Reaches the adult stage is the correct answer. When an intervebrate reaches the adult stage it has most likely stopped growing and can finally begin reproduction, passing further down the line his genes and the genes of his ancestors.
Invertebrates are the animals that do not possess a vertebral column. The examples of invertebrates includes arthropods, annelids, cnidarians and mollusks. Invertebrates are the largest class of organisms. They consists of three common parts called as head, thorax and abdomen. The structure restricts any change in the size or length after reaching the adult stage.
