Many insects and all terrestrial crabs (as well as other clades) have an aquatic life cycle stage: their eggs need to be laid in and to hatch in water; after hatching, there is an early aquatic form, either a nymph or larva.
Many insects have an aquatic life cycle stage. All terrestrial crabs (as well as other clades) have an aquatic life cycle stage. Their eggs need to be laid in and to hatch in water. There is an early aquatic form, either a nymph or larva. This is after hatching.