Kelp Forest Lab: follow the connections.

Your learning goals

• Connect three organisms with feeding arrows and explain what each arrow means.
• Identify the change you make and distinguish it from the changes you observe later.
• Use two observations to explain an indirect effect, then name a limit of the evidence.

After your 3–2–1, take 2 minutes to add one evidence reflection: “I noticed ___; I can point to ___ in the image.” In a class, briefly compare observations with a partner if your teacher directs it. Working alone, reread your observations and choose the clearest visible detail. Keep your opening question for the conclusion.

Three organisms, two feeding links

Kelp is large marine algae. It uses sunlight to make food and forms habitat for other organisms. Sea urchins graze on kelp. Sea otters can eat sea urchins. A simple food chain is kelp → sea urchin → sea otter: each arrow points from food to the organism eating it, showing the direction of energy transfer.

An otter can affect kelp without eating it. If otters reduce grazing by urchins, kelp may benefit. A change that passes between feeding levels is called a trophic cascade. This is one pathway in a larger food web, not a claim that every otter eats only urchins or that every kelp forest behaves alike.

Use the lab’s Fab 5 cards for 3 minutes. In journal Section 2, define these terms in your own words and write one sentence connecting two of them:

Ecosystem

Organisms and their physical surroundings interacting in one place.

Producer

An organism that makes its own food; kelp does so using sunlight.

Consumer

An organism that gets energy by eating other organisms.

Predator

An animal that hunts and eats other animals.

Prey

An animal eaten by a predator. One organism can be both predator and prey in a larger web.

Science background: NOAA’s aquatic food webs guide.

Make a comparison you can explain

Plan for 2 minutes. In Section 1, state the purpose: investigate how removing otters may affect sea urchins and kelp. Write “If otters disappear, I predict ___ because ___.” Record your prediction before testing it; you can revise your explanation afterward.

Prepare for 2 minutes. Practice opening and closing a close-up. In Section 3, make three rows: “Otters removed,” “Time passes,” and “Otters return.” Beside each, leave space for what I did, what I observed, and what I think it means.

1. Begin with the starting forest. Note the visible otters, urchins, and kelp. This is your comparison point.
2. Select Remove the otters. Record what changed immediately and what has not changed yet. The starting change is whether otters are present.
3. Select Let time pass. Describe the seafloor in your journal before answering the activity’s question. Then use Watch what happens to kelp and record a visible detail before selecting a response. Compare your reasoning with the feedback.
4. Select Bring the otters back, then Let time pass. Separate the immediate change from the later result. Compare both organisms with your earlier notes.

Allow 11 minutes for this guided sequence. It illustrates the logic of changing one factor, but it is a programmed, qualitative model—not a controlled field experiment. There are no temperature sliders or population measurements. Describe trends rather than counting drawings as real organisms. Replaying the same sequence is not independent experimental evidence.

Turn your observations into an explanation

Draw for 10 minutes. In Section 4, divide a journal page into two panels labeled “With otters” and “Without otters.” Use the activity’s comparison buttons to inspect each scene. Sketch and label kelp, sea urchins, and sea otters; label an absent organism as absent. Add each organism’s feeding role and a short caption describing the difference you observed. Simple pencil outlines are enough. Draw the food-energy chain below the panels.

Analyze for 7 minutes. In Section 5, answer the lab’s three questions in your own words before opening each self-check:

• How could removing otters affect kelp even though otters do not eat kelp? Connect all three organisms and cite two observations.
• What did you change, and which outcomes did you observe later?
• Would returning otters guarantee the same recovery in every real forest? Name an omitted factor and explain why it matters.

Conclude for 3 minutes. In Section 6, explain the connections, compare the result with your prediction, and revisit your opening question. Identify any question the model cannot answer. Your finished report has six sections: exploration and prediction; vocabulary; procedure and observations; labeled drawings; analysis; and conclusion.

Why a real coastline may respond differently

Kelp also depends on physical conditions. Warm water, reduced light, storms, disease affecting predators, and other grazing animals can change the outcome. Other predators may eat urchins, and otters have other prey. These factors are not adjustable in this activity. Restoring one feeding link may help a forest, but does not guarantee recovery.

The scene’s illustrations are not field photographs or measured population data. “Let time pass” has no fixed number of days or years. The model does not calculate fish populations, rates of kelp growth, or a recovery deadline. A careful conclusion says what the model illustrates and what additional observations would be needed in nature.

Compare the model with NOAA’s kelp forest overview and Channel Islands National Park’s kelp forest account, which describe habitat, environmental pressures, and a wider community of organisms.