Invertebrate animals belong to the Animal Kingdom and are characterized by the absence of a vertebral column and skull. This group includes butterflies, ants, worms, earthworms, sea urchins, and sponges, among other animals.
Invertebrates represent approximately 94% of all animals and are divided into several phyla, including: Porifera, Cnidaria, Platyhelminthes, Nematoda, Mollusca, Annelida, Echinodermata, and Arthropoda.
