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Animal Diversity (1 &) 2 Multicellular, eukaryotic, heterotrophic organisms that feed by INGESTION
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Body symmetry Radial symmetryBilateral symmetry
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Anterior Ventral Dorsal Posterior
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Tissue organization 2 tissue layers = Radially symmetric 3 tissue layers = Bilaterally symmetric
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Two tissue layers: Endoderm and Ectoderm
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Ectoderm Endoderm Gut Ectoderm Endoderm Gut Ex: Hydra
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Three tissue layers: Ectoderm, Mesoderm, Endoderm
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Ectoderm: External Layer Skin cells of epidermis Neurons of brain Mesoderm: Middle Layer Cardiac muscle, Skeletal muscle,Kidney cells, Red blood cells, Smooth muscle in gut Endoderm: Internal Layer Lung (Alveolar) cells Thyroid cells Pancreatic cells
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Body cavity Acoelomate Pseudocoelomate Eucoelomate
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Other characteristics: Openings into digestive tract: One opening or tube within a tube? Open vs. closed circulatory system Organs for gas exchange Organs for excretion Endoskeleton, exoskeleton, hydrostatic skeleton? Segmentation
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Porifera (i.e. sponges)
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Cnidaria (e.g. Hydra, sea anemones, jellyfish) 2 tissue layers
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Platyhelminthes (Flatworms) 3 tissue layers Acoelomate unsegmented No internal organs = must be flat to allow O2 and nutrients in via diffusion Most are parasitic – Schistosomiasis is a disease caused by these guys. Tapeworm too.
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Annelida (Clamworms and earthworms) Segmentation! Organs! They’re hydrostatic!
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Annelida (Clamworms and earthworms)
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Mollusca More than 85,000 species!
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Characteristics of most molluscs: Hard external shell for protection Mantle (excretes shell) Visceral mass Muscular foot for locomotion Snail radula!
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Ex: cuttlefish
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Adductor muscles are well- developed in scallops because they’re active swimmers. (They’re also tasty) Basic bivalve anatomy
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Onwards! …to Ecdysozoa = molting animals (Nematoda and Arthropoda) Body covering = cuticle = exoskeleton
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Nematoda Most abundant animal on Earth Pseudocoelomate Up to a million different species (only like 50k described) 15,000 species are described as parasitic Sheds proteinaceous cuticle LOTS of investment in reproductive organs
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Arthropoda Animals with exoskeleton, segmented body, and jointed appendages Exoskeleton is periodically shed Four subphyla: Cheliceriformes, Myriapoda, Crustacea, Hexapoda Exoskeleton is mainly chitin First organisms to fly – unoccupied niche (air) allowed for massive radiation
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Cheliceriformes No antennae, no jaws Pincer-like appendages called chelicera used for grasping and fragmenting food
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Myriapoda Millipedes 2 pairs of legs per segment Detritivores Centipedes 1 pair of legs per segment Predators
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Crustacea Biramous (two-parted) limbs (even barnacles) Most are free-living aquatic animals Some (e.g. pill bugs) are terrestrial Some (e.g. barnacles) are sessile Ex: Crustacean claws branch into 2 segments
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Hexapoda: Six-legged arthropods
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External insect anatomy 3 distinct body units: head, thorax, and abdomen
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Insect head: Search for: compound eyes, ocelli, antennae, labrum, mouthparts
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Insect mouthparts: Mandible, maxilla, labium Chewing mouthparts (e.g. grasshopper) Evolution of mouthpart morphology A: Chewing B: Lapping (e.g. bee) C: Siphoning (e.g. moth) D: Sucking (e.g. mosquito)
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Arthropod respiration: Tracheal system
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No labs next week. Then only two more labs: - Animal Diversity 3 (chordates and starfish) - and then a final lab practical (no lecture for the last lab) I will post a study guide this week on thinkbiologically.com Don’t forget to turn in your reports! Lots to do today! Have fun! Final notes:
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