Which organism is commonly found in high-tide zones?

The correct answer, crabs, are commonly found in high-tide zones due to their adaptability to fluctuating conditions of salinity, temperature, and moisture levels. In these intertidal environments, crabs often seek shelter under rocks or within crevices to avoid desiccation during low tide and to protect themselves from predators. Their ability to move between different tidal zones allows them to take advantage of the varying food sources available as the tide rises and falls.

While other organisms such as sea stars, mussels, and oysters can be found in intertidal zones, they tend to occupy slightly different niches. Sea stars often inhabit lower intertidal zones and subtidal areas where they can access food more consistently, particularly in areas with more water coverage. Mussels and oysters usually adhere to hard substrates in the mid to lower tidal zones, where they can filter feed effectively. Thus, crabs' behavior and physiological adaptations make them particularly well-suited for the high-tide zone, where they can thrive amidst the challenges of this dynamic habitat.