Animated coloured scanning electron micrograph (SEM) of Hermit crab (Pagurixus sp.) in a marine gastropod shell. The genus Pagurixus is among the smallest known hermit crabs. In Moorea, it competes with a slightly smaller amphipod (Polynesoecetes kekeae) to occupy the same type of snail shell. A hermit crab requires an increasingly larger shell as it grows. When all shells are occupied, the hermit crab will fight another crab or simply remove a weaker rival. In this case, the hermit crab dismantles the sand grain shell entrance constructed by the amphipod, then eats the amphipod silk (or glue ) as sand is removed. The hermit crab then uses the larger of its two claws to probe the shell in an attempt to grasp some part of the amphipod (often the antenna) to pull it from the shell.