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Chapter 34

Chapter 34. Vertebrates. Figure 34.1. Overview:. The animals called vertebrates Get their name from vertebrae, the series of bones that make up the backbone. Dorsal, hollow nerve cord. Brain. Notochord. Muscle segments. Mouth. Anus. Pharyngeal slits or clefts. Muscular, post-anal tail.

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Chapter 34

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  1. Chapter 34 Vertebrates

  2. Figure 34.1 Overview: • The animals called vertebrates • Get their name from vertebrae, the series of bones that make up the backbone

  3. Dorsal,hollownerve cord Brain Notochord Musclesegments Mouth Anus Pharyngealslits or clefts Muscular,post-anal tail Figure 34.3 Concept 34.1: Derived Characters of Chordates • All chordates share a set of derived characters • Although some species possess some of these traits only during embryonic development

  4. Notochord • The notochord • Is a longitudinal, flexible rod located between the digestive tube and the nerve cord • Provides skeletal support throughout most of the length of a chordate • In most vertebrates, a more complex, jointed skeleton develops • And the adult retains only remnants of the embryonic notochord

  5. Dorsal, Hollow Nerve Cord • The nerve cord of a chordate embryo • Develops from a plate of ectoderm that rolls into a tube dorsal to the notochord • Develops into the central nervous system: the brain and the spinal cord

  6. Pharyngeal Slits or Clefts • In most chordates, grooves in the pharynx called pharyngeal clefts • Develop into slits that open to the outside of the body • These pharyngeal slits • Are modified for gas exchange in aquatic vertebrates • Develop into parts of the ear, head, and neck in terrestrial vertebrates

  7. Muscular, Post-Anal Tail • Chordates have a tail extending posterior to the anus • Although in many species it is lost during embryonic development • The chordate tail contains skeletal elements and muscles • And it provides much of the propelling force in many aquatic species

  8. Concept 34.2: • 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 common characteristics • A skull, brain, eyes, and other sensory organs

  9. Concept 34.3: • Vertebrates are craniates that have a backbone • Vertebrates have • Vertebrae enclosing a spinal cord • An elaborate skull • Fin rays, in aquatic forms

  10. Lampreys • Lampreys, class Cephalaspidomorphi • Represent the oldest living lineage of vertebrates • Have cartilaginous segments surrounding the notochord and arching partly over the nerve cord

  11. Figure 34.10 • Lampreys are jawless vertebrates • Inhabiting various marine and freshwater habitats

  12. Concept 34.4: • Gnathostomes are vertebrates that have jaws • Today, jawless vertebrates • Are far outnumbered by those with jaws

  13. Other characters common to gnathostomes include • Enhanced sensory systems, including the lateral line system • An extensively mineralized endoskeleton • Paired appendages

  14. Chondrichthyans (Sharks, Rays, and Their Relatives) • Members of class Chondrichthyes • Have a skeleton that is composed primarily of cartilage • The cartilaginous skeleton • Evolved secondarily from an ancestral mineralized skeleton

  15. (a) Blacktip reef shark (Carcharhinus melanopterus).Fast swimmers with acute senses, sharks have paired pectoral and pelvic fins. Pelvic fins Pectoral fins (b) Southern stingray (Dasyatis americana).Most rays are flattened bottom-dwellers thatcrush molluscs and crustaceans for food. Some rays cruise in open water and scoop food into their gaping mouth. Figure 34.15a, b • The largest and most diverse subclass of Chondrichthyes • Includes the sharks and rays

  16. Ray-Finned Fishes and Lobe-Fins • The vast majority of vertebrates • Belong to a clade of gnathostomes called Osteichthyes

  17. Nearly all living osteichthyans • Have a bony endoskeleton • Aquatic osteichthyans • Are the vertebrates we informally call fishes • Control their buoyancy with an air sac known as a swim bladder

  18. Adipose fin(characteristic oftrout) Dorsal fin Caudal fin Swim bladder Spinal cord Brain Nostril Cut edge of operculum Anal fin Gills Anus Gonad Liver Heart Lateral line Stomach Urinary bladder Kidney Intestine Pelvic fin Figure 34.16 • Fishes breathe by drawing water over four or five pairs of gills

  19. (a) Yellowfin tuna (Thunnus albacares), a fast-swimming, schooling fish that is an important commercial fish worldwide (b) Clownfish (Amphiprion ocellaris), a mutualistic symbiont of sea anemones (c) Sea horse (Hippocampus ramulosus), unusual in the animal kingdom in that the male carries the young during their embryonic development (d) Fine-spotted moray eel (Gymnothorax dovii), a predator that ambushes prey from crevices in its coral reef habitat Figure 34.17a–d Ray-Finned Fishes • The ray-finned fishes includes nearly all the familiar aquatic osteichthyans

  20. The fins, supported mainly by long, flexible rays • Are modified for maneuvering, defense, and other functions

  21. Figure 34.18 Lobe-Fins • The lobe-fins • Have muscle covering bones of their pelvic and pectoral fins • Include coelacanths, lungfishes, and tetrapods

  22. Concept 34.5: • Tetrapods are gnathostomes that have limbs and feet • 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

  23. Derived Characters of Tetrapods • Tetrapods have some specific adaptations • Four limbs and feet with digits • Ears for detecting airborne sounds

  24. Amphibians • Amphibians are represented by about 4,800 species of organisms • Most amphibians • Have moist skin that complements the lungs in gas exchange

  25. (a) salamanders retain their tail as adults. Figure 34.21a Amphibians • Includes salamanders, which have tails

  26. Figure 34.21b Amphibians • Includes frogs and toads, which lack tails as adults (b) poison arrow frog

  27. (c) Caecilians, mainly burrowing amphibians. Figure 34.21c Amphibians • Includes caecilians, which are legless and resemble worms

  28. (b) The tadpole is an aquatic herbivore witha fishlike tail and internal gills. (c) During metamorphosis, the gills and tail are resorbed, andwalking legs develop. (a) The male grasps the female, stimulating her to release eggs. The eggs are laid and fertilized in water. They have a jelly coat but lack a shell and would desiccate in air. Figure 34.22a–c Amphibians • Amphibian means “two lives” • A reference to the metamorphosis of an aquatic larva into a terrestrial adult

  29. Concept 34.6: • Amniotes are tetrapods that have a terrestrially adapted egg • Amniotes are a group of tetrapods • Whose living members are the reptiles, including birds, and the mammals

  30. Derived Characters of Amniotes • Amniotes are named for the major derived character of the clade, the amniotic egg • Which contains specialized membranes that protect the embryo

  31. Chorion. The chorion and the membrane of the allantois exchange gases between the embryo and the air. Oxygen and carbon dioxide diffuse freely across the shell. Allantois. The allantois is a disposal sac for certain metabolic wastes pro- duced by the embryo. The membrane of the allantois also functions with the chorion as a respiratory organ. Extraembryonic membranes Yolk sac. The yolk sac contains the yolk, a stockpile of nutrients. Blood vessels in the yolk sac membrane transport nutrients from the yolk into the embryo. Other nutrients are stored in the albumen (“egg white”). Amnion. The amnion protectsthe embryo in a fluid-filled cavity that cushions againstmechanical shock. Embryo Amniotic cavitywith amniotic fluid Yolk (nutrients) Albumen Shell Figure 34.24 • The extraembryonic membranes have various functions

  32. Amniotes also have other terrestrial adaptations • Such as relatively impermeable skin and the ability to use the rib cage to ventilate the lungs

  33. Reptiles • The reptile clade includes • The tuatara, lizards, snakes, turtles, crocodilians, birds, and the extinct dinosaurs

  34. Figure 34.25 • Reptiles • Have scales that create a waterproof barrier • Lay shelled eggs on land

  35. 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

  36. (a) Tuatara (Sphenodon punctatus) Figure 34.27a The Origin and Evolutionary Radiation of Reptiles • One surviving lineage of lepidosaurs • Is represented by two species of lizard-like reptiles called tuatara

  37. Figure 34.27b (b) Australian thorny devil lizard (Moloch horridus) • The other major living lineage of lepidosaurs • Are the squamates, the lizards and snakes • Lizards • Are the most numerous and diverse reptiles, apart from birds

  38. (c) Wagler’s pit viper (Tropidolaemus wagleri), a snake Figure 34.27c • Snakes are legless lepidosaurs • That evolved from lizards

  39. Turtles • Turtles • Are the most distinctive group of reptiles alive today • Some turtles have adapted to deserts • And others live entirely in ponds and rivers

  40. Figure 34.27d (d) Eastern box turtle (Terrapene carolina carolina) • All turtles have a boxlike shell • Made of upper and lower shields that are fused to the vertebrae, clavicles, and ribs

  41. Figure 34.27e (e) American alligator (Alligator mississipiensis) Alligators and Crocodiles • Crocodilians • Belong to a lineage that dates back about 200 million years

  42. Birds • Birds are archosaurs • But almost every feature of their reptilian anatomy has undergone modification in their adaptation to flight

  43. Finger 1 (b) Bone structure Palm (a) wing Finger 2 Forearm Wrist Finger 3 Shaft Vane Barb Shaft Barbule Hook Figure 34.28a–c (c) Feather structure Derived Characters of Birds • A bird’s most obvious adaptations for flight • Are its wings and feathers

  44. (a) Emu. This ratite lives in Australia. Figure 34.30a Living Birds • The ratites, order Struthioniformes • Are all flightless

  45. (b) Mallards. Like many bird species, the mallard exhibits pronounced color differences between the sexes. (c) Laysan albatrosses. Like most birds, Laysan albatrosses have specific mating behaviors, such as this courtship ritual. (d) Barn swallows. The barn swallow is a member of the order Passeriformes. Species in this order are called perching birds because the toes of their feet can lock around a branch or wire, enabling the bird to rest in place for long periods. Figure 34.30b–d • The demands of flight • Have rendered the general body form of many flying birds similar to one another

  46. Raptor(such as a bald eagle) Grasping bird (such as a woodpecker) Swimming bird(such as a duck) Perching bird (such as a cardinal) Figure 34.31 • Foot structure in bird feet • Shows considerable variation

  47. Concept 34.7: • Mammals are amniotes that have hair and produce milk • Mammals, class Mammalia • Are represented by more than 5,000 species

  48. Derived Characters of Mammals • Mammary glands, which produce milk are a distinctively mammalian character • Hair is another mammalian characteristic • Mammals generally have a larger brain than other vertebrates of equivalent size

  49. Figure 34.33 Monotremes • Monotremes • Are a small group of egg-laying mammals consisting of echidnas and the platypus

  50. Marsupials • Marsupials • Include opossums, kangaroos, and koalas

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