Lab 3: Darien Rainforest Food Chain and Food Web
Week of Tue, Sep 15 · lab closes Mon, Sep 21 · 30 points
This lab's items
- Lab Write Up30 pts
Exact due times are in Canvas. Late assignments are not accepted without a valid, documented reason. Make-up assignments are not given without valid documentation.
Know these cold
- The Darien rainforest spans the border of Panama and Colombia. It contains one of the highest concentrations of biodiversity in the Western Hemisphere — jaguars, tapirs, harpy eagles, poison dart frogs, and hundreds of plant species interact in complex food webs.
- A food chain shows one path of energy transfer: producers → primary consumers → secondary consumers → tertiary consumers. A food web shows all interconnected chains at once, which is a far more accurate picture of an ecosystem.
- Producers (autotrophs) use photosynthesis to convert sunlight, CO₂, and water into glucose. In the Darien rainforest, producers include trees, epiphytes (air plants), bromeliads, and ground ferns.
- Primary consumers eat producers. In the Darien: tapirs, leaf-cutter ants, caterpillars, parrots, and howler monkeys. Secondary consumers eat primary consumers: ocelots, snakes, and bats. Tertiary (apex) consumers: jaguar, harpy eagle, black caiman.
- The 10% rule: only about 10% of energy stored at one trophic level transfers to the next. The other 90% is lost as metabolic heat. This is why food chains rarely exceed four or five levels.
- Trophic cascades occur when removing one species (especially a predator) triggers chain reactions throughout the food web. Remove the jaguar, deer populations explode, vegetation declines, smaller animals lose habitat.
- Conservation of the Darien is complicated by its remote geography and the proposed Darien Gap highway. Conservation biologists track keystone species (jaguar, harpy eagle) as indicators of food web integrity.
- When building a food web diagram, arrows show the direction of energy flow — they point FROM the organism being eaten TO the one eating it. Common mistake: drawing arrows toward the prey.
Discussion and forum — how to show up
Netiquette from the syllabus: address ideas, not people. Complete sentences, correct spelling. Personal matters go to email, never the board.
Meerk's quiz — open the Lab 3 gate
10 questions, no time limit. 85% on your first attempt in a 24-hour window opens the gate. Retakes inside the window are practice — they help you learn, they don't count. Work alone; the point is to know it, not to have seen it.
Dinner Table Question
Ask at home: If the top predator in a food web near you disappeared tomorrow, what chain of events do you think would follow over the next few years?
En español: Si el depredador tope de una red alimentaria cerca de ti desapareciera mañana, ¿qué cadena de eventos crees que seguiría en los próximos años?