Affinities of dipnoi?

Dipnoi, also known as lungfish, are a group of freshwater fish that have both fish-like and amphibian-like characteristics. They are considered to be a transitional group between fish and tetrapods (four-limbed vertebrates). Some of the affinities of dipnoi include:

1. Lung-like organs: Dipnoi have a unique respiratory system that includes lung-like organs, which allow them to breathe air in addition to extracting oxygen from water through their gills. This adaptation is similar to that of amphibians, which also have lungs for breathing air.

2. Fleshy fins: Dipnoi have fleshy, lobed fins that are more similar to the limbs of tetrapods than the fins of other fish species. This suggests a closer evolutionary relationship between dipnoi and tetrapods.

3. Ability to aestivate: Some species of dipnoi are capable of aestivation, a state of dormancy similar to hibernation that allows them to survive in dry conditions by burrowing into mud and breathing air through their lungs.

4. Primitive characteristics: Dipnoi retain some primitive characteristics that are more similar to early vertebrates, such as a single lung and a spiral valve intestine.

Overall, the affinities of dipnoi suggest that they are an important group in understanding the evolutionary transition from fish to tetrapods.