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,
Nephilengys upon by the spider-eating jumping spider "Portia". At least some species shake their bodies vigorously when touched. Nephilengys Nephilengys is a genus of tropical spiders of the family Araneidae, consisting of two currently described species. (The genus was formerly placed in the Nephilidae and Tetragnathidae.) The genus "Nephilingis" has been split off from this genus. Both genera have been called hermit spiders from the habit staying in their retreats during the day; the name eunuch spiders has been used for "Nephilengys" alone. Males may sever parts of their palpal bulbs after copulation. Females are from 10 mm to 28 mm