consume their coral polyps at the end of the lesson.
Begin the lesson by reminding students of the ideas that they discussed in Part 1. Once students have finished assembling their coral colonies, draw their attention back to the guiding question.
Give students time (~5 min) to think-pair-share on the question, based on what they learned from building their polyp. Tell students they can pretend to be predatory fish, such as parrot fish, that eat coral polyps.
GNSS SCIENCE AND ENGINEERING PRACTICES CONNECTION: This portion of the lesson connects to the Practice of Constructing Explanations because students are asked to explain why they think coral is a plant, animal, or something else. Students' explanations should come from the observations they made while building the representation of a coral polyp, and from the plant vs. animal brainstorm in Part 1.
Have students share their ideas about what the representation accurately shows (the basic parts of a coral polyp's anatomy) and what it doesn't show accurately (cellular structures, how corals move to catch food). Tell students that they will be making observations of coral in the real world to help deepen their ideas.
Play the Coral Seas episode on the Blue Planet DVD from 0:00-10:24. Teacher Tip: You can pause the video at 7:16, 7:18, and 8:43 to see some really great, close up views of polyps.
In small groups, have students discuss the ideas that are generated by this question. Tell students they will organize their reflections about their coral polyps using a tool called an Analogy Map.
Explain the parts of the Analogy Map, and give one copy of the worksheet to each student. The name “Cnidaria” comes from the Greek word “UNIDO” which means stinging nettle.
The tentacles have specialized stinging structures called nematocysts that are used for protection and to capture prey. Hard corals are classified within the subclass Hexacorallia because their tentacles are arranged around the mouth in multiples of six (hex = 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. When hard coral polyps die, the calcium carbonate skeleton remains intact.
Soft corals are classified within the subclass Octocorallia because their tentacles are arranged around the mouth in multiples of eight (onto = eight). Soft corals do not produce a hard external calcium carbonate skeleton and therefore do not contribute significantly to the building of reefs.
Zooxanthellae that live inside corals have a mutually beneficial symbiotic relationship with their host. Because zooxanthellae need sunlight to perform photosynthesis, they are the reason why corals need sunshine to survive.
K-2: Make observations (firsthand or from media) to construct an evidence-based account for natural phenomena. 3-5: Use evidence (e.g., measurements, observations, patterns) to construct or support an explanation.
Different animals use their body parts in different ways to see, hear, grasp objects, protect themselves, move from place to place, and seek, find, and take in food, water and air. Plants also have different parts (roots, stems, leaves, flowers, fruits) that help them survive and grow.
Plants and animals have both internal and external structures that serve various functions in growth, survival, behavior, and reproduction. Remember, performance expectations are not a set of instructional or assessment tasks.
This activity or unit is just one of many that could help prepare your students to perform the following hypothetical tasks that demonstrate their understanding: 4-LS1-1 Construct an argument that plants and animals have internal and external structures that function to support survival, growth, behavior, and reproduction.
Patrol multimedia is a hardy plant that thrives in nearly any lighting condition and grows like a weed. Sadly, this plant is tropical and suitable for United States Department of Agriculture zones 10 to 12 only.
Atrophy multimedia is also called Guatemala rhubarb and, more commonly, coral plant. Like all members of the family, Atrophy exudes latex sap, which is milky to opaque.
This is a frost sensitive specimen which can be killed if temperatures drop below 40 degrees Fahrenheit (4 C.). The upper surface of the leaf is dark green, but the undersides display a whitish cast.
Atrophy Matilda requires moderately fertile soil with excellent drainage. It has some drought tolerance once established but performs best with regular watering in a full sun situation.
In cool zones, plant the specimen in a large container with a gritty houseplant soil. Overly wet plants and those that receive splashed mud on the foliage may experience root rot or leaf spot.
Common pests include mealybugs, aphids, and scale, whose widespread feeding can diminish plant vigor and destroy the attractive leaves. It will release nutrients over 3 months to buoy spring growth and the formation of the brilliant pink flowers.
The huge plant, shockingly bright flowers, and delicate leaves provide enough incentive for any effort expended by the gardener.