Visually mediated species recognition in the fiddler crab Uca mjoebergi

Mating signals are often directed at numerous senses, and provide information about species identity, gender, receptiveness, individual identity and mate quality. Male fiddler crabs of the species Uca mjoebergi typically have an enlarged yellow claw which they use for fighting and attracting a mate using a waving action.

Experiments were conducted between Sept 03' to Jan '04 in the vicinity of the mangrove boardwalk in the East Point Reserve, Darwin, NT.

The experiment was designed to demonstrate the use of claw colouration as a species recognition signal in the fiddler crab Uca mjoebergi. To test this, females were given a choice between size-matched, and handed matched U.signata and U.mjoebergi males. The colour of the males claw was manipulated using Dulux Tinytin gloss enamel paint.

Claw colour was found to be the dominant morphological feature in identifying conspecific males in U.mjoebergi.

Measurements taken during every trial included: carapace size (males and females), treatment (males), claw size (males), claw side (males), number of trials, trial arrangement, and female choice.