Hermit crab shells instead, as shown by a specimen of "Palaeopagurus vandenengeli" from the Speeton Clay, Yorkshire, UK from the Lower Cretaceous. Hermit crab Hermit crabs are decapod crustaceans of the superfamily Paguroidea. Most of the approximately 1,110 species possess an asymmetrical abdomen that is concealed in a scavenged mollusc shell carried around by the hermit crab. Most species have long, spirally curved abdomens, which are soft, unlike the hard, calcified abdomens seen in related crustaceans. The vulnerable abdomen is protected from predators by a salvaged empty seashell carried by the hermit crab, into which its whole body can retract. Most frequently,
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)