what is the difference between lobe -finned fish and an amphibian?

Answer 1

It is not enough to say merely that lobe-finned fish have gills and amphibians have lungs, because lungfish, a lobe-finned fish, have both. A more crucial difference is the metamorphosis that amphibians undergo in which they lose their gills entirely. (The word "amphibian" comes from the Greek words "amphi-" and "bios", which together mean "life of both kinds".) Lungfish do not metamorphosize. They never lose their gills. Amphibians do metamorphosize, reaching a stage in which they only obtain oxygen through their lungs or directly through their skin.

There are a couple of exceptions, though. The axolotl and the mud puppy are two closely related salamanders who do not metamorphosize and retain their gills throughout their lives. Why are they not called fish, then? Because scientists believe that this phenomenon, called neoteny, evolved later. In other words, the axolotl's ancestor was likely an amphibian who DID lose its gills, but for some reason they have since evolved to stay in their larval form. Evidence for this includes the fact that axolotls can be induced into transforming to an adult form if given iodine injections or a certain hormone. (This often results in death, or at least a greatly shortened life span.) Another example of how evolution does not always proceed in the same "direction", and how taxonomic groups are based on lineage, not simply physical traits.

So metamorphosis is perhaps the principle difference. There are others, however. For instance, nearly all amphibians produce lims with digits, or fingers/toes, which lobe-finned fish lack. There are also certain features of the amphibian skull that lobe-finned fish do not share.

Answer 2

One is a fish, it has gills and lives in water. One is an amphibian, it lives in water and on land. Lobe-finned fishes are not amphibious.

Answer 3

"i in reality understand that fish lay eggs and mammals do no longer." As some mammals lay eggs even as some fish supply beginning to stay youthful, what you imagine you recognize could require some rethinking. Mammals are warmth-blooded critters; familiar as endotherms. They generate warmth interior their bodies. Fish do not. Mammals, a minimum of for the duration of area of their existence, have some hair or fur someplace or different, yea, even dolphins. Fish do not. Mammals feed their youthful milk from mammary glands on females (or plastic bottles each now and then). Fish do not. Mammals have a decrease jaw composed of a unmarried bone stated as the dentary, and it truly is joined to the cranium by technique of a link stated as the dentary-squamosal. Fish have multi-boned decrease jaws, and no dentary-squamosal joint. "I also do no longer understand the way a shark is a fish it does no longer lay eggs." it truly is in reality a fish in a loose that technique of the note. some sharks, as for some fish, supply beginning to stay youthful. different sharks, as with different fish (and a couple of mammals), lay eggs.