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Ap Chap 34 The Vertebrates
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Ap Chap 34 The Vertebrates

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  • 1. AP Bio Chapter 34
  • 2. Overview: Half a Billion Years of Backbones
    • Early in the Cambrian period, about 530 million years ago, an astonishing variety of animals inhabited Earth’s oceans
    • One type of animal gave rise to vertebrates, one of the most successful groups of animals
  • 3.
    • The animals called vertebrates get their name from vertebrae, the series of bones that make up the backbone
    • There are about 52,000 species of vertebrates, including the largest organisms ever to live on the Earth
    • Vertebrates have great disparity , a wide range of differences within the group
  • 4. Vertebrates belong to the phylum CHORDATA
    • Other groups in the chordates:
    • Urochordates (tunicates)
    • Cephalochordates (lancelets)
    • Hagfishes
    • Lampreys
  • 5.
    • They are DEUTEROSTOMES along with the echinoderms
  • 6. Fig. 34-2 Lobed fins Legs Amniotic egg Milk Jaws, mineralized skeleton Lungs or lung derivatives Vertebral column Head Notochord Common ancestor of chordates ANCESTRAL DEUTERO- STOME Echinodermata (sister group to chordates) Chondrichthyes (sharks, rays, chimaeras) Cephalochordata (lancelets) Urochordata (tunicates) Myxini (hagfishes) Petromyzontida (lampreys) Mammalia (mammals) Actinopterygii (ray-finned fishes) Actinistia (coelacanths) Amphibia (frogs, salamanders) Dipnoi (lungfishes) Reptilia (turtles, snakes, crocodiles, birds) Chordates Craniates Vertebrates Gnathostomes Lobe-fins Osteichthyans Tetrapods Amniotes
  • 7. Derived Characters of Chordates
    • All chordates share a set of derived characters
    • Some species have some of these traits only during embryonic development
    • Four key characters of chordates:
      • Notochord
      • Dorsal, hollow nerve cord
      • Pharyngeal slits or clefts
      • Muscular, post-anal tail
  • 8. Fig. 34-3 Dorsal, hollow nerve cord Anus Muscular, post-anal tail Pharyngeal slits or clefts Notochord Mouth Muscle segments
  • 9. What happens to those characteristics in higher chordates such as us?
    • Notochord becomes intervertebral cartilaginous disks
    • Nerve cord stays the same
    • Pharyngeal slits initially used for suspension feeding and respiratory structures become ear, neck, and jaw parts
    • Tails - gone
  • 10. Lancelets
    • Lancelets (Cephalochordata) are named for their bladelike shape
    • They are marine suspension feeders that retain characteristics of the chordate body plan as adults
  • 11. Fig. 34-4 Dorsal, hollow nerve cord Notochord Tail Cirri Mouth Pharyngeal slits Digestive tract Atrium Atriopore Segmental muscles Anus 2 cm
  • 12. Tunicates
    • Tunicates (Urochordata) are more closely related to other chordates than are lancelets during their larval stage.
    • They are marine suspension feeders commonly called sea squirts
    • As an adult, a tunicate draws in water through an incurrent siphon , filtering food particles
  • 13. Fig. 34-5 Tunic Water flow Excurrent siphon Atrium An adult tunicate Pharynx with slits Anus Atrium Excurrent siphon Incurrent siphon to mouth Dorsal, hollow nerve cord Incurrent siphon Excurrent siphon Muscle segments Notochord Tail Stomach Intestine Intestine Esophagus Stomach Pharynx with slits A tunicate larva
  • 14. Early Chordate Evolution
    • Ancestral chordates may have resembled lancelets
    • Genome sequencing of tunicates has identified genes shared by tunicates and vertebrates
    • Gene expression in lancelets holds clues to the evolution of the vertebrate form
  • 15. Fig. 34-6 BF1 Brain of vertebrate embryo (shown straightened) Hindbrain Forebrain Midbrain Nerve cord of lancelet embryo BF1 Hox3 Otx Otx Hox3
  • 16. Derived Characters of Craniates
    • Craniates have two clusters of Hox genes ; lancelets and tunicates have only one cluster
    • Neural crest cells that become teeth and bones of skull
    • Paryngeal clefts become gill slits
    • High metabolism, 2 or more chambered hearts, rbc’s with hemoglobin, kidneys
  • 17. Fig. 34-7 Migrating neural crest cells Notochord Dorsal edges of neural plate Neural crest Neural tube
  • 18. Hagfishes
    • The least derived surviving craniate
    • Hagfishes have a cartilaginous skull derived from the notochord, but lack jaws and vertebrae
    • They are scavengers and slimy!
  • 19. Fig. 34-9 Slime glands
  • 20. Vertebrates are craniates that have a backbone
    • During the Cambrian period, a lineage of craniates evolved into vertebrates
    • Vertebrates became more efficient at capturing food and avoiding being eaten
    • Vertebrates have the following derived characters:
      • Vertebrae enclosing a spinal cord
      • An elaborate skull
      • Fin rays, in the aquatic forms
  • 21. Lampreys
    • Lampreys represent the oldest living lineage of vertebrates
    • They are jawless vertebrates inhabiting various marine and freshwater habitats
    • They have cartilaginous segments surrounding the notochord and arching partly over the nerve cord
  • 22. Fig. 34-10
  • 23. Fossils of Early Vertebrates
    • Conodonts were the first vertebrates with mineralized skeletal elements in their mouth and pharynx
  • 24. Fig. 34-11 Dental elements
  • 25. Other armored, jawless vertebrates had defensive plates of bone on their skin Fig. 34-12 Pteraspis Pharyngolepis
  • 26. Origins of Bone, Teeth, and Jaws
    • Mineralization appears to have originated with vertebrate mouthparts
    • The vertebrate endoskeleton became fully mineralized much later
    • Today, jawed vertebrates, or gnathostomes, outnumber jawless vertebrates
  • 27. Derived Characters of Gnathostomes
    • Gnathostomes have jaws that might have evolved from skeletal supports of the pharyngeal slits
      • An additional duplication of Hox genes
      • An enlarged forebrain associated with enhanced smell and vision
      • In aquatic gnathostomes, the lateral line system, which is sensitive to vibrations
  • 28. Fig. 34-13-3 Skeletal rods Cranium Gill slits Mouth
  • 29. Fig. 34-14 0.5 m
  • 30. 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: Manta Ray
  • 31. Fig. 34-15 Pelvic fins Pectoral fins (c) Spotted ratfish ( Hydrolagus colliei ) (a) Blacktip reef shark ( Carcharhinus       melanopterus ) (b) Southern stingray ( Dasyatis americana )
  • 32.
    • Most sharks
      • Have a streamlined body and are swift swimmers
      • Are carnivores
      • Have a short digestive tract; a ridge called the spiral valve increases the digestive surface area
      • Have acute senses
  • 33. Spiral valve in sharks
  • 34.
    • 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
  • 35.
    • The reproductive tract, excretory system, and digestive tract empty into a common cloaca
  • 36. Ray-Finned Fishes and Lobe-Fins
    • The vast majority of vertebrates belong to a clade of gnathostomes called Osteichthyes
    • Osteichthyes includes the bony fish and tetrapods
  • 37.
    • 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
  • 38. Fig. 34-16 Intestine Adipose fin (characteristic of trout) Cut edge of operculum Swim bladder Caudal fin Lateral line Urinary bladder Pelvic fin Anus Dorsal fin Spinal cord Brain Nostril Gills Kidney Heart Liver Gonad Anal fin Stomach
  • 39. Ray-Finned Fishes
    • The ray-finned fishes , includes nearly all the familiar aquatic osteichthyans
    • The fins, supported mainly by long, flexible rays, are modified for maneuvering, defense, and other functions
    Video: Clownfish and Anemone Video: Coral Reef
  • 40. Fig. 34-17 (a) Yellowfin tuna ( Thunnus albacares ) (b) Clownfish ( Amphiprion ocellaris ) (c) Sea horse ( Hippocampus       ramulosus ) (d) Fine-spotted moray eel ( Gymnothorax dovii )
  • 41. Lobe-Fins
    • The lobe-fins (Sarcopterygii) have muscular pelvic and pectoral fins
    • Three lineages survive and include coelacanths, lungfishes, and tetrapods
  • 42. Fig. 34-18
  • 43. Tetrapods are gnathostomes that have limbs
    • One of the most significant events in vertebrate history was when the fins of some lobe-fins evolved into the limbs and feet of tetrapods
    • Tetrapods have some specific adaptations:
      • Four limbs, and feet with digits
      • Ears for detecting airborne sounds
  • 44. Fig. 34-19 Tetrapod limb skeleton Bones supporting gills
  • 45. Amphibians
    • Amphibians (class Amphibia) are represented by about 6,150 species
    • 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
  • 46. 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
    • The extraembryonic membranes are the
    • amnion (provide watery environment),
    • chorion (gas exchange),
    • yolk sac (nourishment), and
    • allantois (waste removal)
    • Amniotes have other terrestrial adaptations, such as relatively impermeable skin and the ability to use the rib cage to ventilate the lungs
  • 47. Fig. 34-25 Yolk sac Amniotic cavity with amniotic fluid Chorion Amnion Albumen Yolk (nutrients) Allantois Embryo Shell
  • 48. Reptiles
    • The reptile clade includes the tuataras, lizards, snakes, turtles, crocodilians, birds, and the extinct dinosaurs
    • Reptiles have scales that create a waterproof barrier
    • They lay shelled eggs on land
    • Most reptiles are ectothermic, absorbing external heat as the main source of body heat
    • Birds are endothermic, capable of keeping the body warm through metabolism
  • 49. Fig. 34-27 (a) Tuatara ( Sphenodon punctatus ) (c) Wagler’s pit viper ( Tropidolaemus wagleri ) (b) Australian thorny devil lizard ( Moloch horridus ) (e) American alligator ( Alligator mississippiensis ) (d) Eastern box turtle ( Terrapene carolina carolina )
  • 50. Where are the birds now?
    • Birds are archosaurs, but almost every feature of their reptilian anatomy has undergone modification in their adaptation to flight
  • 51. Fig. 34-26
  • 52.
    • 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, hollow bones, and loss of teeth
    Derived Characters of Birds
  • 53. Fig. 34-28 (a) Wing (b) Bone structure (c) Feather structure Finger 1 Finger 2 Finger 3 Palm Hook Vane Barbule Barb Shaft Wrist Forearm Shaft
  • 54.
    • Birds probably descended from small theropods, a group of carnivorous dinosaurs
    • By 150 million years ago, feathered theropods had evolved into birds
    • Archaeopteryx remains the oldest bird known
    The Origin of Birds
  • 55. Fig. 34-29 Airfoil wing with contour feathers Toothed beak Wing claw Long tail with many vertebrae
  • 56. Fig. 34-30 (a) Emu (b) Mallards (c) Laysan albatrosses (d) Barn swallows
  • 57. Mammals are amniotes that have hair and produce milk
    • Mammals , class Mammalia, are represented by more than 5,300 species
  • 58. Derived Characters of Mammals
    • Mammals have
      • Mammary glands, which produce milk
      • Hair
      • A larger brain than other vertebrates of equivalent size
      • Differentiated teeth
  • 59. Monotremes
    • Monotremes are a small group of egg-laying mammals consisting of echidnas and the platypus
  • 60. Fig. 34-32
  • 61. Marsupials
    • Marsupials include opossums, kangaroos, and koalas
    • 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
  • 62. Fig. 34-33 (a) A young brushtail possum (b) Long-nosed bandicoot
  • 63. Fig. 34-34 Plantigale Marsupial mammals Eutherian mammals Marsupial mammals Eutherian mammals Marsupial mole Flying squirrel Sugar glider Deer mouse Mole Tasmanian devil Wombat Kangaroo Woodchuck Patagonian cavy Wolverine
  • 64. 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
    • Molecular and morphological data give conflicting dates on the diversification of eutherians
  • 65. Fig. 34-35b