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Kingdom Animalia Characteristics 1. 2. 3. 4. 5. 6. Heterotrophic (ingest their food) Eukaryotic Multicellular (made of many cells) Movement Sexual reproduction Absence of a cell wall 7. Blastula (hollow ball of cells) formation (except in sponges) Gives rise to three tissues 3 tissue layers Ectoderm Outer skin, nervous, sensory Endoderm Digestive and respiratory structures Mesoderm Skeleton, muscles, circulatory, reproductive 8. Tissues (all animals except sponges) Body Symmetry • Asymmetrical: irregular in shape; sponge Radial symmetry: body parts arranged around a central axis • Coral, jellyfish Bilateral symmetry: distinct left and right halves • Butterfly Most have anterior concentration of sensory structures (cephalization) Internal Body Cavity A. Acoelomate: No body cavity. Example: flatworm B. Pseudocoelomate: body cavity between mesoderm and endoderm • Example: roundworm C. Coelomate: fluid filled space between body wall and digestive tract, protects organs during movement • Example: earthworm, human Animal Body Systems A. Digestion: • Sponges digest intracellularly while all other animals digest extracellularly • Hydra has a gut with one opening, while more advanced animals have 2 B. Respiration • Simple animals (sponges) use diffusion • Some aquatic and terrestrial animals use gills (must stay moist) • Other organs, such as lungs, have evolved Which are more efficient: gills or lungs? C. Circulation • Simple animals use diffusion • Two types of circulatory systems are: 1. Open circulatory system: fluid leaves the circulatory vessels. Example: clam 2. Closed circulatory system: blood remains in the circulatory vessels. Example: earthworm D. Conduction of Nerve Impulses • Nerve cells (neurons) are specialized for carrying electrical impulses • Found in all animals except sponges • Simplest arrangement is a nerve net (hydra) • A nerve cord and brain with sensory structures such as eyes are more advanced E. Support • The skeleton supports the body and allows for movement • Muscles contract against the framework of the skeleton 1. Hydrostatic skeleton – fluid under pressure in a closed cavity • Seen in soft-bodied invertebrates such as the hydra and jellyfish Worms have hydrostatic skeleton 2. Exoskeleton – rigid, external skeleton found in arthropods, bivalves • Muscles are attached to inside of skeleton, which protects organs 3. Endoskeleton – embedded inside an animal, such as the bones within a mammal F. Excretion – removal of wastes produce by cellular metabolism • One toxic waste is ammonia • Some animals excrete waste through skin or gills • Others use kidneys or other structures designed to minimize water loss Reproductive Strategies 1. Asexual Reproduction – does not involve the fusion of 2 gametes 2. Sexual reproduction • Some animals, called hermaphrodites, have both testes and ovaries. Examples: slugs, earthworms, some fish • External fertilization: aquatic animals release sperm and eggs near each other • Internal fertilization: union of sperm and egg occurs within the female’s body Invertebrates: more than 95% of all animal species Phylogenetic tree Porifera Cnidaria Platyhelminthes Annelida Mollusca Echinodermata Nematoda Arthropoda Chordata RADIAL DUETEROSTOMES PROTOSTOMES NO TISSUES I. Phylum Porifera Sponges Sponges • • • • asymmetrical filter-feeders, feed intracellularly sessile (live attached to an object) Reproduce asexually or sexually (can have separate sexes or be hermaphrodites) II. Phylum Cnidaria • Jellyfish, hydra, Portuguese man-of-war, coral, sea anemone Evolutionary milestone is: • Tissues • Extracellular digestion in a gastrovascular cavity • Tentacles with stinging cells • Two body forms are medusa and polyp Examples Moon jellyfish Is this a polyp or medusa? Hydra Portuguese man-of-war Close up view of tentacles Coral A hydra feeding Box jellyfish – can be very deadly III. Phylum Platyhelminthes • Evolutionary milestone is bilateral symmetry A. Commonly known as flatworms B. Examples include free-living planarian and parasitic tapeworms C. Oxygen, carbon dioxide, digested food all move by diffusion Most have anterior concentration of sensory structures (cephalization) D. Tapeworm (parasitic) can be avoided by properly cooking food Planarian is free-living IV. Phylum Nematoda • Roundworms • Evolutionary milestone is body cavity (pseudocoelom) • Examples include: • Heartworms in dogs and cats • Hookworms • Free living roundworms Characteristics include a one-way digestive tract (2 openings) Hookworms are acquired by walking barefoot in contaminated soil V. Phylum Mollusca Mollusk Body Plan 60 Types of Mollusks 61 62 63 Cephalopods -Many have an ink sac and are capable of expelling ink to confuse predators -Octopuses and squids can change color using pouches of pigment called chromatophores 64 VI. Phylum Annelida • Segmented worms brain blood vessels hearts muscle mouth digestive tract segment nerve cord Characteristics • Cerebral ganglion, or primitive brain in an anterior segment • Coelom, or true body cavity • Closed circulatory system • excretory structures called nephridia • Earthworms are hermaphroditic -Clitellum secretes mucus that holds the worms together during mating -Also secretes a mucus cocoon, in which the fertilized egg develops 67 Marine worms 68 Types A. Marine worms; largest group • may burrow, or live in protective tubes B. Earthworms Describe the two useful functions earthworms provide as they eat soil. 1. Aerate the soil, allowing air and water to penetrate 2. Their castings (wastes) act as fertilizer C. Leeches • have suckers at both ends of body • most are predators or scavengers, but some are parasites VII. Phylum Arthropoda • Evolutionary Milestone is Jointed appendages VIII. Echinodermata VIII. Phylum Echinodermata A sea star, regenerating 2 arms. This will take over a year! Sand dollars Sea Urchins Evolutionary milestone is deuterostome embryo development Characteristics of Echinoderms A. Live in marine environments B. Have an endoskeleton, covered by a thin epidermis. C. Radial Symmetry (bilateral as larvae)