What best describes the impact of the green crab on coastal habitats?

• A. Native predator of fish larvae
• B. Invasive, eats shellfish, erodes habitat
• C. Decomposer of organic debris
• D. Pollinator of marsh plants

Answer: (B)

Understanding the impact of an invasive species on coastal habitats helps explain why the green crab is such a problem. This crab is not native to many Atlantic coast ecosystems, and once established it acts as a strong predator on shellfish like clams, mussels, and oysters. Removing these shellfish from the community shifts the balance of species and food webs, often reducing biodiversity and altering how the habitat functions. In addition to predation, the crab’s burrowing and feeding activities disturb soft sediments and can erode habitat structure, especially in intertidal zones. All of this together—being invasive, feeding on shellfish, and causing physical habitat disruption—best describes its impact.

The other descriptions don’t fit because the green crab is not primarily a native fish larvae predator, it is not a decomposer, and it does not pollinate marsh plants.