How have crayfish and pill bugs adapted to freshwater and life on land?

Crayfish and pill bugs have evolved distinct physiological adaptations to thrive in their respective freshwater and terrestrial environments.

Freshwater Adaptation: Crayfish

As aquatic crustaceans, crayfish utilize gills for respiration, which are protected by their exoskeleton. Because they live in water with a lower salt concentration than their internal body fluids, they face a constant influx of water via osmosis and a loss of essential salts. To maintain homeostasis, they actively absorb salts through their gills and excrete large quantities of dilute urine to remove excess water.123

Terrestrial Adaptation: Pill Bugs

Pill bugs are terrestrial isopods that have adapted to life on land, where desiccation is a primary threat. Unlike many other terrestrial arthropods, they lack a waxy epicuticle to prevent water loss, which restricts them to damp environments such as leaf litter, soil, or areas under logs and stones. Their exoskeleton provides structural support and protection, and they have evolved the ability to roll into a ball when disturbed to further minimize exposure to the environment.4567