Biology, 9th ed, Sylvia Mader Chapter 31 Chapter 31 The Vertebrates The Vertebrates

Lancelet, Branchiostoma

Outline Chordates Non-vertebrate Chordates Vertebrates Fishes Amphibians Reptiles Birds Mammals

Chordates Phylum Chordata Four Main Characteristics Notochord Dorsal Tubular Nerve Cord Pharyngeal Pouches Postnatal Tail

Invertebrate Chordates Notochord persists and is never replaced by a vertebral column Lancets (Subphylum Cephalochordata) Sea Squirts (Subphylum Urochordata)

Sea squirt, Halocynthia

Vertebrates Subphylum Vertebrata Internal jointed skeleton of vertebrates is living tissue that grows with the animal Main axis of skeleton consists of vertebral columns and a skull that encloses the brain Cephalization is accompanied by sense organs Evolution of jaws and predation Amnion allows reproduction on land

Phylogenetic Tree of the Chordates Biology, 9th ed, Sylvia Mader Phylogenetic Tree of the Chordates Chapter 31 The Vertebrates 1.B.2: chordate development

Vertebrate Features Living endoskeleton with vertebral column Closed circulatory system Paired appendages Efficient respiration and excretion High degree of cephalization Adapted to active lifestyles

Biology, 9th ed, Sylvia Mader Ectotherms Chapter 31 The Vertebrates Ectotherms – depend on the environment to regulate body temperature. Fish Amphibians – able to live in environments where the temperature fluctuates greatly Most reptiles – allows them to survive on a fraction of the food per body weight required by birds and mammals; behaviorally adapted to maintain warm body temperature by basking in the sun 2.A.1: Ectothermy is the use of external thermal energy to help regulate and maintain body temperature.

Biology, 9th ed, Sylvia Mader Endotherms Chapter 31 The Vertebrates Endotherms – can use metabolic heat to maintain a constant internal temperature; endothermy may be associated with their efficient nervous, respiratory, and circulatory systems. Birds – unlike, other reptiles, generate internal heat Mammals 2.A.1: Endothermy is the use of thermal energy generated by metabolism to maintain homeostatic body temperatures.

Jawless fishes (agnathans) Fishes with jaws Cartilaginous (chondrichthyes) Bony (osteichthyes)

Amphibians Modern amphibians include three groups: salamanders and newts frogs and toads caecilians

Evolution of the amniotes The amniotes consist of three lineages: a. The turtles, in which the skull has no openings behind the orbit—eye socket (anapsid). b. All the other reptiles, in which the skull has two openings behind the orbit (diapsid). c. The mammals, in which the skull has one opening behind the orbit (synapsid)

Timeline of the evolution of the amniotes Biology, 9th ed, Sylvia Mader Timeline of the evolution of the amniotes Chapter 31 The Vertebrates 4.B.4: Meteor Impact on Dinosaurs Dinosaurs dominated Earth for about 170 million years before they died out at the end of the Cretaceous period, 65 mya. One hypothesis for this mass extinction – a massive meteorite struck the Earth near the Yucatan Peninsula; this disrupted existing ecosystems and destroyed many living things. The hypothesis is supported by a layer of the mineral iridium, which is rare on Earth but common in meteorites.

Reptiles Most reptiles today live in the tropics or subtropics lizards and snakes live on soil turtles, crocodiles, and alligators live in water

Birds Bird classification is based on beak and foot types, and some on habitats and behaviors. Birds of prey have notched beaks and sharp talons. Shorebirds have long slender bills and long legs. Waterfowl have webbed toes and broad bills

Mammals Monotremes are mammals that have a cloaca and lay hard-shelled amniote eggs (duckbill platypus and two species of spiny anteaters). Marsupials begin development inside the mother’s body but are then born in a very immature state. Placental Mammals are dependent on a placenta, an organ of exchange between maternal and fetal blood.

Major Orders of Mammals Perissodactyla Horses Artiodactyla Deer Carnivora Cats Primates Monkeys Cetacea Whales Chiroptera Bats Rodentia Mice Proboscidea Elephants Lagomorpha Rabbits

Biology, 9th ed, Sylvia Mader Chapter 31 Ending Slide Chapter 31 The Vertebrates The Vertebrates