Genital parasite crabs are struggling to find sex partners


Dr Nicolas Chiaradia

Castrator pea crabs live up to their name. They live inside the sex organs of marine molluscs and prevent them from reproducing. But it turns out the pea crabs’ parasitic ways also make it terribly tricky for them to find a mate.

Castrator pea crabs (Calyptraeotheres garthi) are tiny parasitic crustaceans found off the east coast of South America, from southern Brazil down to Argentina’s Valdez Peninsula. They spend most of their adult lives in the sex organs of various slipper limpets.

“They castrate, which means that they halt or stop the reproduction of the snail they use as host,” says Emiliano Ocampo at the National Council of Scientific Research in Mar del Plata, Argentina.

Pea crabs only seem to parasitise female limpets. These molluscs normally store their eggs in their sex organs, but won’t lay eggs if they have a resident pea crab. It