Chapter 29, 33.3: Vertebrate Animals and Homeostasis Key Concepts
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Chapter 29, 33.3: Vertebrate Animals and Homeostasis Key Concepts Major Diversity of Characteristics Homeostasis Vertebrates of Chordates © 2017 Pearson Education, Inc. Chordates: Bilaterian animal clade Deuterostomia Chordates comprise all vertebrates (~60,000 species) and two groups of invertebrates, the urochordates and cephalochordates All chordates share 5 characteristics… Endostyle *Some species have traits only during embryonic development All chordates share 5 characteristics… #1 Endostyle Notocord= longitudinal, flexible rod between the digestive tube and nerve cord, provides skeletal support © 2017 Pearson Education, Inc. All chordates share 5 characteristics… #2 #1 Endostyle Nerve Cord= develops into the central nervous system: brain & spinal cord © 2017 Pearson Education, Inc. All chordates share 5 characteristics… #2 #1 Endostyle #3 Pharyngeal Slits/Clefts: grooves form along outer surface of pharynx Suspension-feeding structures, gas exchange structures, or parts of ear and neck in tetrapods © 2017 Pearson Education, Inc. All chordates share 5 characteristics… #2 #4 #1 Endostyle #3 Muscular Post-Anal Tail: contains skeletal elements and muscles In many species, the tail is greatly reduced during embryonic development © 2017 Pearson Education, Inc. All chordates share 5 characteristics… #2 #4 #1 #5 Endostyle #3 The endostyle is a strip of ciliated mucus-producing tissue in the floor of the pharynx= food particles trapped in the mucus are moved along the endostyle toward the gut. Also produces substances similar to thyroid hormones and is homologous with the thyroid gland in vertebrates. © 2017 Pearson Education, Inc. Lancelets (Cephalochordata) named for bladelike shape • Marine suspension feeders • Retain characteristics of chordate body plan as adults 1 cm Cirri Mouth Notochord Pharyngeal slits Dorsal, hollow nerve cord Atrium Digestive tract Ancestral chordates may have Atriopore resembled lancelets: Segmental same Hox genes organize the muscles Anus vertebrate brain are expressed in lancelet’s nerve cord tip Tail © 2017 Pearson Education, Inc. Tunicates (Urochordata): more closely related to other chordates than lancelets • resemble chordates during larval stage, may last only a few minutes for some species Incurrent Water flow Notochord siphon to mouth Excurrent Dorsal, hollow siphon nerve cord Tail Excurrent Excurrent siphon siphon Atrium Muscle Incurrent segments siphon Pharynx Intestine with numerous Anus Stomach slits Intestine Atrium Tunic Esophagus Pharynx with slits Stomach (a) A tunicate larva (b) An adult tunicate (c) An adult tunicate Vertebrates are chordates with a backbone ▪ 2+ sets of Hox genes ▪ lancelets and tunicates have only one ▪ Most vertebrates- vertebrae enclose spinal cord and taken role of notochord ▪ Neural crest- cells develop along edge of neural tube of an embryo, develop into nerves, cardiovascular tissue, facial structures ▪ Skeletal system and complex nervous system increased effectiveness of… ▪ Capturing food ▪ Evading predators SuperclassFigure 34.8 Agnatha: Earliest vertebrates did not have jaws • 2 jawless vertebrate lineages today: Myxini: hagfishes & Petromyzontida: lampreys • Lack a true backbone • Rudimentary vertebrae & phylogenetic analysis support them as vertebrates Hagfishes: marine; most bottom-dwelling Lampreys: marine & freshwater habitats scavengers • Parasites- feed by clamping mouths onto a live fish • produce slime to repel competitors and • Free-living species- feed as larvae for years, then predators mature, reproduce, and die within a few days Slime Parasite Mouth glands © 2017 Pearson Education, Inc. Gnathostomes are vertebrates with jaws ▪ Earliest gnathostomes ~440 mya ▪ Fins developed bony structures, provided thrust & steering control for pursuit of prey & avoidance of predators • Characters common to gnathostomes: • Genome duplication, including duplication of Hox genes • Enlarged forebrain associated with enhanced senses of smell and vision • Lateral line system: rows of organs sensitive to vibrations along each side of body of aquatic gnathostomes • Today, gnathostomes, include sharks, fishes, amphibians, reptiles, birds, & mammals © 2017 Pearson Education, Inc. Chondrichthyans: skeleton composed primarily of cartilage • Largest and most diverse Dorsal fins group includes the sharks, rays, and skates • Second group has few dozen species of Pelvic fins Pectoral fins ratfishes (a) Blacktip reef shark (Carcharhinus melanopterus) (b) Southern stingray (Dasyatis americana) (c) Spotted ratfish (Hydrolagus colliei) © 2017 Pearson Education, Inc. Figure 34.17 Majority of vertebrates are osteichthyans: animals with a bony endoskeleton Ray-finned fishes ~30,000 species Yellowfin tuna (Thunnus albacares) (Actinopterygii) include Red lionfish (Pterois nearly all familiar aquatic volitans) osteichthyans The fins, supported mainly by long, flexible rays, are modified for maneuvering, defense, and other functions Common sea horse Fine-spotted moray eel (Hippocampus (Gymnothorax dovii) ramulosus) Majority vertebrates are osteichthyans: animals with bony endoskeleton Lobe-Fins (Sarcopterygii): 3 living lineages ▪ Coelacanths (Actinistia): thought to be extinct until a living coelacanth was caught on coast of South Africa in 1938 ▪ Lungfishes (Dipnoi): found in Southern Hemisphere ▪ Gills are main organs for gas exchange, also surface to gulp air into lungs ▪ Tetrapods: group adapted to life on land © 2017 Pearson Education, Inc. Tetrapods are gnathostomes with 4 limbs ▪ Adaptations ▪ Four limbs and feet with digits ▪ Neck: allows separate movement of head ▪ Fusion of pelvic girdle to backbone ▪ Absence of gills ▪ except some aquatic species ▪ Ears for detecting airborne sounds © 2017 Pearson Education, Inc. Amphibians (class Salamanders (Urodela): amphibians with tails Amphibia) are • Aquatic and terrestrial represented by about 6,150 species in three clades (a) Order Urodela Frogs (Anura): lack tails • Aquatic and terrestrial (b) Order Anura Caecilians (Apoda): legless, nearly blind • Absence of legs is secondary adaptation (c) Order Apoda © 2017 Pearson Education, Inc. Figure 34.23 (a) The tadpole (b) During metamorphosis Amphibian means “both ways of life,” referring to the metamorphosis of an aquatic larva into a terrestrial adult Larval stage of a frog= aquatic herbivore with gills, lateral line, tail During metamorphosis= develops legs, lungs, a pair of external eardrums, and a carnivorous digestive system (c) The adults return to water to mate Amniotes are Extraembryonic membranes tetrapods that have a Allantois Chorion terrestrially adapted egg Embryo Reptiles, Birds, Amniotic cavity Mammals with amniotic fluid Yolk (nutrients) Amnion= encloses embryo in fluid-filled sac, Albumen allows tetrapods to reproduce on Shell land Amnion Yolk sac Extraembryonic membranes (a) Tuatara (Sphenodon punctatus) Adaptations for Terrestrial Life Reptiles • Scales create a waterproof barrier • Shelled eggs • Internal fertilization (c) Wagler’s pit viper (b) Australian thorny devil lizard (Tropidolaemus wagleri) (Moloch horridus) Most reptiles are ectothermic (d) Black-breasted hill turtle (Geomyda spengleri) (e) American alligator (Alligator mississippiensis) Evolution of Birds Wing claw (~160 mya) Toothed beak Archaeopteryx: oldest bird known Had feathered wings, but retained ancestral reptile characters: teeth, claws, long tail Airfoil wing with contour feathers Long tail with many vertebrae Derived Characters of Birds ▪ Endothermic ▪ Adaptations for flight: ▪ Wings with keratin feathers ▪ Improved vision ▪ Fine muscle control ▪ Weight-saving adaptations: ▪ Loss of bladder ▪ One ovary in females ▪ Small gonads ▪ Loss of teeth ▪ Flight benefits: improved hunting & scavenging, escape from predators, and migration ▪ But..requires great expenditure of energy Not all birds fly… Bird Reproduction ▪ Birds generally display complex behaviors including elaborate courtship rituals ▪ Fertilization is internal ▪ Eggs and the developing embryos inside must be kept warm through brooding by one or both parents Mammals are amniotes that have hair Monotremes and produce milk Derived Characters of Mammals ▪ Mammary glands ▪ Endothermy ▪ Hair and a fat layer under skin Marsupials ▪ Kidneys ▪ Efficient respiratory and circulatory systems ▪ Large brain-to-body-size ratio ▪ Extensive parental care Eutherians ▪ Differentiated teeth © 2017 Pearson Education, Inc. Monotremes ▪ Egg-laying mammals ▪ Females lack nipples, secrete milk from glands on their bellies Platypus Echidnas © 2017 Pearson Education, Inc. Marsupials Embryo develops in mother’s uterus, nourished by placenta Offspring born early in development, completes development while nursing in a maternal pouch called a marsupium © 2017 Pearson Education, Inc. Eutherians (Placental Mammals) ▪ Young eutherians complete their embryonic development within a uterus, joined to the mother by the placenta © 2017 Pearson Education, Inc. Lemurs, lorises, and bush babies ANCESTRAL Tarsiers PRIMATE New World monkeys Anthropoids Old World monkeys Gibbons Orangutans Derived Characters of Primates • Hands and feet adapted for grasping, flat Gorillas nails instead of claws Chimpanzees • Large brain, short jaws and bonobos • Forward-looking eyes close together on the †Australopithecus face, providing depth perception Humans and • Fully opposable thumb (monkeys, apes) extinct Homo species 70 60 50 40 30 20 10 0 Time (millions of years ago) Monkeys (a) New World monkey: spider monkey Found in central and south America (b) Old world monkey: macaque Found