Freshwater crab
A crab that lives primarily in freshwater, belonging to one of several lineages that independently adapted to rivers, streams, or lakes.
Crab: A decapod crustacean with a broad body, a reduced abdomen folded beneath the thorax, and usually five pairs of legs. Freshwater crabs share the crab body plan but belong to multiple lineages.
Direct development: A life history in which young hatch in a form resembling small adults, without a free-swimming larval stage. Many freshwater crab lineages reduce dependence on open water by producing developed hatchlings.
Aquatic food web: A network of feeding relationships among organisms in an aquatic ecosystem. Crabs consume detritus and smaller organisms, while fish and other predators may eat them.
Marine crab: A crab that lives primarily in saltwater environments such as coastal seas and the open ocean. Marine crabs show the ancestral habitat conditions from which freshwater lineages diverged.
Decapoda: An order of crustaceans that includes crabs, lobsters, crayfish, and shrimps, typically with five pairs of thoracic legs. Freshwater crabs are decapods, a group whose members occupy both aquatic and terrestrial habitats.
Crab larva: An early developmental stage of a crab, commonly including planktonic zoea and megalopa forms. Marine-derived larval stages help explain why many crabs cannot reproduce far from the sea.
Bioindicator: An organism whose presence, absence, or condition provides evidence about environmental quality. Local crab populations can respond to pollution and habitat disturbance, though they are not universal indicators.
Land crab: A crab adapted to spend most of its adult life on land, usually returning to water to reproduce. Land crabs emphasize terrestrial adaptation, while freshwater crabs remain associated with inland waters.
Crustacean: An arthropod with a hard exoskeleton, jointed limbs, and two pairs of antennae, including crabs, lobsters, and shrimps. Their crustacean ancestry supplies the shared body plan and molting cycle.
Amphidromy: A life cycle in which larvae drift downstream to develop in the sea and juveniles later migrate upstream. Some freshwater crabs retain a sea-dependent larval phase despite adult freshwater habitats.