The red clawed crab, Chiromantes haematocheir (formerly Sesarma haematocheir) releases its larva into tidal rivers to coincide with nighttime high tides, presumably to maximise transport of larvae in the water from the release site and/or to minimise predation of the larvae. This picture from Saigusa (1982) illustrates a female crab releasing her larvae. This behaviour is coordinated by a circatidal clock.