Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Animal Evolution – The Invertebrates
Document related concepts
Organisms at high altitude wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Living things in culture wikipedia , lookup
Developmental biology wikipedia , lookup
Aquatic ape hypothesis wikipedia , lookup
Regeneration in humans wikipedia , lookup
Evolutionary history of life wikipedia , lookup
Transcript
Animal Groups Animal Evolution – The Invertebrates Chapter 23 Comparing Key Groups Body Symmetry: Radial and Bilateral Most animals are bilateral Evolutionary trends toward • Greater size • Compartmentalization (division of labor among cells, tissues, and organs) • Integration of specialized activities that keep the organism alive 1 Body Organization Body Cavities Cephalization Most bilateral animals have a coelom and a complete gut • Sensory cells concentrated at the head Segmentation • Repetition of body units, front-to-back Key Concepts: INTRODUCING THE ANIMALS placozoans sponges cnidarians flatworms rotifers mollusks annelids roundworms arthropods echinoderms chordates protostomes, mouth forms first in embryos radial ancestry, two germ layers no true tissues deuterostomes, anus forms first in embryos bilateral ancestry, three germ layers true tissues Animals • Multicelled heterotrophs (ingest other organisms) • Grow and develop through a series of stages • Actively move about during all or part of life cycle multicelled body fungi choanoflagellates Cells of most animals form tissues and extracellular matrixes Fig. 23.6, p.364 2 23.3 Sponges (Phylum Porifera) Sponges Sponges • No symmetry, tissues, or organs • Flattened cells line the body wall (many pores; spikes of silica and/or proteins) • Filter feeders (flagellated collar cells absorb food; amoeboid cells digest and distribute it) • Hermaphrodites • Zygote develops into free-living larva 23.4 Cnidarians (Phylum Cnidaria) Cnidarian Body Plans Jellyfishes, corals, and sea anemones • Radial, tentacled carnivores • Gastrovascular cavity (respiration and digestion) • True epithelial tissues with a jellylike matrix in between • Simple nervous system (nerve net) • Hydrostatic skeleton 3 Unique Cnidarian Weapons Cnidarian Predators Nematocysts • Used to capture prey and for defense Cnidarian Life Cycles 23.5 Flatworms (Phylum Platyhelminthes) Free-living turbellarians (planarians), parasitic tapeworms and flukes • Simplest animals with organ systems • Paired nerve cords, ganglia • Hermaphrodites 4 Parasite Life Cycle: Blood Fluke Parasite Life Cycle: Tapeworm 23.6 Annelids Segmented worms (earthworms, polychaetes) and leeches • Closed circulatory system • Digestive and excretory systems, soluteregulating nephridia • Nervous system, ganglia in each segment • Muscles and fluid in chambers act as a hydrostatic skeleton • Hermaphrodites head end secretory organ Fig. 23.18, p.371 5 Polychaete 23.7 Mollusks (Phylum Mollusca) Including gastropods (snails), bivalves (scallops), chitons, nudibranchs, cephalopods • 100,000 named species Aquatic Snail Body Plan Cephalopods The fastest (squids), largest (giant squids), and smartest (octopuses) invertebrates Have a mantle • Sheetlike part of the body mass, draped back on itself 6 Cephalopods Cuttlefish Body Plan 23.8 Roundworms (Phylum Nematoda) Parasitic Roundworms More than 22,000 kinds of roundworms • • • • • • Free-living decomposers or parasites Some agricultural pests and human parasites Cylindrical body with bilateral features A cuticle that is molted A complete gut Organ systems in a false coelom 7 Key Concepts: BILATERAL INVERTEBRATES Simple Arthropods Trilobite, millipede, centipede Most animals show bilateral symmetry Bilateral animals have tissues, organs, and organ systems All adult tissues arise from two or three simple layers that form in early embryos Arthropod Characteristics 23.10 Chelicerates Key arthropod adaptations Horseshoe crabs and arachnids (spiders, scorpions, ticks, and mites) • • • • Hardened exoskeleton Jointed appendages Specialized and fused segments (wings) Efficient respiratory and sensory structures (eyes, antennae) • Predators, parasites, or scavengers 8 23.11 Crustaceans Insect Diversity Mostly marine crustaceans (crabs, lobsters, barnacles, krill, and copepods) 23.13 Unwelcome Arthropods 23.14 Echinoderms Spiders, ticks, and mosquitoes Sea stars, sea urchins, sea cucumbers, etc. • Exoskeleton with spines, spicules, or plates of calcium carbonate • Water-vascular system with tube feet • Adults are radial, but bilateral traits appear in larval stages 9 Echinoderms: “Spiny-Skinned” Fig. 23.34, p.381 24.1 Chordate Heritage Four features define chordates Animal Evolution – The Vertebrates Chapter 24 • • • • A notochord A dorsal hollow nerve cord A pharynx with gill slits A tail extending past the anus All features form in embryos • May or may not persist in adults 10 Chordate Family Tree Invertebrate Chordates Tunicates and lancelets (marine filter-feeders) Lancelet Body Plan Craniates Chordates with a braincase of cartilage or bone • Hagfish (jawless fish): Simplest modern craniate 11 24.2 Vertebrate Evolution Major Vertebrate Groups Key innovations laid the foundation for adaptive radiations of vertebrates • Vertebral column of cartilaginous or bony segments • Jaws evolved in predatory fishes • Gills evolved in water, then lungs for dry land • Paired fins were a starting point for other limbs Gill-Supporting Structures Key Concepts: TRENDS AMONG VERTEBRATES 24.3 Jawed Fishes and Tetrapods In some vertebrate lineages, a backbone replaced the notochord as the partner of muscles used in motion Jawed fishes Jaws evolved, sparking the evolution of novel sensory organs and brain expansions On land, lungs replaced gills, and more efficient blood circulation enhanced gas exchange Fleshy fins with skeletal supports evolved into limbs, now typical of vertebrates on land • Cartilaginous fishes (sharks and rays) • Bony fishes Body plans adapted to life in water • Streamlined shape reduces drag • Swim bladder (in bony fishes) adjusts buoyancy 12 Cartilaginous Fishes Bony Fishes The most diverse vertebrates • Lungfishes • Lobe-finned fishes (coelacanth) • Ray-finned fishes Early Lineages 24.4 Amphibians Coelacanth, lungfish, and Devonian tetrapod Frogs, toads, and salamanders • Carnivorous vertebrates • Adapted to life on land (lungs, 3-chambered heart) • Nearly all return to the water to reproduce 13 Amphibian Evolution 24.5 Vanishing Amphibians Many amphibians now face extinction due to pollution and habitat loss 24.6 Amniotes 24.7 Dinosaur Extinctions K-T asteroid impact hypothesis First vertebrates able to complete their life cycle on dry land • A huge asteroid impact caused extinction of last dinosaurs; spared earliest birds and mammals • Water-conserving skin and kidneys • Amniote eggs (four membranes) • Active life-styles 14 24.8 Modern Reptiles Major Groups • • • • • Turtles (shell attached to skeleton) Lizards (the most diverse reptiles) Snakes (limbless) Tuataras (some amphibian-like traits; third eye) Crocodilians (closest relatives of birds) Fig. 24.17, p.397 Fig. 24.17, p.397 Fig. 24.17, p.397 15 Reptile Characteristics hindbrain, midbrain, forebrain General characteristics • Live on land or in water • Cold-blooded • Have a cloaca (opening for wastes and reproduction) • Eggs are fertilized in the body, usually laid on land olfactory lobe (sense of smell) spinal vertebral cord column gonad kidney (control of water, solute levels in internal environment) snout unmatched rows of teeth on upper and lower jaws esophagus lung heart liver stomach intestine cloaca Fig. 24.16, p.396 24.9 Birds Bird Eggs Birds are the only modern animals with feathers Birds are warm-blooded amniotes 16 Adaptations for Flight and Migration 24.10 Mammals Feathers, lightweight bones, and highly efficient respiratory and circulatory systems Animals with hair, females that nourish young with milk from mammary glands, a single lower jawbone and four kinds of teeth Modern Mammals Three Major Lineages Three major lineages • Egg-laying mammals (monotremes) • Pouched mammals (marsupials) • Placental mammals (eutherians), the most diverse and widespread mammals 17 Placental Mammals Primates Primate Evolution The Foramen Magnum Four-legged walkers versus upright walkers Key trends • • • • • • Better daytime vision Upright walking (bipedalism) More refined hand movements Smaller teeth Bigger brains Social complexity (extended parental care; culture evolved in some lineages) 18 24.12 Emergence of Early Humans Australopiths: Upright Walking Hominoids and hominids originated in Africa Early Humans 24.13 Emergence of Modern Humans Humans (Homo) arose 2 million years ago Extinct Neandertals and modern humans are close relatives with distinct gene pools • H. habilis was an early toolmaking species • H. erectus dispersed into Europe and Asia Modern H. sapiens evolved 195,000 years ago 19 Dispersal of Homo sapiens Based on fossils and studies of genetic markers 20
