why the invertebrates is not considered a formal taxonomic group of animals, unlike the vertebrates. ?

7 Answers

Relevance
  • cosmo
    Lv 7
    2 months ago

    There are lots of ways to not have a spinal cord.

  • 2 months ago

    Big surprise for you is they are. The largest of phylums with many subphylums..

  • 2 months ago

    Because there is such a huge variety of invertebrates that they have to break them up into smaller categories.

  • Anonymous
    2 months ago

    Because Vertebrates share a common ancestor within the group known as chordates. Some chordates are not vertebrates so they are invertebrates. To have a taxon that includes all invertebrates, it will include all animals other than vertebrates and it will include some chordates. That means some chordates will be classified in the same taxon as worms, insects, sponges, jellyfish and mollusks even though they are actually more closely related to vertebrates. That sort of classification is not very useful or informative of evolutionary relationships. 

    Currently the Kingdom Animalia is divided into many Phyla. One of them is Phylum Chordata, and it includes some invertebrates and all vertebrates. There is no Phylum Vertebrata or Phylum Invertebrata. The informal group invertebrates includes all animal phyla plus some species within the Phylum Chordata. Since there is no formal taxon known as Invertebrata, the invertebrates are therefore an informal group. 

  • What do you think of the answers? You can sign in to give your opinion on the answer.
  • ?
    Lv 7
    2 months ago

    Because the only thing they have in common is that they don't have something (backbone) . Jelly fish and ant don't have a backbone, not really a commonality .

  • 2 months ago

    Vertebrata is just a single subphylum of the phylum Chordata. Invertebrates are spread over so many phyla that calling something an invertebrate gives you little more information than saying it is an animal. The purpose of classification is to convey as much information as compactly as possible.

  • ?
    Lv 7
    2 months ago

    Because vertebrates have invertebrate ancestors.  A clade comprising the invertebrates would also have to include the vertebrates.

    ...and we already have that.  That's "Kingdom Animalia."

Still have questions? Get answers by asking now.