Question 84·Hard·Central Ideas and Details
While studying a newly discovered octopus species in 2021, marine biologists filmed more than a thousand individuals clustered on the seafloor around low-temperature hydrothermal vents. The finding surprised researchers because most octopus species are solitary and rarely congregate. The team noted that nearly every adult female in the cluster was brooding eggs that were in a more advanced developmental stage than eggs laid by the same species just a few meters away on colder substrate. The scientists propose that by occupying slightly warmer waters near the vents, the females accelerate the rate at which their eggs mature, potentially shortening the incubation period from an estimated five years to about two.
Based on the text, which choice best describes the scientists’ hypothesis about why the octopuses gather around the vents?
For hypothesis questions, go straight to the sentence with a claim marker like “propose,” “suggest,” or “hypothesize.” Restate the exact cause-and-effect relationship in your own words, then pick the option that matches it without changing the target (eggs vs. adults) or adding a different benefit (food, safety, stability) not stated in the text.
Hints
Locate the key sentence
Find the sentence where the researchers “propose” an explanation. That sentence states their hypothesis.
Track cause and effect
Identify what changes near the vents (environment) and what outcome the scientists connect to that change (egg development/incubation time).
Don’t swap in a different benefit
Be careful: some choices may mention plausible vent benefits (food, energy savings, stability) but the passage ties the gathering specifically to egg development rate.
Step-by-step Explanation
Understand what the question is asking
The question asks for the scientists’ hypothesis about why the octopuses gather around the vents. You should select the choice that restates the scientists’ proposed explanation.
Find where the hypothesis is stated
Look for a signal word like “propose.” The passage says the scientists propose that occupying slightly warmer waters near the vents causes the females’ eggs to mature faster, potentially shortening incubation from about five years to about two.
Extract the cause-and-effect relationship
From that sentence:
- Cause: females occupy slightly warmer water near vents.
- Effect: eggs develop faster, so the incubation/guarding time is shorter.
Match to the answer choice
Choose the option that states that vent warmth speeds embryonic development and reduces the time eggs must be guarded. That matches: “The warmth from the vents speeds up embryonic development, reducing the time the eggs must be guarded.”