Certain species of isopods occur in a vertical series of shore habitats suggestive of a transition from marine to terrestrial life. The five species involved in this study exhibit structural, behavioral and physiological adaptations to the various levels which they occupy in the transition.
In general the more terrestrial isopods are heavily chitinized and the exopodites of the pleopods form a thick, protective covering for the endopodites. The thoracic appendages and general body form of the various species facilitate survival in the different environments by adhering to a basic theme of desiccation prevention.
Physiologically, the tolerances of the different species to variations in humidity and salinity corellate with the particular habitat involved and illustrate adaptations to the situations in which each species is found.