Fig. 1.

A cartoon representation of key derived traits in pipefishes and their relatives. Syngnathid fishes such as the Gulf pipefish have increased numbers of vertebrae and an elongated head, are missing pelvic fins and ribs, and have an evolutionarily novel structure, the male brood pouch. Shown for comparison is the axial skeleton of a percomorph with more typical morphology, a threespine stickleback. Note that not all derived syngnathid skeletal features are depicted in this cartoon. For detailed, anatomical illustrations of syngnathid skeleton attributes, please see other studies [144, 145]