Do Fish Have Ribs?
Yes, most fish have ribs. However, their rib structure differs significantly from that of land vertebrates.
Unlike the rib cage of mammals, which forms a complete protective structure around the lungs and heart, fish ribs are simpler. Most bony fish (excluding cartilaginous fish like sharks and rays) possess two sets of ribs:
- Dorsal ribs: These attach to the upper part of the vertebral arches.
- Ventral ribs: These attach to the lower part of the vertebral arches.
Importantly, these ribs do not join in the front to form a closed cage. The upper (dorsal) ribs are considered to be evolutionarily related to the ribs found in land vertebrates. The development of a rib cage with a sternum (breastbone) first appeared in reptiles.
Several sources confirm this:
- Britannica states: "Fish have two sets of ribs, which attach to the upper and lower parts of the vertebral arches and which do not join in front."
- A Reddit AskScience post notes: "Fish (excluding elasmobranchs which are the cartilaginous fish like sharks and rays) have spines, ribs, fin bones, jaws, other special bones."
- A biology resource explicitly mentions: "Many fishes have 2 sets of ribs: dorsal and ventral ribs."
The space where a rib cage might be in other animals is instead occupied by other organs and tissues within the fish's body.
