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Introduction to animals Introduction to Animals – Ch. 32 The Nature of Animals Section 32.1 Classification: ● 95-98% of animals are invertebrates ● Without a backbone ● 2-5% of animals are vertebrates ● With a backbone Animal Traits Characteristics: 1. 2. 3. 4. 5. 6. All animals are: Multicellular Eukaryotic Ingestive heterotrophs Lacking in cell walls Sexually reproductive Able to move 1. Multicellular Organization ● Cell specialization: the evolutionary adaptation of a cell for a particular function ● Tissue: group of similar cells that perform a common function ● Cell junctions: connections between cells that hold them together as a unit Atom Molecule or compound Levels of Organization Organ Tissue Organ system Organelle CELL Life begins Organism 2. Eukaryotic cells 3. Ingestive Heterotrophy ● Getting complex organic compounds (carbon) from sources other than the sun ● Ingestion: taking in food usually in the form of an other organism ● Digestion: the body’s process of extracting organic molecules from food Lions Feeding (Ingestion) 4. Lack of cell walls 5. Sexual Reproduction & Development ● Hermaphrodites: producing both eggs and sperm ● Examples: worms & sponges ● Most do NOT fertilize own eggs ● Why not? ● Zygote: diploid cell that results from the fusion of two haploid gametes ● Undergoes differentiation (cells becoming specialized to perform a specific function) Female Beetles Mating Courtship Young Male Mating and Mating Behaviors Leeches Exchange Sperm During Mating leech Mating Parthenogenesis: ● Females of some animals produce eggs, but the eggs develop without being fertilized! ● New offspring will be all female ● Example animals: some fishes, several kinds of insects, and a few species of frogs and lizards Parthenogenesis in the Komodo Dragon Video 6. Movement ● Sessile: attached & non-moving ● sponges ● Sedentary: move very little ● clam ● Motile: animals that can move ● humans ● Ability to move depends upon interaction between nervous tissue and muscle tissues ● Neurons: cells of nervous tissue SESSILE Sponge SEDENTARY Chiton MOTILE Cheetah Origin of Animals: ● Animals came about in the water ● Evolved from colonial protists: ● Each organism had its own function (for the colony) much like each cell of the animal body has its own function (for the organism) Vide o Body Structure: ● Symmetry is the arrangement of body parts around a central plane or axis ● Asymmetry occurs when the body can’t be divided into similar sections ● sponges Radial symmetry ● when body parts are arranged around a central point ● like spokes on a wheel ● echinoderms ● Most animals are sessile (attached) or sedentary (move very little) Bilateral symmetry ● when animals can be divided into equal halves along a single plane ● right and left sides that are mirror images of each other ● are usually motile ● Show cephalization ● concentration of sensory organs on the head (anterior) end What type of symmetry is this? Segmentation ● When an animal body is composed of a series of repeating similar units ● Example: earthworm (annelid) ● Segments may look different & have different functions ● Example: insects & crustaceans (arthropods) Anatomical Terms: Dorsal: back surface of animal Ventral: underside of animal Anterior: front end of animal Posterior: rear end of animal Lateral: sides of animal Medial: along midline of animal Proximal: near to Distal: away from Label the parts: Comparison of Invertebrates & Vertebrates Section 32.2 Invertebrate groups Video Invertebrates ● Simplest animals ● Contain the greatest number of different species ● Most are aquatic ● Do NOT have a backbone ● Includes: ● sponges, cnidarians, flatworms, roundworms, annelids, mollusks, arthropods, & echinoderms Sponges – Phylum Porifera Osculum of Sponge Sea Anemone – Phylum Cnidaria Tentacles of Sea Anemone More Phylum Cnidaria Brain Coral Red jellyfish * Flatworms – Phylum Platyhelminthes Marine Flatworm Planarian Roundworms - Phylum Nematoda Segmented Worms – Phylum Annelida Nematode Leech (segmented worm) Phylum Mollusca (With and Without Shells) snail nautilus scallop nudibranch octopus Phylum Arthropoda spider crayfish Horseshoe crab Dung beetle Phylum Echinodermata Sea fan (crinoid) starfish Brittle star Sand dollar Sea cucumber Symmetry ● Most are radial or bilateral ● Radial can receive stimuli and move in any direction (in water) Bilateral but NOT an invertebrate ● Some are highly cephalized Radia l Bilatera l Support of the Body ● Various types of support: 1. Simple skeletons (sponges) 2. Fluid-filled body cavity (roundworms) 3. Exoskeleton (crayfish) ● Rigid outer covering for protection of soft tissue 2 Types of Circulatory Systems: ● Open circulatory system: circulatory fluid is pumped by the heart through vessels into a body cavity ● Arthropods & most mollusks ● Closed circulatory system: circulatory fluid is restricted to vessels in a closed loop ● Squid (mollusk) VIDEO Digestive & Excretory Systems ● Gut: a digestive tract running through the body ● Liquid wastes are excreted as ammonia ● highly toxic Development ● ●Indirect Development: an intermediate larval stage occurs ● Flies ● Direct development: young animal appears similar to adult ● grasshoppers Indirect Developme nt Vertebrate Groups Video! Fishes – Classes Myxini, Cephalaspidomorphi, Chondrichthyes, Actinopterygii, and Sarcopterygii lancelet ray damselfish anglerfish salamander Class Amphibia toad frog newt Class Reptilia Turtle Snake Lizard Alligator Class Aves hummingbird ostrich lovebirds Class Mammalia Vertebrata ● More complex animals ● Most have a backbone made up of individual bones called vertebrae ● All species are in the Phylum Chordata ● From simplest to most complex groups: ● Fish ● Amphibians ● Reptiles ● Birds ● Mammals Support of Body ● Vertebrates have endoskeletons ● Internal skeletons ● Supports more weight ● Grows as animal grows (no molting) ● Some vertebrates have skeletons of cartilage ● sharks, rays, and skates ● Other vertebrates have skeletons of bone and cartilage ● reptiles, birds, & mammals Bone & Cartilage in Fetus Segmentation ● Vertebrae: repeating bony units of the backbone ● Vertebrae & ribs are segmented Body Covering ● Integument: outer covering of an animal ● Terrestrial animals are water-tight ● Why? ● Examples: feathers, hair, scales Respiration & Circulation ● Respiration (breathing): ● Aquatic = gills ● Terrestrial = lungs ● Circulation: ● Closed circulation with multi-chambered heart ● ● Separates oxygen and deoxygenated blood Improves efficiency Digestion & Excretion ● Digestion: ● Occurs in the gut (mouth → anus) ● Excretion: ● Kidneys: filters wastes from the blood while regulates water levels in the body Nervous System ● Highly organized brains ● Each part has its own function Section 32.3 Fertilization & Development Fertilization ● Definition: the union of the female and male reproductive gametes ● Results in a single diploid cell named the zygote I’m in! Fertilization Steps: VIDEO 1. 2. 3. 4. Sperm’s membrane fuses with egg’s membrane Electrical charge occurs to block entry of other sperm into egg Sperm nucleus merges with egg nucleus forming zygote DNA replication begins & cell division occurs Cleavage ● Definition: division of the zygote immediately following fertilization via mitosis ● Organism size does not increase even though number of cells does VIDEO Tissue Development ●Cleavage results in the formation of a hollow ball of cells called the blastula Blastula •The blastocoel is the center cavity of the blastula with 1 germ layer (blastoderm) Tissue Development ● The blastula invaginates ● folds inward at one point ● Called Gastrulation ● The opening is called the Archenteron blastopore ● The center is the primitive gut ● Archenteron blastopore Embryonic Development VIDEO Tissues Tissue Development: ● Germ layers: tissues found in the embryos of all animals except sponges ● Typically three layers in depth ● All body features arise from one of these layers ● Body cavities: fluid-filled space that forms between the digestive tract & outer wall of body during development ● Aids in movement of animal ● Reservoir for transport of materials Germ Layers ● Form tissues, organs, & systems ● NOT present in sponges ● Ectoderm (outer) – forms skin, nerves, sense organs ● Endoderm (inner) – forms liver and lungs ● Mesoderm (middle) – forms muscles & other systems Animation Body Cavities Coelom = Body Cavity ●Internal body cavity fully lined with mesoderm ● Body organs suspended in this cavity Types of body cavities: 1. Acoelomates: no body cavity ● ● solid bodies filled with cells sponges, cnidarians, & flatworms 2. Pseudocoelomates: “false body cavity” ● ● have a functional body cavity NOT fully lined with mesoderm Rotifer, roundworms 3. Coelomates: true coelom ● Mollusks, annelids, arthropods, chordates Acoelomate ● no body cavity ● ● solid bodies filled with cells sponges, cnidarians, & flatworms Pseudocoelomate ● “false body cavity” ● have a functional body cavity NOT fully lined with mesoderm Rotifer, roundworms ● Coelmate: ● true coelom ● Mollusks, annelids, arthropods, chordates