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19 Lecture Ppt

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  • 1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 19 Evolution of Animals
  • 2. Key Innovations Distinguish Invertebrate Groups 19-
  • 3. 19.1 Animals have distinctive characteristics
    • Animals are multicellular eukaryotes
      • Chemoheterotrophs that acquire nutrients from an external source and digest it internally
      • Usually carry on sexual reproduction and begin life only as a fertilized diploid egg
      • Developmental stages to produce specialized tissues within organs with specific functions
      • Muscles and nerves characterize animals
        • Allow animals to perform flexible movements
    19-
  • 4. Figure 19.1 Developmental stages of a frog 19-
  • 5. 19.2 Animals most likely have a protistan ancestor
    • Two hypotheses on origin of animals
      • Multinucleate Hypothesis
      • Animals arose from a ciliated protist in stages
        • The ciliate would have acquired multiple nuclei, and then it would have become multicellular
      • Colonial Flagellate Hypothesis
        • Animals descended from an ancestor that resembled a spherical colony of flagellated cells
    19-
  • 6. Figure 19.2 The colonial flagellate hypothesis 19-
  • 7. Radial and Bilateral Symmetry 19-
  • 8. 19.3 The traditional evolutionary tree of animals is based on seven key innovations (figure 19.3A) 19-
  • 9. Animal Body Cavities
    • Figure 19.3B Types of body cavity
    19-
  • 10. APPLYING THE CONCEPTS—HOW SCIENCE PROGRESSES 19.4 Molecular data suggest a new evolutionary tree for animals
    • In traditional tree, protostomes are restricted to three phyla, which have a coelom
      • Arthropods, Annelids, and Molluscs
    • Evolutionary tree based on molecular data suggests many more animal phyla should be designated protostomes because their rRNA sequences are so similar
      • Segmentation doesn’t play a defining role in the evolutionary tree based on molecular data
    19-
  • 11. Figure 19.4A Proposed new evolutionary tree 19-
  • 12. Figure 19.4B Roundworms and arthropods are molting animals 19-
  • 13. 19.5 Some animal groups are invertebrates and some are vertebrates
    • For convenience, the animal phyla have been divided into
      • Invertebrates - those that do not have an endoskeleton of cartilage and bone
      • Vertebrates - those that do have an endoskeleton
    • Animals evolved in the sea and most animals still live in the water
      • Among the invertebrates only the molluscs, annelids, and arthropods have terrestrial representatives
    19-
  • 14. 19-
  • 15. 19.6 Sponges are multicellular invertebrates
    • Only animal without true tissue, organized at cellular level
    • Body of Sponges - phylum Porifera because their bodies are perforated by pores
      • Filter feeder , also called a suspension feeder, because it filters suspended particles from water
    • Endoskeleton
      • Have fibers of spongin, a modified form of collagen
      • Typically have an endoskeleton also with spicules, small, needle-shaped structures with one to six rays
    • Reproduction
      • Reproduce asexually by budding
      • Reproduce sexually as egg and sperm are released into central cavity
        • Zygote develops into a flagellated larva that may swim to a new location
    19-
  • 16. Figure 19.6 Sponge anatomy 19-
  • 17. 19.7 Cnidarians have true tissues
    • Cnidarians (phylum Cnidaria) - an ancient group of invertebrates
      • Most in the sea, but a few freshwater species
    • Radially symmetrical and capture their prey with a ring of tentacles that have specialized stinging cells, cnidocytes
      • Each cnidocyte has a capsule called a nematocyst , containing a long, spirally coiled, hollow thread
    • Two basic body forms
      • Polyp - mouth is directed upward from the substrate
      • Medusa - mouth is directed downward
    • Cnidarians - a sac body plan with only one opening
    19-
  • 18. Figure 19.7A Cnidarian diversity 19-
  • 19. Figure 19.7B Anatomy of Hydra , a polyp 19-
  • 20. 19.8 Free-living flatworms have bilateral symmetry
    • Flatworms (phylum Platyhelminthes)
      • First phylum with bilateral symmetry
    • Have three germ layers
      • Ectoderm from which body wall develops
      • Endoderm from which digestive cavity develops
      • Mesoderm which contributes to organ formation
    • Have no coelum and are called acoelomates
    • Planarians have several body systems
      • Digestive System - pharynx leads to gastrovascular cavity
      • Excretory System - a series of interconnecting canals
      • Reproductive System - Hermaphrodites (both male and female sex organs) and perform cross-fertilization
      • Nervous System - brain and two lateral nerve cords are joined by cross-branches called transverse nerves
    19-
  • 21. Figure 19.8 Planarian anatomy 19-
  • 22. 19.9 Some flatworms are parasitic
    • Tapeworms
      • Endoparasites (internal parasites) of various vertebrates, including humans
        • Vary in length from a few millimeters to 20 meters
      • Tough body covering resistant to the host’s digestive juices
      • Scolex bears hooks and suckers for attachment to the intestinal wall of the host
    • Flukes
      • Endoparasites of various vertebrates
      • Anterior end of the animal has an oral sucker and at least one other sucker used for attachment to the host
      • Nearly 800,000 persons die each year from an infection called schistosomiasis
    19-
  • 23. Figure 19.9A Tapeworm ( Taenia solium ) anatomy and life cycle 19-
  • 24. Figure 19.9B Sexual portion of blood fluke ( Schistosoma spp.) life cycle 19-
  • 25. 19.10 Roundworms have a pseudocoelom and a complete digestive tract
    • Roundworms (phylum Nematoda) possess two anatomic features not previously seen
      • body cavity - pseudocoelom and is incompletely lined with mesoderm
      • complete digestive tract - it has both a mouth and an anus
    • Nonsegmented, meaning that they have a smooth outside body wall
    • Ascaris
      • Humans are infected with a roundworm called Ascaris when eggs enter the body via uncooked vegetables
    • Other Roundworm Parasites
      • Trichinosis - serious human infection acquired when humans eat meat that contains encysted larvae
      • Elephantiasis is caused by a roundworm called a filarial worm,
      • which utilizes mosquitoes as a secondary host
    19-
  • 26.
    • Figure 19.10A Ascaris Figure 19.10b Encysted Trichinella larva
    19-
  • 27. Figure 19.10C Elephantiasis 19-
  • 28. 19.11 A coelom gives complex animal groups certain advantages
    • Coelom - body cavity completely lined by mesoderm
    • Two groups
      • Protostomes - Molluscs, annelids, and arthropods
      • Deuterostomes - echinoderms and chordates
    • Two major events can be used to distinguish protostomes from deuterostomes
      • Blastopore - protostomes: mouth appears near blastopore; deuterostomes: anus appears near blastopore
      • Coelom formation - protostomes: splitting produces the coelom; deuterostomes: the coelom arises as a pair of mesodermal pouches from the gut wall
    • Advantages of a Coelom
      • Body movements are freer because outer wall can move independently of the enclosed organs
      • Ample space of a coelom allows complex organs and organ systems to develop
    19-
  • 29. Figure 19.11 Protostomes compared to deuterostomes 19-
  • 30. 19.12 Molluscs have a three-part body plan
    • All molluscs (phylum Mollusca) have a body composed of at least three distinct parts
      • The foot - strong, muscular portion used for locomotion
      • Visceral Mass - soft-bodied portion that contains internal organs
      • The mantle - covering that envelops the visceral mass
        • The mantle may secrete an exoskeleton called a shell
    • Gastropods (meaning stomach-footed) including snails and nudibranchs
      • Animal moves by muscle contractions that pass along its ventrally flattened foot
    • Cephalopods (meaning head-footed) including octopuses, squids, and nautiluses
      • The foot has evolved into tentacles about the head
    • Bivalves (shells have two part) including clams, oysters, scallops, and mussels
      • The clam is a filter feeder and food particles and water enter the mantle cavity by way of a siphon
    19-
  • 31. Figure 19.12A Body plan of a typical mollusc 19-
  • 32. Figure 19.12B Three groups of molluscs 19-
  • 33. 19.13 Annelids are the segmented worms
    • Annelids (phylum Annelida) are segmented, as can be seen externally by the rings that encircle the body
      • Partitions called septa divide the well-developed, fluid-filled coelom, which is used as a hydrostatic skeleton
      • Excretory system consists of nephridia, tubules that collect waste material and excrete it through an opening in the body wall
    • Oligochaetes
      • Earthworm is an oligochaete because it has few setae, bristles that anchor the worm
    • Polychaetes
      • Most annelids are polychaetes (having many setae per segment) that live in marine environments
    • Leeches
      • Have no setae, but have the same body plan as other annelids
      • Blood suckers that are able to keep blood flowing and prevent clotting
    19-
  • 34. Figure 19.13A Earthworm anatomy 19-
  • 35. Figure 19.13B Other annelids 19-
  • 36. 19.14 Arthropods have jointed appendages
    • Arthropods (phylum Arthropoda) are extremely diverse
      • More than one million species have been discovered
    • Six characteristics
      • Jointed appendages
      • Exoskeleton
      • Segmentation
      • Well-developed nervous system
      • Variety of respiratory organs
      • Reduced competition through metamorphosis
    19-
  • 37. Figure 19.14A Exoskeleton and jointed appendages of a crayfish, an arthropod 19-
  • 38. Figure 19.14B Monarch butterfly metamorphosis 19-
  • 39. 19.15 Well-known arthropods other than insects
    • Crustaceans - name derived from their hard, crusty exoskeleton
      • Largely marine arthropods that include crabs, barnacles, shrimps, and crayfish
      • Head usually bears a pair of compound eyes and five pairs of appendages
    • Arachnids include spiders, scorpions, ticks, mites, and harvestmen
      • Spiders have a narrow waist that separates the cephalothorax, with four pairs of legs, from the abdomen
    19-
  • 40. Figure 19.15A Crustacean diversity 19-
  • 41. Figure 19.15B Centipede and millipede 19-
  • 42. Figure 19.15C Spider and relatives 19-
  • 43. 19.16 Insects, the largest group of arthropods, are adapted to living on land
    • Insects - so numerous (>one million species) and diverse that the study of this one group is a major specialty in biology called entomology
    • Adapted to a life on land
      • Body is divided into head, thorax, and abdomen
      • Mouthparts adapted to each species’ way of life
      • Wings enhance an insect’s ability to survive
        • way of escaping enemies, finding food, facilitating mating, and dispersing offspring
    19-
  • 44. Figure 19.16 Insect diversity 19-
  • 45. 19.17 Echinoderms are radially symmetrical as adults
    • Echinoderms (phylum Echinodermata) lack chordate features, but are related to because they are deuterostomes
      • Radially, not bilaterally, symmetrical as adults
        • Their larva is a bilaterally symmetrical filter feeder
      • Adult echinoderms do not have a head, brain, or segmentation
        • Their nervous system consists of nerves in a ring around the mouth extending outward radially
    • Locomotion by a water vascular system that pumps water into many tube feet, expanding them
    • No complex respiratory, excretory, or circulatory system
      • Fluids within the coelomic cavity and the water vascular system carry out many of these functions
    • In ecosystems, most feed on organic matter in the sea or substratum
      • Sea stars prey upon crustaceans, molluscs, and other invertebrates
    19-
  • 46. Figure 19.17 Echinoderm structure and diversity 19-
  • 47. Further Innovations Allowed Vertebrates to Invade the Land Environment 19-
  • 48. 19.18 Four features characterize chordates
    • Dorsal supporting rod (notochord) extends the length of the body
    • Dorsal tubular nerve cord contains a canal filled with fluid
    • Pharyngeal pouches only during embryonic development in most vertebrates
    • A postanal tail extends beyond the anus
    19-
  • 49. Figure 19.18 The four chordate characteristics 19-
  • 50. 19.19 Invertebrate chordates have a notochord as adults
    • A few of the invertebrate chordates never replace the notochord with the vertebrae
      • Tunicates (subphylum Urochordata) live on the ocean floor as filter feeders
        • Larva is bilaterally symmetrical and has the four chordate characteristics
        • Metamorphosis produces the sessile adult
      • Lancelets (subphylum Cephalochordata) marine chordates only a few centimeters long
        • Lancelets retain the four chordate characteristics as adults
    19-
  • 51. Figure 19.19 The invertebrate chordates 19-
  • 52. 19.20 The evolutionary tree of vertebrates is based on five key features
    • Vertebrates
      • Fishes, amphibians, reptiles, birds, and mammals
      • Vertebrae are most obvious feature
      • Vertebral column is flexible because vertebrae are separated by disks, which cushion the vertebrae
        • The soft center of a disk presses on the spinal cord
      • Derived Characters Among Vertebrates
        • Jaws, Lungs, Jointed Limbs, and Amniotic Eggs
    19-
  • 53. Figure 19.20 Evolutionary tree of the chordates 19-
  • 54. 19.21 Jaws and lungs evolved among the fishes
    • Jawless Fishes (Class Agnatha)
      • Cylindrical and up to a meter long
      • Smooth, scaleless skin, no jaws or paired fins
    • Cartilaginous Fishes (Class Chondrichthyes) includes sharks, the rays, and the skates
      • Skeletons of cartilage, instead of bone
      • Shark senses
        • Able to sense electric currents in water
        • Lateral line system senses pressure waves caused by fish
        • Keen sense of smell
    • Bony Fishes (Class Osteichthyes) most numerous and diverse of all vertebrates
      • Ray-finned fishes - use their fins to balance and propel body
        • Have a swim bladder, which usually serves as a buoyancy organ
        • Bony scales that protect body but do not prevent water loss
    19-
  • 55. Figure 19.21A Evolution of jaws 19-
  • 56. Figure 19.21B Diversity of fishes 19-
  • 57. Figure 19.21C This transitional form links the lobes of the lobe-finned fishes to the limbs of ancestral amphibians 19-
  • 58. 19.22 Amphibians are tetrapods that can move on land
    • Amphibians (class Amphibia) means living on both land and in the water, represented by frogs, toads, newts, and salamanders
    • Characteristics
      • Adults have small lungs - air enters the mouth by way of nostrils
      • Respiration is supplemented by gas exchange through the smooth, moist, skin
    • Most members lead an amphibious life
      • Larval stage lives in water, and adult stage is on land
    19-
  • 59. Figure 19.22 Frogs and salamanders are well-known amphibians 19-
  • 60. 19.23 Reptiles have an amniotic egg and can reproduce on land
    • Reptiles (class Reptilia) diversified and most abundant between 245 and 66 MYA
    • The reptiles living today are mainly alligators, crocodiles, turtles, snakes, lizards, and tuataras
    • Body is covered with hard, keratinized scales, which protect animal from desiccation and from predators
    • Fertilization is internal, and the female lays leathery, flexible, shelled eggs
      • Amniotic egg made development on land possible and eliminated the need for a swimming larval stage
    • Fishes, amphibians, and reptiles are ectotherms
      • Body temperature matches the temperature of their environment
    19-
  • 61. Amniotic Egg 19-
  • 62. Figure 19.23 Reptilian diversity 19-
  • 63. 19.24 Birds have feathers and are endotherms
    • Birds (class Aves) are characterized by the presence of feathers
      • Lay a hard-shelled amniotic egg
        • Data suggests birds are related to bipedal dinosaurs and should be classified as such
      • Birds are adapted to fly
        • Forelimbs are modified as wings
        • Hollow, light bones
        • Horny beak has replaced jaws with teeth
      • Birds are endotherms and generate internal heat
        • May be associated with efficient nervous, respiratory, and circulatory systems
      • Seasonal migration of many species over very long distances
        • Navigate by day and night, whether it’s sunny or cloudy, by using the sun and stars and even the Earth’s magnetic field to guide them
    19-
  • 64. Figure 19.24A Bird flight 19-
  • 65. Figure 19.24B Types of bird beaks 19-
  • 66. 19.25 Mammals have hair and mammary glands
    • Mammals (class Mammalia) evolved during Mesozoic from reptiles called therapsids
    • Two chief characteristics
      • Hair: Mammals are endotherms, and hair aids temperature control
      • Milk-producing mammary glands: enable females to feed (nurse) their young without leaving them to find food
    19-
  • 67. Monotremes and Marsupials
    • Monotremes - mammals that have a cloaca , a terminal region of the digestive tract serving as a common chamber for feces, excretory wastes, and sex cells
      • Also lay hard-shelled amniotic eggs
    • Marsupials - begin their development inside the female’s body, but they are born in a very immature condition
      • Newborns crawl up into a pouch on their mother’s abdomen
    19-
  • 68. Figure 19.25A Monotremes and marsupials 19-
  • 69. Placental Mammals
    • Placental mammals - extraembryonic membranes of the reptilian egg are modified for internal development within the uterus of the female
      • Chorion contributes to the fetal portion of the placenta, while a part of the uterine wall contributes to the maternal portion
      • Nutrients, oxygen, and waste exchanged between fetal and maternal blood
    • Distinguished by their mode of locomotion
      • Bats have membranous wings supported by digits
      • Horses have long, hoofed legs; and whales have paddlelike forelimbs
    • Distinguished by the way of obtaining food
      • Mice have continuously growing incisors
      • Horses have large, grinding molars
      • Dogs have long canine teeth
    19-
  • 70. Figure 19.25B Placental mammals 19-
  • 71. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 19.26 Many vertebrates provide medical treatments for humans
    • Hundreds of pharmaceutical products come from vertebrates
      • Animals that produce poisons and toxins give us medicines that benefit us
      • Some produce proteins similar to human proteins to be used in medical treatment
    • Powerful applications of genetic engineering found in development of drugs and therapies for human diseases
      • Xenotransplantation, transplantation of vertebrate tissues and organs into human beings
      • Use of transgenic vertebrates for medical purposes does raise health and ethical concerns
    19-
  • 72. Figure 19.26 Vertebrates used for medical purposes 19-
  • 73. Connecting the Concepts: Chapter 19
    • As terrestrial mammals, humans might assume that terrestrial species are more successful than aquatic ones
      • If not for the myriad types of terrestrial insects, there would be more aquatic species than terrestrial ones on Earth
    • Adaptative radiation of mammals has taken place on land, and this might seem impressive to some
      • Actually, the number of mammalian species (4,800) is small compared to the molluscs (110,000 species)
    • Size and complexity of the brain is also sometimes cited as a criterion by which vertebrates are more successful than other living things
      • This characteristic has been linked to others that make an animal prone to extinction
      • Long life span, slow to mature, have few offspring, expend much energy caring for their offspring, and tend to become extinct if their normal way of life is destroyed
    19-

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