33-3 Form and Function in Chordates Chordates Vertebrate organ systems exhibit a wide range of complexity. This is seen in the different ways that vertebrates feed, breathe, respond, move, and reproduce. 1 of 64 2 of 64 Vertebrate Digestive Systems The digestive systems of vertebrates have organs that are well adapted for different feeding habits. Shark Salamander Lizard Carnivores have short digestive tracts with fastacting, meat-digesting enzymes. Herbivores have long intestines. Some have bacteria that help digest the tough cellulose fibers in plant tissues. 3 of 64 4 of 64 Vertebrate Digestive Systems Pigeon Cow Aquatic chordates such as tunicates, fishes, and amphibian larvae use gills for respiration. Land vertebrates, including adult amphibians, reptiles, birds, and mammals, use lungs. 5 of 64 6 of 64 1
Gills Water flows in through the fish s mouth. Muscles pump the water across the gills Each gill contains thousands of filaments that absorb oxygen from the water. Mouth Gill filament 7 of 64 8 of 64 Operculum: Water and carbon dioxide are pumped out through the operculum. Lungs Although the structure of the lungs varies, the basic process of breathing is the same among land vertebrates. Operculum 9 of 64 10 of 64 Vertebrate Vertebrate Salamander Lizard Primate Bird 11 of 64 12 of 64 2
Circulatory systems maintain homeostasis by transporting materials throughout animals bodies. Single- and Double-Loop Chordates that use gills for respiration have a single-loop circulatory system. Vertebrates with lungs have a double-loop circulatory system. 13 of 64 14 of 64 Single-loop circulatory system Double-loop circulatory system Heart Chambers During the course of chordate evolution, the heart developed chambers and partitions that help separate oxygen-rich and oxygen-poor blood traveling in the circulatory system. Fishes Most reptiles Crocodilians, birds, and mammals 15 of 64 16 of 64 In vertebrates with gills, such as fishes, the heart consists of two chambers: 1 Ventricle Most amphibians have three-chambered hearts. 2 Atria Most reptiles have a threechambered heart. 1 Atrium 1 Ventricle with partial division 17 of 64 18 of 64 3
Birds, mammals, and crocodilians have fourchambered hearts sometimes called a double pump. 2 Atria Excretory systems eliminate nitrogenous wastes. Gills, gill slits, and kidneys play an important role in excretion. 2 Ventricles completely divided 19 of 64 20 of 64 In addition to eliminating nitrogenous wastes, kidneys help maintain homeostasis by regulating the amounts of water, salt, and other substances dissolved in body fluids. Nonvertebrate chordates have a relatively simple nervous system with a mass of nerve cells that form a brain. Vertebrates have a more complex brain with distinct regions, each with a different function. 21 of 64 22 of 64 The vertebrate brain is divided into several parts: cerebrum, or thinking and learning region cerebellum, which coordinates movement and balance medulla oblongata, which controls many internal organs optic lobes, which are involved in vision olfactory bulbs, which are involved in smell 23 of 64 24 of 64 4
The size and complexity of the cerebrum and cerebellum increase from fishes to mammals. The skeletal and muscular systems support a vertebrate's body and make it possible to control movement. Bony Fish Amphibian Reptile Bird Mammal 25 of 64 26 of 64 Most vertebrates have an internal skeleton of bone or cartilage. The skeleton includes a backbone of individual bones called vertebrae. Ligaments connect vertebrae and allow the backbone to bend. Most vertebrates have fin or limb girdles that support fins or limbs. Almost all chordates reproduce sexually. 27 of 64 28 of 64 After fertilization, the development of chordates can be: Oviparous eggs develop outside the mother s body. Ovoviviparous eggs develop within the mother s body, but are born alive. Viviparous developing embryos obtain nutrients directly from the mother s body and are born alive. 29 of 64 Some vertebrates, such as most amphibians, produce many offspring but give them little care. This reproductive strategy favors populations that disperse and grow rapidly. Mammals and birds produce few young but care for them. This reproductive strategy aids survival in crowded, competitive environments. 30 of 64 5