ABSTRACT
This chapter employs the zebrafish Danio rerio as a case study to illustrate the development of the muscles of all the five types of fins (pectoral, pelvic, caudal, anal, and dorsal). The caudal fin is the first fin to develop in the zebrafish. It appears as a continuation of the zebrafish postcranial axial skeleton and is surrounded by the caudal fin fold with the mesenchyme condensation ventrally, where the first caudal muscles and bones will later develop. The chapter describes the dorsal and anal fin muscle development together, because of the striking similarity of both their adult anatomy and ontogenetic development. From very early development, the caudal fin is supported by musculature, while other fins appear as relatively simple homogeneous structures—fin folds or fin buds—that grow and acquire muscles much later in development.
