Transcript Animals
Animals AP Biology Mrs. Ramon Intro. To Animal Evolution What is an animal? Multicellular, heterotrophic eukaryotes Lack cell walls Two unique types of tissues: nervous tissue for impulse conduction and muscle tissue for movement. Most animals reproduce sexually, with the diploid stage usually dominating the life cycle Animal Evolution Cnidaria Porifera sponges jellyfish Nematoda Platyhelminthes Annelida Mollusca Echinodermata Arthropoda flatworms roundworms mollusks segmented worms redundancy, segmentation specialization, mobility insects spiders starfish Chordata vertebrates body & brain backbone size, mobility body size endoskeleton coelom digestive sys radial body cavity body complexity digestive & repro sys bilateral symmetry tissues multicellularity Ancestral Protist distinct body plan; cephalization specialized structure & function, muscle & nerve tissue specialization & body complexity bilateral Early Embryonic Development From Protozoans to Animals Body Cavity Space for organ system development increase digestive & reproductive systems increase food capacity & digestion increase gamete production Coelem mesoderm & endoderm interact during development allows complex structures to develop in digestive system ex. stomach acoelomate ectoderm mesoderm endoderm pseudocoelomate ectoderm mesoderm endoderm pseudocoel coelomate ectoderm mesoderm coelom cavity endoderm protostome vs. deuterostome Body Cavities (cont.) Acoelomates (the phylum Platyhelminthes) have a solid body and lack a body cavity. Body Cavities (cont.) In some organisms, there is a body cavity, but it is not completely lined by mesoderm. This is termed a pseudocoelom. These pseudocoelomates include the rotifers (phylum Rotifera) and the roundworms (phylum Nematoda). Body Cavities (cont.) Coelomates are organisms with a true coelom, a fluid-filled body cavity completely lined by mesoderm. Invertebrates: Porifera Sponges Adults sessile No distinct tissues or organs No symmetry Invertebrates: Cnidaria Hydras, jellies, sea anemones and corals Tissues, but no organs Two cell layers Gastrovascular cavity Sessile (anemone) or floating (jelly) Cnidocytes (tentacles) Invertebrates: Platyhelminthes Flatworms Tapeworm, planaria Mostly parasitic Bilateral symmetry Cephalization Acoelomates with gastrovascular cavities Asexual or sexual reproduction Invertebrates: Nematoda Roundworms Bilateral symmetry Nonsegmented pseudocoelomates covered with tough cuticles Digestive system Many are parasitic: Hook worm Trichinella spiralis causes trichinosis Undercooked meat Invertebrates: Mollusca Snails, slugs, clams squid Bilateral symmetry (some exceptions) True coelem Polyplacophora (chitons) Gastropoda (snails and slugs), Bivalvia (clams, oysters, and other bivalves) Cephalopoda (squids, octopuses and nautiluses). Invertebrates: Annelida Segmented worms Earthworms, leeches Segments Increase mobility Redundancy in body sections Bilateral symmetry True coelem Invertebrates: Arthropoda Spiders, insects, crustaceans A billion billion (1018) individuals (2/3 organisms) Bilateral symmetry Body segmentation Hard exoskeleton Chitin and protein Jointed appendages Arthropod Classes: Insecta 26 different orders within the Class Insecta Defining features: 6 legs 3 body parts Arthropod Classes: Crustacea Lobsters, crab, crayfish, shrimp and barnacles Defining features: Gills 2 pairs of antennae Invertebrates: Echinodermata Sea stars, brittle stars, sea urchins, sand dollars and sea cucumbers Sessile or slow moving Water vascular system Locomotion, feeding and gas exchange Spiny endoskeleton Radial symmetry Vertebrates: Chordata Fish, amphibians, reptiles, birds and mammals Features: Notochord Disks Nerve chord Brain and spinal chord Pharyngeal slits Muscular postanal tail Vertebrates: Fish 450 mya Characteristics bony & cartilaginous skeleton jaws & paired appendages (fins) scales body function gills body structure salmon, trout gills for gas exchange two-chambered heart; single loop blood circulation ectotherms reproduction external fertilization external development in aquatic egg body Transition to Land Evolution of tetrapods Humerus Femur Pelvis Tibia Ulna Shoulder Radius Lobe-finned fish Fibula Pelvis Femur Humerus Tibia Fibula Early amphibian Ulna Shoulder Radius Vertebrates: Amphibian 350 mya Characteristics legs (tetrapods) moist skin buccal cavity glottis closed body function lung body structure frogs salamanders toads lungs (positive pressure) & diffusion through skin for gas exchange three-chambered heart; veins from lungs back to heart ectotherms reproduction external fertilization external development in aquatic egg metamorphosis (tadpole to adult) Vertebrates: Reptiles 250 mya Characteristics body structure dry skin, scales, armor body function dinosaurs, turtles lizards, snakes alligators, crocodile lungs for gas exchange thoracic breathing; negative pressure three-chambered heart ectotherms leathery reproduction shell embryo amnion internal fertilization external development in amniotic egg chorion allantois yolk sac Vertebrates: Birds (Aves) 150 mya finches, hawk ostrich, turkey Characteristics body structure body function feathers & wings thin, hollow bone; flight skeleton very efficient lungs & air sacs four-chambered heart endotherms reproduction internal fertilization external development in amniotic egg trachea lung anterior air sacs posterior air sacs Vertebrates: Mammals 220 mya / 65 mya Characteristics body structure hair specialized teeth body function mice, ferret elephants, bats whales, humans muscles contract lungs, diaphragm; negative pressure four-chambered heart endotherms reproduction internal fertilization internal development in uterus nourishment through placenta birth live young mammary glands make milk diaphragm contracts Vertebrates: Mammals Sub-groups monotremes egg-laying mammals lack placenta & true nipples duckbilled platypus, echidna marsupials pouched mammals offspring feed from nipples in pouch short-lived placenta koala, kangaroo, opossum placental true placenta nutrient & waste filter shrews, bats, whales, humans