Hi Lisa- I’m sorry- I think I sent my reply to only you in answering your question. I will attach a photo of three hyplural verts that are a little more complete than the one from the Cooper River. Note the last vertebrae attachment, followed by the hard tail structure. The structure stiffens the rigid caudal fin of fish like tuna, bluefish, and marlin that swim with tuniform motion, rapid vibration of the tail for speed, as compared with fish, such as bass and bream, that use undulating motion, a soft full caudal fin, and therefore less speed (but allows for hovering in easy currents).