Lower and Higher Invertebrates with their differences

The invertebrates are usually classified as Lower Invertebrates and Higher Invertebrates.

Lower Invertebrates

  • The lower invertebrates are simple in body organization.
  • They are generally small in size.
  • These are thought to have originated in the main lines of evolution, near the base of the phylogenetic tree of Animal kingdom.
  • Lower Invertebrates includes Protozoa, Porifera, Coelenterata (Cnidaria), Platyhelminthes and Nematoda.

Higher Invertebrates

  • They possess a complex body organization.
  • They are generally larger in size.
  • These occupy a higher position in the phylogenetic tree of Animal kingdom.
  • Higher Invertebrates include Mollusca, Annelida, Arthropoda, and Echinodermata.

Lower and Higher Invertebrates

On the basis of some important features, there are some differences between lower and higher invertebrates as shown below:

Table 1: Differences between Lower Invertebrates and Higher Invertebrates



Lower Invertebrates

Higher Invertebrates

1. Size Smaller in size Larger in size
2. Body organization Body organization simple Body organization complex
3. Symmetry Radial, biradial or no symmetry Bilateral symmetry
4. Germ Layers Germ layers wanting or 2 or 3 germ layers Three germ layers present
5. Coelom No Coelom or a pseudo-coelom True Coelom
6. Mouth and Anus Generally, no separate mouth and anus Mouth and Anus are separate
7. Muscular Gut Absent Present
8. Blood Vascular System Not well developed Well developed


  1. Kotpal RL. 2017. Modern Text Book of Zoology- Invertebrates. 11th Edition. Rastogi Publications.
  2. Jordan EL and Verma PS. 2018. Invertebrate Zoology. 14th Edition. S Chand Publishing.

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