Hermit crab wood and stone are used by some species). The tip of the hermit crab's abdomen is adapted to clasp strongly onto the columella of the snail shell. Most hermit crabs are nocturnal. Hermit crabs can be divided into two groups: As hermit crabs grow, they require larger shells. Since suitable intact gastropod shells are sometimes a limited resource, vigorous competition often occurs among hermit crabs for shells. The availability of empty shells at any given place depends on the relative abundance of gastropods and hermit crabs, matched for size. An equally important issue is the population of organisms that prey
Spider wasp Spider wasp Wasps in the family Pompilidae are commonly called spider wasps or pompilid wasps. The family is cosmopolitan, with some 5,000 species in six subfamilies. All species are solitary, and most capture and paralyze prey, though members of the subfamily Ceropalinae are cleptoparasites of other pompilids, or ectoparasitoids of living spiders. In South America, species may be referred to colloquially as or , though these names can be generally applied to any very large stinging wasps. Furthermore, in some parts of Venezuela and Colombia, it is called , or "horse killers", while in Brazil some particular bigger and brighter