Lungfishes

What are lungfishes? Lungfishes (Figure 1) are a group of fishes that, as their name suggests, possess a lung with which they breathe air, in addition to gills as in most other fishes. Along with the coelacanth, they belong to the Sarcopterygii, otherwise known as ‘lobe-finned’ fishes, named so due to the fleshy nature of their paired fins. These fins contain a similar arrangement of endoskeletal bones as we tetrapods do in our own arms (humerus, radius, ulna, etc.). They hold particular fascination for evolutionary biologists as the sister group — the most closely related living lineage — to the tetrapods (four-limbed vertebrates and all of their descendants). Once, they were even considered to be the direct ancestors of all tetrapods.