Invertebrates are animals that lack a backbone. Invertebrates account for more than 97% of all species alive today. 

The first animals to have evolved were invertebrates.

Fossil evidence of invertebrates dates back to the late Precambrian, 600 million years ago. Invertebrates evolved from single-celled microorganisms.

Since invertebrates do not have bones, a bony skeleton, or a backbone, they must instead gain structural support for their bodies in different ways.

Inverterbrates include:

Marine Marine HabitatsAquariumsGlobal OceansOcean Weather
Vertebrate FishesMammalsReptilesAmphibiansCartilaginous FishesSharks
Invertebrate ArthropodMolluscaEchinodermsCnidaria
Conservation Status Critically EndangeredEndangeredNear ThreatenedVulnerableLeast ConcernData DeficientNot Evaluated