Animals lacking .
As most animals lack backbones, most are invertebrates. Contrast with vertebrate animals. Indeed, subphylum Vertebrata, is the only taxon that does not consist of invertebrate animals.
Since evolved from invertebrate ancestors, essentially the invertebrates can be viewed as a paraphyletic taxon, that is, one that is equivalent to kingdom Animalia, the metazoans, but which lacks the vertebrate lineage.