Abstract
The vent crab Xenograpsus testudinatus was firstly discovered in 2000 at the hydrothermal vent field off the coast of Kueishan Island. The present study attempts to understand the adaptive reproduction of this crab living in an extreme environment by examining its spatial and temporal distribution and isotopic signatures. The seasonal variation of the female-male ratio suggests that ovigerous females may migrate from beneath the vent orifice to the vent-periphery region to release their larvae to avoid the larvae contacting high toxic plumes, and then returns to the vent orifice habitat. We used variation of the isotopic crab signatures as indicators for this unique female migration. Our results showed that this vent crab evolved an adaptive modulation of reproductive behavior to successfully survive and propagate in an oceanic shallow hydrothermal vent field.