Crabs are neither amphibians nor reptiles; they are classified as crustaceans, which are a group within the class Malacostraca. Crustaceans are characterized by their hard exoskeleton, segmented bodies, and jointed limbs.
Unlike amphibians, which typically have a life cycle that includes a transition from a water-dwelling larval form to an adult form that can live on land, crabs are primarily aquatic and do not undergo such a transformation. While amphibians like frogs need to return to water to reproduce, most crab species thrive in marine or freshwater environments throughout their life.
Additionally, reptiles are a distinct class of animals characterized by scaly skin, laying hard-shelled eggs, and being cold-blooded. While some reptiles, like sea turtles, may share aquatic habitats with crabs, they belong to entirely different biological classifications. Crabs breathe through gills, much like fish do, which further separates them from reptiles.
In summary, crabs are crustaceans and not classified as amphibians or reptiles, highlighting the diversity of life forms and their unique adaptations to their environments.