Difference between invertebrates and vertebrates

  • Invertebrates have no backbone

Monophyletic group-1 common ancestor

  • Invertebrates are not a monophyletic group
  • They come from many different groups

Inverts make up at least 95% of all extant (living) animal species

Over 1,000,000 described species on the planet

Estimated 10 – 30 million species have not yet been described- most are thought to be found in tropical rain forests – this number will probably decline as we continue to cut rain forests down

There are 3 domains of Life

  • Bacteria-prokaryotes
  • Archaea- prokaryotes
  • Eukarya-eukaryotes

Prokaryotic- cells lack nucleus

Eukaryotic- cells have membrane bound organelles, including a nucleus

Phylogenetic Tree of Life

Image result for phylogenetic tree


-In 2005 scientists created a new classification called “Supergroups”

-This system divided the eukaryotes into 6 monophyletic “supergroups”

-A range of protists (Protozoa – “animal like”)

-Unicellular, eukaryotic – they are not animals, plants or fungi (include many “groups” or “phyla”)


Porifera- sponges

Cnidaria-jellyfish, anenomes, coral

Ctenophora-comb jellies


Mollusca- Chitons, clams, snails, squids, octopus, slugs

Annelida- Segmented Worms

Arthropoda- Horshoe Crabs

Nematoda- Roundworms

  • Caenorhabditis elegans-good
  • Ascaris lumbricoides- bad

Rotifra- wheel bearers

Echinodermata- starfish

Chordata- Only phylum including vertebrate animals but it also includes some invertebrates