Sea urchin
"Z. adamsii" lives in symbiosis with a sea urchin, living among its spines. Sea urchins on which it has been found include "Asthenosoma ijimai", "Diadema setosum", "Heliocidaris crassispina", "Pseudocentrotus depressus", "Salmacis bicolor", "Salmacis virgulata", "Toxopneustes elegans", "Toxopneustes pileolus", "Tripneustes gratilla" and a species of "Acanthocidaris". Adaptations for this lifestyle include a specialist joint between the propodus and dactylus on the walking legs enabling the crab to cling to its host, and cryptic colouring in the form of vertical stripes. Females are slightly larger than males and usually live singly on a sea urchin while males move from one urchin to another searching for females.