Biology/Natural History: When placed on a substratum, the isopod will reorient itself along the long axis of its substratum and if placed otherwise, it immediately reorients itself. I. resecata prefers to feed on algae such as Macrocystis, Pelagophycus porra, Eisenia arborea, Pterygophora californica, and Egregia laevigata, or on eelgrass (Zostera). These animals appear to be temperature and salinity sensitive. A temperature of 15 degress Celsius is an optimum temperature for I. resecata. If temperatures reach between 29 and 31 degrees Celsius, the animal will die. If the isopod is placed in fresh water it survives a little over an hour in comparison with 33 hours in 125% seawater. Development of these isopods is a bit unclear, but studies show that the general body form changes little during growth. Features such as segment number and setae number vary directly with size, each molt providing further change. The species blends in with the kelp or eelgrass that it is on, and can also swim well using its pleopods.