Are Extreme Anatomical Modifications Required for Fish to Move Effectively on Land? Comparative Anatomy of the Posterior Axial Skeleton in the Cyprinodontiformes.

Many teleost fishes with no apparent modifications for life on land are able to produce effective terrestrial locomotor behaviors, including a ballistic behavior called the "tail-flip" jump. Cyprinodontiformes (killifishes, Teleostei: Atherinomorpha) that live at the water's edge vary in morphology and inclination to emerge onto land. Do fish with an amphibious predisposition have extensive modification of the propulsive region of the body when compared to fully aquatic relatives? We quantified body shape and anatomy of the caudal peduncle and tail (the propulsive organ on land and in water) in 11 cyprinodontiform species and two outgroup taxa (Atherinomorpha).