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4/7/2011 Invertebrates • 95% of all known animals • Mammals, birds, reptiles, amphibians, and fishes are a small part of animal diversity Invertebrate Diversity Invertebrate Diversity Phylum Placozoa • One Species: Trichoplax adhaerens • A few thousand cells, no organs • Mostly asexual reproduction “Sponges” • 2 Phyla: Calcarea and Silicea • Filter Feeders • No true tissues – Cell Types: Choanocytes (collar cells): Feeding cells, with flagella Amoebocytes: digestion, food transport, skeletal production 2 cell layer, separated by gelatinous mesohyl “Sponges” • 2 Phyla: Calcarea and Silicea • No true tissues • Suspension Feeders “Sponges” • Reproduction – Hermaphroditic (both sperm and eggs) – Sequential – Gametes from choanocytes Gametes from choanocytes or amoebocytes or amoebocytes • Sperm released, carried into other individuals • Zygote develops into flagellated, swimming larva • Some produce antibiotics 1 4/7/2011 Phylum Cnidaria Phylum Ctenophora (Comb Jellies) • True Tissues: Diploblastic • Radial Symmetry • 8 “combs” of cilia Phylum Cnidaria • True Tissues: Diploblastic • Radial Symmetry • Two basic body plans Phylum Cnidaria – 4 Classes • Carnivorous • Cnidocytes Cubozoa – Contain cnidae • exploding organelles – Some specialized into nematocysts • Venomous Hydrozoa • Mostly Marine Scyphozoa Anthozoa Phylum Cnidaria – 4 Classes Phylum Cnidaria – Reproduction • Cubozoa Defenses 2 4/7/2011 Phylum Acoela • Bilateral symmetry • Simple flatworms • Formerly placed with Platyhelminthes with Platyhelminthes Phylum Platyhelminthes • Flatworms; Acoelomate – Turbellarians: Free Living Phylum Platyhelminthes • Parasitic Flatworms – Monogeneans, Trematodes, Tapeworms – Mimic surface proteins Blood fluke Blood fluke Lophotrochozoa • Triploblastic • Bilateral Symmetry • 18 phyla Phylum Platyhelminthes • Parasitic Flatworms – Monogeneans, Trematodes, Tapeworms – External parasites of fish Phylum Platyhelminthes • Parasitic Flatworms – Monogeneans, Trematodes, Tapeworms Live in intestine: no mouth Up to 0 Up to 20m 3 4/7/2011 Phylum Rotifera • • • • Small (max 2mm) 2 opening digestive tract Pseudocoelomate Many use parthenogenesis only Phylum Mollusca Lophophorates • Lophophore • Phylum Ectoprocta – “Bryozoans” • Phylum Brachiopoda • Coelomate Phylum Mollusca • Soft‐bodied, many secrete shell • Coelomate • Foot, visceral mass, mantle – Some have mantle cavity • Contains gills, anus, excretory pores • Many have a radula – Scrapes food • Many have trochophore larva Phylum Mollusca • Class Polyplacophora – Chitons – Shell w/ 8 plates • Scrapes algae with radula Phylum Mollusca • Class Gastropoda – Snails, Slugs, Nudibranchs • Torsion – 180° twist during development • Many eat algae or plants – Some modified radula for drilling or as poison dart • Shell present in snails 4 4/7/2011 Phylum Mollusca Phylum Mollusca • Class Bivalvia – Oysters, Mussels, Scallops, etc. • Shell w/ 2 halves; adductor muscles • No radula; filter feeders • Class Cephalopoda – Squid, Octopi, Nautili • Active predators, fast movements • Shell reduced/internal or absent – Except nautilus Video • Closed circulatory system • Tentacles and beak • Good eyes, smart Phylum Mollusca • Class Cephalopoda – Squid, Octopi, Nautili – Can get to enormous size – Move by shooting water jets through water jets through excurrent siphon Phylum Annelida • Segmented Worms • Coelomate • Up to 3m Phylum Annelida • Oligochaetes – Earthworms – Few bristles (made of chitin) – Extract nutrients from soil • Polychaetes P l h t – Many bristles M b i tl – Mainly marine • Leeches – Predators and parasites Phylum Annelida • Clitellum – Secretes mucus, which picks up eggs and sperm gg p • Some can reproduce by fragmentation 5