Flatworms and roundworms are said to be invertebrates because?

A. they are small animals
B. they can live inside the vertebrates
C. some of them are unicellular
D. they have no backbones

Correct Answer:

Option D – they have no backbones

Explanation

– The most familiar invertebrates include the Protozoa, Porifera, Coelenterata, Platyhelminthes, Nematoda, Annelida, Echinodermata, Mollusca and Arthropoda.

– Invertebrates are animals that neither possess nor develop a vertebral column, derived from the notochord.