The curious incident of the hermit crab and the gastropod

Abstract

Living space is a fundamental resource for the growth and survival of plants, marine, and terrestrial animals and even human beings. Of the variety of life that covert space, hermit crabs are unique in their motivation to find, defend and maintain gastropod shells as portable homes. The limited supply of empty shells in the environment, as well as a constant need to upgrade these resources as they grow, means that these charismatic crabs are always on the lookout for bigger, better and newer homes. We present the curious case of an intertidal hermit crab (Isocheles sawayai) that was found dead, tucked away behind the body of an injured gastropod (Olivancillaria vesica) whose shell it was presumably trying to occupy. This unusual observation highlights the extremes to which some crabs may go to beat potential rivals and be the first to access limiting resources.