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Chapter 34

VERTEBRATES. Chapter 34. Vertebrates get their name from vertebrae, the series of bones that make up the backbone. • Phylum Chordata : (3 subdivisions) - Cephalochordata - lancelets (no backbone) - Urochordata - tunicates (no backbone)

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Chapter 34

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  1. VERTEBRATES Chapter 34

  2. Vertebrates get their name from vertebrae, the series of bones that make up the backbone • Phylum Chordata: (3 subdivisions) - Cephalochordata- lancelets (no backbone) - Urochordata- tunicates (no backbone) - Craniata/Vertebrata- vertebrates (skull, backbone, brain, eyes, etc)

  3. Fig. 34-2 Echinodermata (sister group to chordates) Cephalochordata (lancelets) ANCESTRAL DEUTERO- STOME Chordates Urochordata (tunicates) Notochord Myxini (hagfishes) Common ancestor of chordates Craniates Petromyzontida (lampreys) Head Vertebrates Chondrichthyes (sharks, rays, chimaeras) Vertebral column Actinopterygii (ray-finned fishes) Gnathostomes Jaws, mineralized skeleton Actinistia (coelacanths) Osteichthyans Lungs or lung derivatives Lobe-fins Dipnoi (lungfishes) Lobed fins Amphibia (frogs, salamanders) Tetrapods Reptilia (turtles, snakes, crocodiles, birds) Legs Amniotes Amniotic egg Mammalia (mammals) Milk

  4. Derived Characters of Chordates • All chordates share a set of derived characters • Some species have some of these traits only during embryonic development • Notochord - a longitudinal, flexible rod between the digestive tube and nerve cord; provides skeletal support • In most vertebrates, a more complex, jointed skeleton develops, and the adult retains only remnants of the mbryonic notochord • Dorsal, hollow nerve cord - develops into the central nervous system: the brain and the spinal cord • Pharyngeal slits or clefts – gas exchange (vertebrates), develop into parts of the ear, head, and neck (tetrapods), suspension feeding (invertebrates) • Muscular, post-anal tail -

  5. Fig. 34-3 Dorsal, hollow nerve cord Muscle segments Notochord Mouth Anus Pharyngeal slits or clefts Muscular, post-anal tail

  6. Craniates are chordates that have a head • The origin of a head opened up a completely new way of feeding for chordates: active predation • Craniates share some characteristics: a skull, brain, eyes, and other sensory organs • Also know as subphylum Vertebrata

  7. Derived Characters of Craniates/Vertebrata • One feature unique to craniates is the neural crest, a collection of cells near the dorsal margins of the closing neural tube in an embryo • Neural crest cells give rise to a variety of structures, including some of the bones and cartilage of the skull • In aquatic craniates the pharyngeal clefts evolved into gill slits • Craniates have a heart with at least two chambers, red blood cells with hemoglobin, and kidneys

  8. Fig. 34-7 Neural crest Neural tube Dorsal edges of neural plate Migrating neural crest cells Notochord

  9. SUPERCLASS AGNATHA = jawless fish • Myxini, the hagfishes lack jaws and vertebrate • Petromyzontida, the lampreys lack jaws but have a vertebrate

  10. Fig. 34-9 Slime glands Hagfish Video: Lamprey Lamprey

  11. Derived Characters of Vertebrates • Vertebrates = Craniates with a back bone • Vertebrates have the following derived characters: • Vertebrae enclosing a spinal cord • An elaborate skull • Fin rays, in the aquatic forms

  12. SUPERCLASS Gnathostomes are vertebrates that have jaws • Jawed vertebrates (gnathostomes) outnumber jawless vertebrates • An enlarged forebrain associated with enhanced smell and vision

  13. CLASS Chondrichthyans (Sharks, Rays, and Their Relatives) • Chondrichthyans (Chondrichthyes) have a skeleton composed primarily of cartilage • The cartilaginous skeleton evolved secondarily from an ancestral mineralized skeleton • The largest and most diverse group of chondrichthyans includes the sharks, rays, and skates Video: Shark and rays Video: Manta Ray Video: Shark and rays

  14. Fig. 34-15 Pelvicfins Pectoral fins (a) Blacktip reef shark (Carcharhinus melanopterus) (b) Southern stingray (Dasyatis americana) (c) Spotted ratfish (Hydrolagus colliei)

  15. Sharks: • Have a streamlined body and are swift swimmers • Are carnivores • Have a short digestive tract • Have acute senses • Shark eggs are fertilized internally but embryos can develop in different ways: • Oviparous: eggs hatch outside the mother’s body • Ovoviviparous: the embryo develops within the uterus and is nourished by the egg yolk • Viviparous: the embryo develops within the uterus and is nourished through a yolk sac placenta from the mother’s blood

  16. CLASS Osteichthyes (Ray-Finned Fishes and Lobe-Fins) • Nearly all living osteichthyans have a bony endoskeleton • Aquatic osteichthyans are the vertebrates we informally call fishes • Most fishes breathe by drawing water over gills protected by an operculum • Fishes control their buoyancy with an air sac known as a swim bladder

  17. CLASS Osteichthyes 2 Subdivisions: • Clade Actinopterygii- ray finned fishes, the fins are supported mainly by long, flexible rays, and are modified for maneuvering, defense, and other functions • Clade Sarcopterygii- lobe fin fishes, have muscular pelvic and pectoral fins • Actinistia (coelacanths)- ancient lineage of lobe fin fishes; currently found in Indian Ocean • Clade Dipnoi (lungfish)- freshwater lobe fins with gills and lungs (sister group to tetrapods)

  18. Fig. 34-17 Ray finned fishes (a) Yellowfin tuna (Thunnus albacares) Video: Sea horse (b) Clownfish (Amphiprion ocellaris) Video: Eel (d) Fine-spotted moray eel (Gymnothorax dovii) (c) Sea horse (Hippocampus      ramulosus)

  19. Fig. 34-18 Lobe fin fishes Video: Coelacanth

  20. Tetrapods are gnathostomes (have jaws) that have limbs • Fins of some lobe-fins evolved into the limbs and feet of tetrapods Derived Characters of Tetrapods • •Tetrapods have some specific adaptations: • - Four limbs, and feet with digits • - Ears for detecting airborne sounds

  21. Fig. 34-21 CLASS Amphibia = Amphibians • Amphibians are represented by about 6,150 species of organisms in three orders • Order Urodela includes salamanders, which have tails • Order Anura includes frogs and toads, which lack tails • Order Apoda includes caecilians, which are legless and resemble worms (a) Order Urodela (b) Order Anura (c) Order Apoda

  22. Fig. 34-22 (c) Mating adults (b) During metamorphosis (a) Tadpole • Amphibian means “both ways of life,” referring to the metamorphosis of an aquatic larva into a terrestrial adult • Most amphibians have moist skin that complements the lungs in gas exchange • Fertilization is external in most species, and the eggs require a moist environment Video: Tadpole to frog

  23. Amniotes are tetrapods that have a terrestrially adapted egg • Amniotes are a group of tetrapods whose living members are the reptiles, including birds, and mammals

  24. Fig. 34-24 Parareptiles Turtles Crocodilians Reptiles Pterosaurs Archosaurs Ornithischian dinosaurs Dinosaurs Saurischian dinosaurs other than birds Diapsids Saurischians Birds Plesiosaurs ANCESTRAL AMNIOTE Ichthyosaurs Tuataras Lepidosaurs Squamates Mammals Synapsids

  25. Derived Characters of Amniotes • Amniotes are named for the major derived character of the clade, the amniotic egg, which contains membranes that protect the embryo • The extraembryonic membranes are the amnion, chorion, yolk sac, and allantois • Amniotes have other terrestrial adaptations, such as relatively impermeable skin and the ability to use the rib cage to ventilate the lungs • Class Reptilia, Aves, Mammalia

  26. Fig. 34-25 Chorion Allantois Yolk sac Amnion Embryo Amniotic cavity with amniotic fluid Yolk (nutrients) Albumen Shell

  27. CLASS Reptilia • The reptile class includes the tuataras, lizards, snakes, turtles, crocodilians, and the extinct dinosaurs • Reptiles have scales that create a waterproof barrier • They lay shelled eggs on land

  28. Most reptiles are ectothermic, absorbing external heat as the main source of body heat (cold blooded) • Birds are endothermic, capable of keeping the body warm through metabolism (warm blooded)

  29. • Order Squamata - Lizards and snakes • OrderSphenodontia - Tuataras CLASS REPTILIA (b) Australian thorny devil lizard (Moloch horridus) (a) Tuatara (Sphenodon punctatus) • Snakes are legless lepidosaurs (lizard ancestor) (c) Wagler’s pit viper (Tropidolaemus wagleri) Video: Snake Ritual Wrestling Video: Galapagos iguana

  30. Turtles are the most distinctive group of reptiles alive today All turtles have a boxlike shell made of upper and lower shields that are fused to the vertebrae, clavicles, and ribs Archosaurs gave rise to this order (dinosaurs) Crocodilians (alligators and crocodiles) Order Crocodilia = Alligators & Crocodiles Order Testudines = Turtles and Tortoise (e) American alligator (Alligator mississippiensis) (d) Eastern box turtle (Terrapene carolina carolina) Video: Galápagos Tortoise

  31. CLASS AVES = Birds • Birds = every feature of their reptilian anatomy has undergone modification in their adaptation to flight • Many characters of birds are adaptations that facilitate flight • The major adaptation is wings with keratin feathers • Other adaptations include lack of a urinary bladder, females with only one ovary, small gonads, and loss of teeth

  32. Fig. 34-28 Finger 1 (b) Bone structure Palm (a) Wing Finger2 Finger3 Forearm Wrist Shaft Shaft Barb Vane Barbule Hook (c) Feather structure

  33. Flight enhances hunting and scavenging, escape from terrestrial predators, and migration • Flight requires a great expenditure of energy, acute vision, and fine muscle control The Origin of Birds • Birds probably descended from small theropods, a group of carnivorous dinosaurs

  34. Living Birds Several groups of birds are flightless • The ratites, order Struthioniformes • Penguins, order Sphenisciformes • Certain species of rails, ducks, and pigeons • The demands of flight have rendered the general body form of many flying birds similar to one another • Foot structure in birds shows considerable variation

  35. Fig. 34-30 (a) Emu (b) Mallards (c) Laysan albatrosses (d) Barn swallows

  36. CLASS MAMMALIA • Mammals are amniotes that have: • Mammary glands, which produce milk • Hair • A larger brain than other vertebrates of equivalent size • Differentiated teeth

  37. By the early Cretaceous, the three living lineages of mammals emerged: • Monotremes- egg-laying mammals consisting of echidnas and the platypus • Marsupials- opossums, kangaroos, and koalas • Eutherians- Compared with marsupials, thesehave a longer period of pregnancy

  38. Fig. 34-32 Monotremes

  39. Marsupials • The embryo develops within a placenta in the mother’s uterus • A marsupial is born very early in its development • It completes its embryonic development while nursing in a maternal pouch called a marsupium (a) A young brushtail possum Video: Koala (b) Long-nosed bandicoot

  40. Eutherians (Placental Mammals) • Compared with marsupials, eutherians have a longer period of pregnancy • Young eutherians complete their embryonic development within a uterus, joined to the mother by the placenta • All other vertebrates

  41. Fig. 34-35a Monotremata Monotremes (5 species) Marsupialia ANCESTRAL MAMMAL Marsupials (324 species) Proboscidea Sirenia Tubulidentata Hyracoidea Afrosoricida (golden moles and tenrecs) Macroscelidea (elephant shrews) Eutherians (5,010 species) Xenarthra Rodentia Lagomorpha Primates Dermoptera(flyinglemurs) Scandentia(treeshrews) Carnivora Cetartiodactyla Perissodactyla Chiroptera Eulipotyphla Pholidota (pangolins)

  42. Fig. 34-35b

  43. Order Primates • The mammalian order Primates includes lemurs, tarsiers, monkeys, and apes • Humans are members of the ape group

  44. Derived Characters of Primates • Other derived characters of primates: • A large brain and short jaws • Forward-looking eyes close together on the face, providing depth perception • Complex social behavior and parental care • A fully opposable thumb (in monkeys and apes)

  45. Living Primates • There are three main groups of living primates: • Lemurs, lorises, and pottos • Tarsiers • Anthropoids (monkeys and apes) • The first monkeys evolved in the Old World (Africa and Asia) • In the New World (South America), monkeys first appeared roughly 25 million years ago

  46. Fig. 34-37 Lemurs, lorises, and pottos Tarsiers ANCESTRAL PRIMATE New World monkeys Anthropoids Old World monkeys Gibbons Orangutans Gorillas Chimpanzees and bonobos Humans 40 60 50 20 10 30 0 Time (millions of years ago)

  47. Fig. 34-39 (a) Gibbon (b) Orangutan Video: Gibbons Brachiating Video: Chimp Cracking Nut (c) Gorilla Video: Howler monkey calling (d) Chimpanzees (e) Bonobos

  48. Humans are mammals that have a large brain and bipedal locomotion • A number of characters distinguish humans from other apes: • Upright posture and bipedal locomotion • Larger brains • Language capabilities and symbolic thought • The manufacture and use of complex tools • Shortened jaw • Shorter digestive tract

  49. The Earliest Hominins and Australopiths • The study of human origins is known as paleoanthropology • Early hominins/hominids (originated in Africa) had a small brain but probably walked upright • “Robust” australopiths had sturdy skulls and powerful jaws • “Gracile” australopiths were more slender and had lighter jaws

  50. Fig. 34-41 (a) Australopithecus afarensis skeleton (b)The Laetolifootprints (c) An artist’s reconstruction of what A. afarensis may have looked like

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