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    19 Lecture Ppt 19 Lecture Ppt Presentation Transcript

    • Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 19 Evolution of Animals
    • Key Innovations Distinguish Invertebrate Groups 19-
    • 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-
    • Figure 19.1 Developmental stages of a frog 19-
    • 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-
    • Figure 19.2 The colonial flagellate hypothesis 19-
    • Radial and Bilateral Symmetry 19-
    • 19.3 The traditional evolutionary tree of animals is based on seven key innovations (figure 19.3A) 19-
    • Animal Body Cavities
      • Figure 19.3B Types of body cavity
      19-
    • 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-
    • Figure 19.4A Proposed new evolutionary tree 19-
    • Figure 19.4B Roundworms and arthropods are molting animals 19-
    • 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-
    • 19-
    • 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-
    • Figure 19.6 Sponge anatomy 19-
    • 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-
    • Figure 19.7A Cnidarian diversity 19-
    • Figure 19.7B Anatomy of Hydra , a polyp 19-
    • 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-
    • Figure 19.8 Planarian anatomy 19-
    • 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-
    • Figure 19.9A Tapeworm ( Taenia solium ) anatomy and life cycle 19-
    • Figure 19.9B Sexual portion of blood fluke ( Schistosoma spp.) life cycle 19-
    • 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-
      • Figure 19.10A Ascaris Figure 19.10b Encysted Trichinella larva
      19-
    • Figure 19.10C Elephantiasis 19-
    • 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-
    • Figure 19.11 Protostomes compared to deuterostomes 19-
    • 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-
    • Figure 19.12A Body plan of a typical mollusc 19-
    • Figure 19.12B Three groups of molluscs 19-
    • 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-
    • Figure 19.13A Earthworm anatomy 19-
    • Figure 19.13B Other annelids 19-
    • 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-
    • Figure 19.14A Exoskeleton and jointed appendages of a crayfish, an arthropod 19-
    • Figure 19.14B Monarch butterfly metamorphosis 19-
    • 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-
    • Figure 19.15A Crustacean diversity 19-
    • Figure 19.15B Centipede and millipede 19-
    • Figure 19.15C Spider and relatives 19-
    • 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-
    • Figure 19.16 Insect diversity 19-
    • 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-
    • Figure 19.17 Echinoderm structure and diversity 19-
    • Further Innovations Allowed Vertebrates to Invade the Land Environment 19-
    • 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-
    • Figure 19.18 The four chordate characteristics 19-
    • 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-
    • Figure 19.19 The invertebrate chordates 19-
    • 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-
    • Figure 19.20 Evolutionary tree of the chordates 19-
    • 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-
    • Figure 19.21A Evolution of jaws 19-
    • Figure 19.21B Diversity of fishes 19-
    • Figure 19.21C This transitional form links the lobes of the lobe-finned fishes to the limbs of ancestral amphibians 19-
    • 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-
    • Figure 19.22 Frogs and salamanders are well-known amphibians 19-
    • 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-
    • Amniotic Egg 19-
    • Figure 19.23 Reptilian diversity 19-
    • 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-
    • Figure 19.24A Bird flight 19-
    • Figure 19.24B Types of bird beaks 19-
    • 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-
    • 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-
    • Figure 19.25A Monotremes and marsupials 19-
    • 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-
    • Figure 19.25B Placental mammals 19-
    • 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-
    • Figure 19.26 Vertebrates used for medical purposes 19-
    • 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-