Die Wollkrabbe hält mit Hilfe der beiden letzten, zu Haltebeinen umgewandelten Laufbeinpaare Schwämme oder Ascidienkolonien über ihren Rücken. Eine ungetarnte Krabbe bearbeitet einen Schwamm und setzt ihn sich auf den Rücken. Versuche mit Pappe zeigen, daß die Tiere individuell verschiedene Techniken des Ausschneidens entwickeln können.

Dromia vulgaris (Dromiidae) holds cases of sponges or Ascidia colonies pressed onto its back by means of the specialized last two pairs of ambulatory appendages. The cover appears to offer the animal protection from the octopus, its main predator. An uncamouflaged Dromia which found a suitable sponge (presumably optically) climbs it and begins to detach pieces of it around the circumference within reach of its chelipeds, thus dismounting the top part of the sponge from its base. The loosened sponge is then worked on the underside until it fits the curvature of the carapax. The main method of putting on the cover is lying on the back with all legs holding the case and turning it to the right position, then somersaulting back into the upright position and simultaneously sliding the cover over the abdomen onto the back.