Biology From Invertebrates to Vertebrates

From Invertebrates to Vertebrates

• Humans are vertebrates—animals with backbones—as are many of the animals we interact with and observe in our daily environment. Our curiosity about this group of animals is natural. The vertebrates include some of the largest and fastest animals on Earth.

• But the vast majority of animal species, and individual animal organisms, are invertebrates. All animals have an invertebrate ancestry.

• As we proceed in our survey of animals from invertebrates to vertebrates, we’ll examine two of the most widespread and successful groups of protostome invertebrates, the mollusks and the arthropods.

• We’ll then make our way toward the vertebrate branch of the tree of life with an exploration of the two most important phyla of deuterostomes, the echinoderms and the chordates.

• We’ll see how the vertebrate line arose from the chordates and progressed through fish to land animals, and we’ll find the twig on the tree where the human species is placed.