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Since 1979 it is known that, in Australian species of Uca, female waving exists in addition to usual male display. The present paper deals mainly with female waving in U. polita studied in Darwin (North Australia). A few remarks on U. dampieri, U. vomeris, U. seismella and U. hirsutimanus are added. The species mentioned are members of two species groups or subgenera, which characterizes female waving as an ancestral (plesiomorph) trait. Frame by frame analysis of film sequences (open air shots) indicate homology of movements in the two sexes of U. polita. As in males, waving of females can be combined with locomotion on radial paths starting from the burrow entrance and the display is performed in series with a corresponding number of gestures. Unlike males, waving females mostly use both their chelipeds and tend to show shorter durations with regard to many of the waving parameters chosen. However, significant differences refer only to a limited number of parameters. The biological context of female waving was gathered from films and field observations. High intensity waving is released by conspecifics approaching from far (wanderers without burrows) and from the neighbourhood. Typically, only females and small males elicit high intensity display in a resident female. Waving normally stops in presence of larger males, especially of the male living in a resident breeding unit with the female in question. In spite of this, a pure agonistic (defensive) character of female waving is unlikely. Advertising of breeding condition seems to play a role similar to that in males. The few displaying females that exist in a given colony (about 2.5% in U. polita) show signs of special sexual excitement: brightening of carapace colours and sometimes spontaneous performance of waving, i.e. display immediately after emergence from the burrow in absence of any conspecific.

SUMMARY Classification and evolution of sound production in ocypodid and grapsid crabs (Crustacea, Brachyura) The sounds of semiterrestrial ocypodid and grapsid crabs ‐ mostly epiphenomenal characters of vibrations signals ‐ were studied outdoors as well as in a special indoor terrarium allowing observation of underground behaviour. Sounds are classified in four groups according to the method of sound production. They are produced by respiration, stridulation, percussion, and convulsion, respectively. “Convulsion” is a descriptive name of free vibrations (shivering or shaking movements) the amplitude of which is very small. In Uca they can be heard as humming or honking noises. Contrary to previous assumptions, they are strictly synchronous with movements of the cheli‐peds. Being subdivided in syllables these sounds can be understood as derivatives from unaccented percussive sounds (“drum whirls”). An exaggerated form of percussion of these honking species of Uca probably became integrated into the waving display (in this group always known as “jerking wave”). The non‐directional character of evolution as visible in the sound production of the Uca species mentioned above can also be read from the relations between percussion and stridu‐lation in semiterrestrial crabs. Apparently, there was an evolution from stridulation to rapping movements within the grapsid genus Sesarma. In the ocypodids Ocypode and Uca, however, stridulation evolved from percussion.