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
Rufous-breasted hermit attached to the underside of a palm, fern or "Heliconia" leaf one or two meters (3–6 ft) above ground or so. The nests are often near a stream, waterfall or roadside, and are surprisingly easy to find. Incubation is 17 days with 23 more to fledging, and this species may nest up to four times in a season. The male of this aggressive and inquisitive hummingbird helps to build and defend the nest, but does not incubate the eggs. At least regionally (e.g. in Colombia), the species breeds all year. Rufous-breasted hermit The rufous-breasted hermit or hairy hermit ("Glaucis hirsutus")