[Campbell Biology P.1199] Explain why, according to the optimal foraging model and the provid... | Practice Question

Explain why, according to the optimal foraging model and the provided graph, a drop height of 5 meters is considered more efficient results in lower total 'flight' height for breaking whelks compared to heights of 2 or 15 meters.

  • A: At 2 meters, the whelk is too light to break, and at 15 meters, the crow is too tired to drop it effectively.
  • B: At 2 meters, the lower drop height requires a significantly higher number of drops to break the whelk, making the cumulative flight energy (total flight height) very high. At 15 meters, while fewer drops are needed, the initial energy cost of flying to such a great height for each drop becomes excessively high, leading to a high total flight height. 5 meters represents the optimal trade-off.
  • C: The whelks are naturally weaker at 5 meters, requiring fewer drops and thus less energy from the crow.
  • D: Crows inherently prefer 5 meters for aesthetic reasons, independent of energy efficiency.

Explanation

The optimal foraging hypothesis suggests that animals aim to maximize energy gain while minimizing energy expenditure. The graph illustrates this trade-off: at lower heights e.g., 2m , a whelk requires many more drops to break high orange bar , leading to a high total cumulative flight energy high green bar . At very high heights e.g., 15m , even though fewer drops might be needed, the energy cost of flying to such a great height for each drop is so substantial that the total flight height remains very high. The 5-meter mark represents a sweet spot where the number of drops is sufficiently low, and the height per drop is not excessively high, resulting in the minimum total 'flight' energy required to break the whelk. This makes it the most energetically efficient height.