![]() Crabs frequently move between sponges, mostly at night. It is hypothesized that males occupy “home ranges” which females do not. ![]() Males, despite their greater mobility, find new hosts slower than females. Males and females differ in their rate of discovery of new hosts. carnosus sponges and disperse from this host to other species in the environment. The majority of crabs carried caps which matched their host sponge or ascidian, but mis-matches varied seasonally with a winter peak following the breeding season. hilgendorfi exhibits a preference for certain sponges. Use of sponge and ascidian species varies seasonally, with Halichondria sp. carnosus caps also decay less rapidly than caps made from other sponges. Caps are made from the sponge Suberites carnosus more often than from other available sponges. ![]() Cap life is independent of crab size, differs between different cap species and is influenced by the presence of other crabs who can dislodge caps through aggressive behaviour. Caps decrease in size with time, but conceal the crabs which commonly occupy exposed sites on sponges. It occurs during intermoult periods, with females making most of their caps at night. ![]() Cap area increases non-linearly with crab size, and caps are normally two to three times as large as the crabs. hilgendorfi uses 12 (of 16 available) species of sponge and 3 species of ascidians to construct caps, which are carried by the crabs using their last two pairs of legs. The aim was to investigate patterns of seasonal use, cap making behaviour, cap turnover, the effect of intraspecific interactions on cap life and the effect of movement of crabs between hosts on background matching. From May 1977 to February 1979, the use of sponges and ascidians by Cryptodromia hilgendorfi was studied in Moreton Bay, Queensland, Australia. ![]()
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