
Pea Crab Males Risk Life to Mate Inside Mussel Shells
The pea crab, a tiny parasite living inside mussels, exhibits distinct sexual dimorphism where females remain permanently inside the host while males exit to mate. Males possess specialized swimming adaptations and hardened exoskeletons to navigate the open water, despite facing significant risks of injury or death during these excursions. This behavior is driven by the high reproductive payoff, as a single female can produce over 9,000 eggs, with larval stages eventually returning to settle in new mussel hosts.

