Why would a normally aquatic or marine species adapt to the supralittoral fringe where they have to deal with desiccation and temperature stress?​

In order to survive.

Explanation:

A normally aquatic species adapt to the supralittoral fringe in order to survive in that environment. Supralittoral zone also referred to the area on coastlines and estuaries, that is regularly splashed, but not submerged by ocean water. This environment is different for the marine organisms that causes adverse effect on the marine organisms but these marine animals has the ability to adapt that environment by using certain mechanism in order to survive and easily reproduce in that environment.

the dark variety, as they are not visible on the dark tree barks

explanation: