Chapter 33 Wednesday April 6 2016 1 42 PM Chapter 33 Introduction to Invertebrates Introduction to Invertebrates o o o 95 of all animal species 35 phyla Most are aquatic freshwater or marine Big exception arthropods have many land species Animal form follows function o Focus on adaptations for lifestyle and habitat Sensing Locomotion Food type ingestion and digestion Internal transport circulation O2 CO2 exchange respiration Getting rid of metabolic waste excretion Water balance osmoregulation Defense mechanisms Reproduction Be able to list what each animal does Basal Animals Porifera Sponges Phylum Porifera the Sponges o Basal animals basal metazoans o Aquatic mostly marine o Lack overall symmetry Sessile as adults grows attached to an organism o Sponges are filter feeders feed by passing water across structures that trap tiny food bits Water flows through pore cells into inter chamber called spongocoel Video fluorescent dye passing through pores quickly Choanocytes create currents trap and ingest food bits phagocytosis Food bits get moved to main body and ingested by phagocytosis intracellular digestion Amoebocytes distribute food Transferred to amoebocytes Jellylike part amoeboid movement to distribute food to other cells in the sponge All digestion intracellular o Lack true tissues Feeding digestion gas exchange waste removal all at cellular level 33 4 Learn the parts and their functions o o Cell types often change roles Spicules secreted by amoebocytes Choanocytes amoebocytes pore cells Body supported by hard spicules and protein fibers spongin Made by amoebocytes in mesohyl Reproduction By fragmentation Sexually hermaphroditic M or F at different times No gonads gametes form in mesohyl Flagellated larvae disperse then settle Basal Eumetazoans Cnidaria Phylum Cnidaria refers to the way they get food o Radial symmetry o Aquatic in two adult body forms Sessile polyp Drifting free swimming medusa o Aquatic sit and wait carnivores Stinging tentacles around central mouth catch prey and cnidocytes Video don t reach for prey have to make direct contact with tentacles before they can catch prey o Sac like body with gastrovascular cavity Gastro 1 opening mouth anus to digestive sac Extracellular and intracellular digestion Vascular g v cavity distributes nutrients to entire body o Diploblastic with gel mesoglea in between layers Direct O2 CO2 exchanging between cells and water Metabolic waste easily diffuses out Moving with nerve cells and have muscle fibers in epidermal cells Epidermis and gastrodermis have contractile cells coordinated by a simple nerve net Medusa e swim by contractions of their bell form o Reproduction sexual and or by budding Many cycle through polyp form and medusa form Ex Obelia All diploid Zygote through cleavage Flagellated larvae to get to new location Initiate transformation of form into polyp Gastrointestinal cavity Medusa develops the gonads Cnidarian Diversity o Freshwater Cnidarian Hydra o o Portuguese man of war is a colony of polyps marine Jellies jellyfish are marine and free swimming Bioluminescent Ex Corals sea anemones box jellies Basal Eumetazoans Ctenophora Phylum Ctenophora o Comb jellies are radially symmetric and diploblastic Transparent medusa like body Moves with cilia fused into 8 comb like plates o Marine sit and wait carnivores Only two tentacles or none Cells eject a sticky thread to capture prey Lophotrochozoans Platyhelminthes Phylum Platyhelminthes flatworms o Flat triploblastic acoelomate with bilateral symmetry Mesoderm derived muscle tissues o Thin body means high SA V ratio O2 CO2 exchange is at cell level Metabolic wastes removed at cell level o Many organs Gastrovascular cavity with 1 opening Highly branched to distribute nutrients Muscular pharynx suck in food for digestion Shows something about a nervous system with real nerve cords Simple nervous system Eyespots detect light avoid the light Ganglia simple brain Ventral nerve cords Protonephridia with flame bulbs remove excess water and some wastes o Flatworm diversity Planarians Free living carnivores or scavengers Trematodes flukes Parasitic on animals and with complex life cycles To complete life cycle they have to go through two or more hosts Ex Schistosoma blood flukes cause schistosomiasis Tapeworms Parasitic mostly in vertebrate intestines No mouth or digestive system absorptive Anterior scolex for attachment Repeated reproductive segments proglottids fill up with eggs Lophotrochozoans Rotifera Phylum Rotifera rotifers rotating bearing Free living aquatic Microscopic cylindrical body Rotating wheel of cilia brings plankton to mouth Uses cilia to generate a current pulls planktonic foods Well developed organ systems Alimentary canal mouth tube anus Flow thru food processing Specialized digestive regions Pseudocoelom acts as circulatory system Food digested here delivers nutrients to the body No blood vessels at all Many species only reproduce by parthenogenesis Lophotrochozoans Ectoprocta and Brachiopoda o Two Lophophorate Phyla o Common features Aquatic sessile suspension feeders using a lophophore Horseshoe ring of mucus coated ciliated tentacles trap and move food bits to mouth U shaped alimentary tract No head True coelom Phylum Ectoprocta o outside anus o Mouth at base of lophophore to bring mucus in o Bryozoans or moss animals Colonial mostly marine Most with mineralized exoskeleton Phylum Brachiopoda o brachiopods or lampshells Lophophore as feeding apparatus Marine with two shells analogous to bivalve mollusks and pedicle for attachment suspension Very diverse in fossil record few species today Lophotrochozoans Mollusca Phylum Mollusca o Common body plan Muscular foot locomotion digging used for burrowing functional equivalent to legs Visceral mass internal organs Well developed organ systems kidney rid of metabolic wastes gets fluids past through kidney Open circulatory system most have a heart and vessels Mantle covers visceral mass makes shell if present and pearl Tissue layer job is to protect visceral mass Forms mantle cavity with gills or lungs O2 CO2 exchange o Other mollusk features Shell present in most mollusks Secreted by mantle tissue CaCO3 in a protein matrix Many feed with radula Scrapping up food teeth made of chitin Modified in some Most with separate sexes except snails Most aquatic species with lochophore larvae mouth to anus digestive tract Land snails produce shelled eggs Many snails are hermaphroditic Eggs laid by aquatic apple snails