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
Straight-billed hermit Straight-billed hermit The straight-billed hermit ("Phaethornis bourcieri") is a species of bird in the family Trochilidae, the hummingbirds. It is found in the Guyanas of Guyana, Suriname, and French Guiana; also the northern Amazon basin of Brazil, and Amazonian Colombia, Ecuador, and Peru; it is in eastern Venezuela and the Orinoco River Basin. Its natural habitats are subtropical or tropical moist lowland forest and subtropical or tropical moist montane forest. Two subspecies are currently recognised: "P. b. bourcieri" and "P. b. major". However, recent molecular analysis has shown that "P. b. major" is more closely related to "Phaethornis philippii" and