In mid-Atlantic estuaries, three adult fiddler crabs (Uca pugilator, Uca pugnax, and Uca minax) undergo identical larval histories, with their adults occupying different ecosystem types varying by salinity and sediment size. Larvae of many benthic invertebrates metamorphose in response to ecological parameters such as habitat and adult chemical cues. We utilized field-caught larvae to test whether an adult crab's conspecific cues influenced the megalopa stage's duration and triggered settlement and subsequent metamorphosis. The three species of fiddler crabs had varying responses to the adult chemical cues and demonstrated their respective selectivities for choosing a settlement site. U.pugilator molted in all conditions regardless of salinity or adult exudate. U. pugnax molted the most in their conspecific water treatment, yet molted more often in 20ppt than 10 ppt. U. minax was the most selective and hardly molted at all, indicating other chemical stimuli may be necessary for stimulating and accelerating their molting and settlement site selection.