What hypothesis did Garza and Robles propose regarding ochre sea stars after heavy rains?

• A. They hypothesized rainfall increases sea star reproduction.
• B. They hypothesized that a layer of fresh water formed by rainfall was a barrier to the sea stars.
• C. They hypothesized sea stars moved onto land after rain.
• D. They hypothesized rainfall had no effect on sea stars.

Answer: (B)

The question tests how a physical change in the environment can affect where marine animals can go. Garza and Robles proposed that a layer of fresh water formed by rainfall sits on the surface and acts like a barrier to ochre sea stars. Sea stars are adapted to saltwater, and crossing from saline water into a freshwater layer—or staying on the other side of that barrier—creates osmotic stress and movement difficulties for them. So, the freshwater layer would prevent the sea stars from moving across to deeper or differently salinated water, explaining their behavior after heavy rains. This idea hinges on salinity differences shaping where these intertidal organisms can travel and survive.