How do jellyfish defy evolution?

Answer 1

I actually believe that jellyfish confirm instead of defy evolution.

While many details of the phylogeny of Cnidarians (sea anemones, corals, hydras and jellyfish) have yet to reach scientific consensus, the overall structure of the evolutionary tree has recently started to come into focus with the help of molecular analysis. The large and diverse phylum Cnidaria diverged from the Bilateria phylum about 600 million years ago. It is currently undecided whether the diploblastic (two-layered) condition of cnidarians results from a secondary simplification of a triploblastic ancestor of bilaterians, or from a diploblastic common ancestor, since cnidarians possess most of the genes that are implicated in mesoderm (middle layer) development in bilaterians. The expression of these genes in modern cnidarians does not confirm the simplification hypothesis, however, since bilaterians may well have co-opted their function after divergence. Future molecular studies will likely resolve this issue.

Early in its evolutionary history, the Cnidaria phylum split into two major lineages: the class Anthozoa (anemones and corals), and the superclass Medusozoa. Medusozoans encompass three classes, Hydrozoa (hydras and hydromedusae), Scyphozoa (true jellyfishes), and Cubozoa (box jellies). Most medusozoans generally alternate between an asexual polyp phase and a sexually reproducing medusa (jellyfish) phase. Certain lineages subsequently lost their medusa phase, such as freshwater hydras.

I would link to the relevant scientific papers supporting my view, but links are not permitted here. However, it is certainly clear that evolution is not defied by cnidarian phylogeny.

Answer 2

I actually believe that jellyfish confirm instead of defyevolution.While many details of the phylogeny of Cnidarians (sea anemones,corals, hydras and jellyfish) have yet to reach scientificconsensus, the overall structure of the evolutionary tree hasrecently started to come into focus with the help of molecularanalysis. The large and diverse phylum Cnidaria diverged from theBilateria phylum about 600 million years ago. It is currentlyundecided whether the diploblastic (two-layered) condition ofcnidarians results from a secondary simplification of atriploblastic ancestor of bilaterians, or from a diploblasticcommon ancestor, since cnidarians possess most of the genes thatare implicated in mesoderm (middle layer) development inbilaterians. The expression of these genes in modern cnidariansdoes not confirm the simplification hypothesis, however, sincebilaterians may well have co-opted their function after divergence.Future molecular studies will likely resolve this issue.Early in its evolutionary history, the Cnidaria phylum split intotwo major lineages: the class Anthozoa (anemones and corals), andthe superclass Medusozoa. Medusozoans encompass three classes,Hydrozoa (hydras and hydromedusae), Scyphozoa (true jellyfishes),and Cubozoa (box jellies). Most medusozoans generally alternatebetween an asexual polyp phase and a sexually reproducing medusa(jellyfish) phase. Certain lineages subsequently lost their medusaphase, such as freshwater hydras.I would link to the relevant scientific papers supporting my view,but links are not permitted here. However, it is certainly clearthat evolution is not defied by cnidarian phylogeny.

Answer 3

I actually believe that jellyfish confirm instead of defyevolution.While many details of the phylogeny of Cnidarians (sea anemones,corals, hydras and jellyfish) have yet to reach scientificconsensus, the overall structure of the evolutionary tree hasrecently started to come into focus with the help of molecularanalysis. The large and diverse phylum Cnidaria diverged from theBilateria phylum about 600 million years ago. It is currentlyundecided whether the diploblastic (two-layered) condition ofcnidarians results from a secondary simplification of atriploblastic ancestor of bilaterians, or from a diploblasticcommon ancestor, since cnidarians possess most of the genes thatare implicated in mesoderm (middle layer) development inbilaterians. The expression of these genes in modern cnidariansdoes not confirm the simplification hypothesis, however, sincebilaterians may well have co-opted their function after divergence.Future molecular studies will likely resolve this issue.Early in its evolutionary history, the Cnidaria phylum split intotwo major lineages: the class Anthozoa (anemones and corals), andthe superclass Medusozoa. Medusozoans encompass three classes,Hydrozoa (hydras and hydromedusae), Scyphozoa (true jellyfishes),and Cubozoa (box jellies). Most medusozoans generally alternatebetween an asexual polyp phase and a sexually reproducing medusa(jellyfish) phase. Certain lineages subsequently lost their medusaphase, such as freshwater hydras.I would link to the relevant scientific papers supporting my view,but links are not permitted here. However, it is certainly clearthat evolution is not defied by cnidarian phylogeny.