Hermit crab on physical characteristics, genetic information, and combined data, support the longstanding hypothesis that the king crabs in the family Lithodidae are derived hermit crabs and should be classified as a family within Paguroidea. Other researchers have challenged this, asserting that the Lithodidae (king crabs) should be placed with the Hapalogastridae in a separate superfamily Lithodoidea. Six families are formally recognized in the superfamily Paguroidea, containing around 1100 species in total in 120 genera. The fossil record of "in situ" hermit crabs using gastropod shells stretches back to the Late Cretaceous. Before that time, at least some hermit crabs used ammonites'
Tapajós hermit little hermit, and the Tapajós hermit was believed to be most closely related to the black-throated hermit. In 1996 it was suggested that the Tapajós hermit was entirely invalid, and actually represented hybrids between the reddish and streak-throated hermits. In 2009 this hypothesis was shown to be incorrect, and the Tapajós hermit was instated as a valid species. Tapajós hermit The Tapajós hermit ("Phaethornis aethopygus") is a species of hummingbird in the family Trochilidae. It is found in the south-eastern Amazon in Brazil, and its common name refers to the Tapajós River, which forms the western border of its distribution.