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) very decurved bills. Many species, including the rufous-breasted hermit, also use the heliconias for nesting, attaching their conical nest to the underside of one of the plant's broad leaves. The taxonomy of some groups has changed significantly in recent years. Apart from those issues discussed at "Phaethornis", a taxonomic problem occurs with the "Threnetes leucurus"/"T. niger" complex. Schuchmann & Hinkelmann (1999) considered the sooty barbthroat a melanistic variant of the "T. leucurus", but as it was described first, its scientific name was adopted for the entire species; pale-tailed barbthroat ("T. niger"). This, however, has not been accepted by all authorities,