Is anatomical degeneration impossible in vertebrates?

[insectilluminatigetshrekt]

This is a really interesting point actually. It holds up within arthropods as well. Cristaceans, mites, and holometabolous insects have distinct larval stages and those are the clades with many hyper specialized parasites and degenerated forms. Non mite arachnids, myriapods and non holometabolous insects have young that largely resemble the adults and mostly lack such forms. Coocoid scale insects are exception among non holometabolans. Im sure theres other excrptions, but generally it seems that more morphological plasticity in an animals life cycle = more ability to do all sorts of weirdness.