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Biology 120 Lab Cerritos College The Animal Kingdom Part I – The Lower Invertebrates (rev. 08.17.03) I. INTRODUCTION TO THE KINGDOM ANIMALIA All animals are multicellular, eukaryotic heterotrophs. A. SYMMETRY: Think "balance" – plane(s) by which an organism can be divided to give similar pieces. RADIAL - _________________________________________________________________________ BILATERAL - ______________________________________________________________________ ASYMMETRY - ____________________________________________________________________ B. REPRODUCTION: The ability to "create" one's own kind. SEXUAL - _________________________________________________________________________ MONOECIOUS - _______________________________________________________________ DIOECIOUS - __________________________________________________________________ ASEXUAL - ________________________________________________________________________ II. THE LOWER INVERTEBRATES A. THE PHYLUM PORIFERA THE SPONGES Cellular level of organization. All are aquatic, most are marine. Most are asymmetrical (few have radial symmetry). Reproduction is sexual, but asexual reproduction possible for some. B. THE PHYLUM CNIDARIA [formerly known as COELENTERATA; refers to a sac-like body cavity] All are aquatic, most are marine. Body consists of two tissues “glued together”. They have no “real” organs. All have radial symmetry and have either of two (2) body forms: POLYP – long body with tentacles MEDUSA – short, bell-shaped body, with tentacles Examples: jellies, hydra, sea anemones, and corals. There is sexual and asexual reproduction stages in the “life cycle” of some. Medusae and Polyps in the “life cycle” of some. Toxicity of their venom varies. 1. SINGULAR CNIDARIANS: EXAMPLE – HYDRA [fresh water], JELLIES [marine], ANEMONES [marine] EPIDERMIS - _________________________________________________________________________ GASTRODERMIS - ____________________________________________________________________ MESOGLIAL - ________________________________________________________________________ CNIDOBLAST - _______________________________________________________________________ TENTACLE - _________________________________________________________________________ 2. COLONIAL CNIDARIANS: EXAMPLES – OBELIA & CORALS [marine] REPRODUCTIVE POLYP - ______________________________________________________________ SEXUAL MEDUSAE - __________________________________________________________________ FEEDING POLYP - ____________________________________________________________________ EXOSKELETON - _____________________________________________________________________ C. THE PHYLUM PLATYHELMINTHES (Flatworms [platy = flat / helminthes = worms]) These worms are dorsoventrally flattened with Bilateral Symmetry. They are Acoelomic (lack a body cavity) – They have a third tissue layer and also have an organ system level of organization MESODERM (MID-LAYER TISSUE) - ___________________________________________________ CEPHALIZATION - __________________________________________________________________ TRUE ORGANS - ___________________________________________________________________ But, NO RESPIRATORY & CIRCULATORY SYSTEMS (gas exchanges by diffusions alone) 3 "CLASSES" WITHIN THE PHYLUM PLATYHELMINTHES 1. FLATWORMS (Turbellaria) – FREE LIVING WORMS Reproduction is either asexual or sexual: 1. Asexual – transverse division and then regeneration (via mitosis) of "parts". 2. Sexual – monoecious with cross-fertilization. EXAMPLE – PLANARIA WORMS (View live animals and model) EYESPOTS – __________________________________________________________________ TOUCH AND CHEMORECEPTORS – ______________________________________________ PROBOSCIS – _________________________________________________________________ INCOMPLETE DIGESTIVE SYSTEM – _____________________________________________ 2. TAPEWORMS (Trematoda) 2 Intestinal parasites in host animal. No digestive system; no adult locomotion. Lots of fertilized eggs produced. Monoecious – with self-fertilization SCOLEX - _____________________________________________________________________ PROGLOTTIDS - _______________________________________________________________ CUTICLE - ____________________________________________________________________ 3. FLUKES (Cestoda) Parasitic on variety of host organs. Liver, brain, kidneys, blood, ... First host is an invertebrate and final host is a vertebrate. D. THE PHYLUM NEMATODA (Roundworms; name refers to a “thread-like” body) Bilateral symmetry. All are Dioecious. Lifestyles: Some are free-living, but others are parasitic. ADVANCEMENTS: PSEUDOCOELOM -____________________________________________________________ COMPLETE DIGESTIVE SYSTEM - _______________________________________________ SEXUAL DIMORPHISM - ________________________________________________________ Females: larger than male (but size is relative term!) Males: smaller than female & have a "Spicule" (useful distinction!) - _________________ _______________________________________________________________________ SOME MALADIES CAUSED BY PARASITIC ROUNDWORMS ELEPHANTIASIS (FILARIAL WORM) - ______________________________________________ TRICHINOSIS (TRICHONELLA) - _________________________________________________ "HOOKWORMS" "PINWORMS" "WORMS" YOUR PET GETS ADDITIONAL VOCABULARY: FREE-LIVING - _____________________________________________________________________________ PARASITIC - ______________________________________________________________________________ SELF-FERTILIZATION - _____________________________________________________________________ CROSS-FERTILIZATION - ___________________________________________________________________ REGENERATION - __________________________________________________________________________ 3