Basically, I mean an animal evolving to radically simplify its anatomical structure, or losing several major body systems. I will demonstrate some examples in arthropods, a phylum of animals with very complex anatomy and behaviors, in many ways analogous to vertebrates. ‘Degeneration’ as I will ca…

These all good examples of simpler forms of degeneration. Indeed limb loss is actually quite common among vertebrates, as is reduction of various skeletal elements. But it seems few if any of them have undergo extreme degeneration of most/all their organ systems. Male anglerfish are the only example…

Fascinating speculation, thanks for suggesting it. I think it becomes more conceivable if we avoid having tetrapods constantly jump to mind as canonical examples of vertebrates. For whatever reason, the tetrapod developmental program is quite constrained (although naked mole rats are truly, truly st…

[image] insectilluminatigetshrekt: Then there is the fact many insects lack functional (or any) mouthparts as adults, and have degraded digestive systems. Brook lampreys also have degenerate, nonfunctional digestive systems as adults.

In the advanced snakes, pretty much all of the paired organs are reduced to one…one lung, kidney, ovary/testes. Similarly, in Order Gymnophiona, caecilian amphibians have lost at least one lung. The commonality seems to be the tubular body plan is too long and narrow to warrant duplicates. Also co…

The best example I can think of is canine transmissible venereal tumor. It is a clump of dog cells that no longer behaves like a dog, instead acting as a parasite on other dogs. Apparently it has been around for thousands of years now.

Fish do seem to have the greatest capacity for this. Male anglerfish ofc, some fish changing sex, and some adult lampreys having non feeding adults as mentioned by someone else. I guess the real question is, why do fish have so much more developmental plasticity than tetrapods? And for that matter…

Not sure you can say that terrestrial insects have less capacity for developmental changes than crustacea. I mean … You have complete metamorphosis, with the larvae sometimes having much less morphological complexity than the adults. Some even have hypermetamorphosis, where they undergo radical chan…

True true, but no insect can quite compare to rhizocephalans and dendrogastrids, or cryptoniscid isopods. Female streps get close but even they still somewhat resemble an insect. And the point of hermaphroditism being extremely rare in insects but common in crustaceans still holds.

Disagree on a “larva” in metamorphosis having less complexity: the genes that function for being a tadpole get completely superceded for almost every organ system as the sexual adult slowly develops; the lungs aren’t built/restructured from the gills, for instance-- and where do the bony legs come f…

Is anatomical degeneration impossible in vertebrates?

Nature Talk

insectilluminatigetshrekt November 7, 2024, 2:23am 16

Oh wow, this is totally new to me! I had no idea snakes had this level of organ reduction.

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Is anatomical degeneration impossible in vertebrates?

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