Lab Exercise 4 Porifera Cnidaria Platyhelminthes Organization in Animals • Cellular level: Random assembly of cells • Tissue level: Cells connected to form distinct tissues • Organ level: Tissues connected to form organs Levels of Biological Organization • Organ system level – All more advanced organisms – Multiple organ systems working together form an complex organism 1 Biological Symmetry • Radial Symmetry – Body can be divided into mirror image halves through the center –Examples • Mature Cnidarians Biological Symmetry • Bilateral Symmetry – Body is divisible into left and right halves by a single plane only –Examples •Flatworms • Arthropods • Vertebrates Biological Symmetry • Asymmetry – Body cannot be divided to produce mirror image halves –Example • Porifera 2 Embryonic Development Cell Cleavage Blastula Gastrula Gastrula Gastrula Gastrula (Diploblastic) (Triploblastic) Ectoderm Endoderm Mesoderm Archenteron- Space within endoderm Blastopore Blastopore Archenteron: becomes adult digestive tract Blastopore: becomes the mouth or anus Phylum Porifera • Diploblastic • Asymmetrical • No digestive tissue- absorbs particles from water 3 Phylum Porifera Ostium • Ostium • Choanocytes • Amoebocyte • Spicules • Spongocoel • Osculum Phylum Porifera— 3 Body Plans Asconoid Syconoid Leuconoid Phylum Cnidaria • Characteristics – Radial symmetry – Cnidocytes – Simple nerve net – Life cycle alternates between two forms • Medusa •Polyp 4 Cnidaria - body plan Polyp Medusa Cnidocyte Operculum Cnidocil Cnidocyte Nematocyst Class Hydrozoa - Hydras • Polyps are the mature form • Individuals or colonies • Portuguese Man-o- war special colony 5 Class Hydrozoa - Hydras • Prey on zooplankton • You will observe Hydra feeding on Daphnia – Look at locomotion http://www.youtube.com/watch?v=Kukv0AtIVdU Class Scyphozoa: Jellyfish •Marine Mesoglea Gastric pouch Gonad • Medusas: dominant life form • Aurelia Tentacles Ectoderm Endoderm Oral arms 6 Class Anthozoa • Anemones and corals • Most complex cnidarians • Always polyps • Symbiosis with dinoflagellates Class Anthozoa - Anemones pharynx coelentron basal http://www.emc.maricopa.edu/faculty/farabee/biobk/anemone.gif Phylum Platyhelminthes- Flat worms •Triploblastic • Bilateral Symmetry •Organs • Sac-like gut •Acoelmate –No cavity • Monoecious 7 Class Turbellaria– Planarian spp. • Free living • Cephalization- – You can see where you are going – Brain center- coordinate movement • Bilateral Symmetry = efficient movement Class Turbellaria Planarian cross-section Ectoderm Mesoderm Endoderm Pharyngeal cavity Pharynx Gut Gut Lumen of the pharynx Parenchyma Class Trematoda-Flukes • Life cycle with multiple hosts • Parasites – Opisthorchis sinensis- Human liver fluke 8 Class Cestoda- Tapeworms • Thin, ribbon-like • Sections = proglottids • Parasites • 1 or 2 Hosts Class Hydrazoa Gonangia Hydranth Class Scyphozoa 9 Class Trematoda • Life cycle with multiple hosts 10.