Trivia: Animal phyla are defined by vertebrae — which refers to what body part?
Brain
Spine
Heart
Eyes
The correct answer is Spine
So why is this answer correct? : The taxonomic system divides the animal kingdom into vertebrates and invertebrates. Vertebrae, or spinal columns, are found in humans and animals in the phylum Chordata. Although all mammals — and many non-mammals — have spines, more than 90% of the world’s animal species are invertebrates, with insects making up the lion’s share.