How do crustaceans respond to their environment?

Answer 1

Crustaceans use their antennae to discern changes in their environment. They can sense changes in water pressure with their antennae. They use these because their hard outer shell does not have any sensitive nerve endings.

Answer 2

I have a crayfish at home. I put it in my saltwater pond. It responded badly to the salt. The vast amount sodium in the water resulted in rather red rash and a bad case of diarrohea.