Fish anatomy is the study of the form or morphology of fish. It can be contrasted with fish physiology, which is the study of how the component parts of fish function together in the living fish. In practice, fish anatomy and fish physiology complement each other, the former dealing with the structure of a fish, its organs or component parts and how they are put together, such as might be observed on the dissecting table or under the microscope, and the latter dealing with how those components function together in living fish.
Anatomical directions and axes
Skeleton of a bony fish
Skeletal structure of a bass showing the vertebral column running from the head to the tail
Skeletal structure of an Atlantic cod
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the spine and are supported only by muscles.
Dorsal fin of a chub (Squalius cephalus)
Skeleton of a lingcod, a ray-finned fish
Lobe-finned fishes, like this coelacanth, have fins that are borne on a fleshy, lobe-like, scaly stalk extending from the body. Due to the high number of fins it possesses, the coelacanth has high maneuverability and can orient its body in almost any direction in the water.
Pectoral fin with fleshy lobe of Latimeria chalumnae (Citron / CC-BY-SA-3.0)
