Hermit crab gives rise to the popular name "hermit crab", by analogy to a hermit who lives alone. Several hermit crab species, both terrestrial and marine, have been observed forming a vacancy chain to exchange shells. When an individual crab finds a new empty shell it will leave its own shell and inspect the vacant shell for size. If the shell is found to be too large, the crab goes back to its own shell and then waits by the vacant shell for up to 8 hours. As new crabs arrive they also inspect the shell and, if it is too big,
Hermit (hummingbird) dimorphism usually associated with hummingbirds; green hermit is an exception to this rule. Hermits in the type genus, "Phaethornis", have a long decurved bill (three species, "P. koepkeae", "P. philippii" and "P. bourcieri", with virtually straight bills) with a red or yellow base to the lower mandible, and their two central tail feathers are elongated and tipped with white, buff or ochre. The crown of the head is flat, and two pale facial stripes enclose a dusky mask. Most hermits are restricted to the edge and undergrowth of forest, woodland and second growth, but some species (e.g. the planalto hermit)