Ch 34 Vertebrates
Chapter 34 Vertebrates
Overview: Half a Billion Years of Backbones * Vertebrates are named for vertebrae, the series of bones that make up the vertebral column or backbone. * There are about 52,000 species of vertebrates, far fewer than the 1 million insect species on Earth. * Plant-eating dinosaurs, at 40,000 kg, were the heaviest animals to walk on land. * The biggest animal that ever existed is the blue whale, at 100,000 kg. * Humans and our closest relatives are vertebrates. * This group includes other mammals, birds, lizards, snakes, turtles, amphibians, and the various classes of fishes.
Concept 34.1 Chordates have a notochord and a dorsal, hollow nerve cord * The vertebrates belong to one of the two major phyla in the Deuterostomia, the chordates. * Chordates are bilaterian animals, belonging to the Deuterostomia. * The phylum Chordata includes three subphyla, the vertebrates and two phyla of invertebrates—the urochordates and the cephalochordates.
Four derived characters define the phylum Chordata. * Although chordates vary widely in appearance, all share the presence of four anatomical structures at some point in their lifetime. * These chordate characteristics are a notochord; a dorsal, hollow nerve cord; pharyngeal slits; and a muscular, post-anal tail. 1. The notochord, present in all chordate embryos, is a longitudinal, flexible rod located between the digestive tube and the nerve cord. * It is composed of large, fluid-filled cells encased in fairly stiff, fibrous tissue. * It provides skeletal support throughout most of the length of the animal. * While the notochord persists in the adult stage of some invertebrate chordates and primitive vertebrates, it remains only as a remnant in vertebrates with a more complex, jointed skeleton. * For example, it is the gelatinous material of the disks between vertebrae in humans. 2. The dorsal,
Overview: Half a Billion Years of Backbones * Vertebrates are named for vertebrae, the series of bones that make up the vertebral column or backbone. * There are about 52,000 species of vertebrates, far fewer than the 1 million insect species on Earth. * Plant-eating dinosaurs, at 40,000 kg, were the heaviest animals to walk on land. * The biggest animal that ever existed is the blue whale, at 100,000 kg. * Humans and our closest relatives are vertebrates. * This group includes other mammals, birds, lizards, snakes, turtles, amphibians, and the various classes of fishes.
Concept 34.1 Chordates have a notochord and a dorsal, hollow nerve cord * The vertebrates belong to one of the two major phyla in the Deuterostomia, the chordates. * Chordates are bilaterian animals, belonging to the Deuterostomia. * The phylum Chordata includes three subphyla, the vertebrates and two phyla of invertebrates—the urochordates and the cephalochordates.
Four derived characters define the phylum Chordata. * Although chordates vary widely in appearance, all share the presence of four anatomical structures at some point in their lifetime. * These chordate characteristics are a notochord; a dorsal, hollow nerve cord; pharyngeal slits; and a muscular, post-anal tail. 1. The notochord, present in all chordate embryos, is a longitudinal, flexible rod located between the digestive tube and the nerve cord. * It is composed of large, fluid-filled cells encased in fairly stiff, fibrous tissue. * It provides skeletal support throughout most of the length of the animal. * While the notochord persists in the adult stage of some invertebrate chordates and primitive vertebrates, it remains only as a remnant in vertebrates with a more complex, jointed skeleton. * For example, it is the gelatinous material of the disks between vertebrae in humans. 2. The dorsal,