Digital SATReading and Writing: Information and IdeasHard
A marine biologist is studying coral reef ecosystems. She observes that a particular species of fish, *Chromis viridis*, consistently exhibits schooling behavior in open water but disperses and seeks shelter among coral branches when a predatory shark, *Carcharhinus amblyrhynchos*, is sighted. When a non-predatory herbivorous shark, *Rhincodon typus*, is observed, the *Chromis viridis* maintain their schooling behavior. The biologist hypothesizes that the schooling behavior of *Chromis viridis* serves as a primary defense mechanism against specific threats, rather than a general social behavior. Which of the following observations would most strongly support the biologist's hypothesis?
- AOther species of reef fish also exhibit schooling behavior when predators are present.
- BThe *Chromis viridis* population size remains stable even with regular *Carcharhinus amblyrhynchos* sightings.
- CThe *Chromis viridis* fish species is known to have a complex social hierarchy within its schools.
- DIndividual *Chromis viridis* that stray from the school in the presence of *Carcharhinus amblyrhynchos* are significantly more likely to be preyed upon.
Show answer & explanationAnswer & explanation
Correct answer: D. Individual *Chromis viridis* that stray from the school in the presence of *Carcharhinus amblyrhynchos* are significantly more likely to be preyed upon.
The hypothesis is that schooling is a 'primary defense mechanism against specific threats.' If individuals outside the school are 'significantly more likely to be preyed upon' specifically by the predatory shark, it directly demonstrates the defensive benefit of schooling against that threat, thus strongly supporting the hypothesis.
Why the other options are wrong
- A. This shows schooling is a common defensive strategy but doesn't specifically support why *Chromis viridis* does it, or that it's a *primary* defense mechanism for *this* species.
- B. Population stability doesn't directly prove schooling is the *primary defense mechanism*; other factors could contribute to stability.
- C. This suggests schooling is a 'general social behavior,' which the hypothesis explicitly states it is *not* primarily, hence it weakens or is irrelevant.
Supporting a Hypothesis
Identifying evidence that increases the probability or credibility of a proposed explanation for an observation or phenomenon.
- Evidence must directly relate to the hypothesis's core claim.
- Strong support often demonstrates a cause-and-effect relationship.
- Must be distinguishable from merely consistent or irrelevant information.
Memory trick: Hypothesis, Harmony, Hit: Does the evidence 'H'elp the claim?