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Survivorship Curves Comparator

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About This MicroSim

This interactive visualization displays the three classic survivorship curve types on a semi-logarithmic plot. Type I organisms (humans, elephants, whales) have high survival through most of their lifespan with rapid die-off in old age. Type II organisms (robins, squirrels, turtles) have a constant mortality rate at all ages. Type III organisms (oysters, oak trees, salmon) produce many offspring but most die very young. Students classify 9 organisms by dragging them to the correct curve type, with immediate feedback on each placement.

How to Use

  1. Read the chart — the semi-log plot shows the number of survivors (y-axis, log scale) versus the percentage of maximum lifespan (x-axis). Notice how the three curve shapes differ.
  2. Drag organisms from the pool on the right into the correct drop zone (Type I, II, or III).
  3. Check your answers — correct placements show green with a checkmark, incorrect show red with an X.
  4. Click "Hints" to see a brief clue about each organism's life history strategy.
  5. Hover over the curves to see exact survivor counts at any point in the lifespan.
  6. Click "Reset" to clear all placements and try again.

Lesson Plan

Grade Level

9-12 (college placement Biology)

Duration

10-15 minutes

Prerequisites

  • Understanding of population ecology basics
  • Knowledge of r-selected vs K-selected life history strategies
  • Familiarity with logarithmic scales

Activities

  1. Exploration (5 min): Examine the three curves without placing any organisms. At what percentage of maximum lifespan does each curve show the steepest decline? What does the slope of a survivorship curve represent biologically? (Answer: the age-specific mortality rate.)
  2. Guided Practice (5 min): Turn on Hints and classify all 9 organisms. For each one, explain why you chose that curve type. What reproductive strategy does each curve type correspond to? (Type I → K-selected, few offspring, high parental care; Type III → r-selected, many offspring, little care.)
  3. Assessment (5 min): Reset and classify without hints. Then answer: A species produces 10,000 eggs per year but only 2-3 survive to adulthood. Which curve type is this? If a new predator is introduced that kills adults equally at all ages, which curve type would the population shift toward?

Assessment

  • Can students correctly classify organisms into Type I, II, or III survivorship curves?
  • Can students explain what the shape of each curve indicates about mortality patterns?
  • Can students connect survivorship curves to r/K selection theory?
  • Can students predict how environmental changes would alter a species' survivorship curve?

References

  1. Survivorship curve - Wikipedia
  2. Life table - Wikipedia
  3. r/K selection theory - Wikipedia