Sponge masking and related preferences in the spider crab Thacanophrys filholi (Brachyura : Majidae)

Abstract

Spider crabs, Thacanophrys filholi, collected from Kaikoura, New Zealand, were predominantly masked with four species of sponge: Lissodendoryx sp., Iophon laevistylis, Paresperella sp. and Dysidea sp. Other species of sponge, as well as ascidians, brachiopods, anomiid bivalves and tube-dwelling polychaetes, were also part of the extensive epifauna covering the crabs. The act of masking is described, and the location of the hooked setae that allow attachment of material to the crabs exoskeleton is mapped. When crabs in the laboratory were simultaneously offered equal volumes of the four main sponge species with which they masked in the field, they masked equally with Lissodendoryx sp. and Dysidea sp. in preference to I. laevistylis and Paresperella sp. These masking preferences were influenced by the relative volumes in which each species of sponge was presented to the crabs.