Systematic Adaptations of Phylum Cnideria The Jellies, Anemone and Corals

Objectives (Chapter 13) 1. Identify characteristics distinguishing phylum Cnideria 2. Discuss adaptations characteristic of the phylum Cnideria with regard to Body form, morphology & embryonic development Feeding and digestion Excretion Movement/locomotion Reproduction Sensory/Motor response 3. Define “dimorphism”. Distinguish between the polyp and medusa form of Cniderians

Objectives (Chapter 13) 4. Describe structure and function of cnidocytes 5. Distinguish between the taxonomic Classes in the Phylum Cnideria. Give examples 6. Discuss the ecological significance and development of coral reefs 7. Compare & Contrast Ctenophores with Cniderians

1. Identify characteristics distinguishing phylum Cnideria Radial symmetry Tissue level of organization Incomplete gastrulation (one opening to the digestive cavity) Diploblastic Endoderm and Ectoderm only – No mesoderm Tentacles with stinging “cnidocytes”

2. Discuss adaptations characteristic of the phylum Cnideria Body form, morphology & embryonic development Feeding and digestion Excretion Movement/locomotion Reproduction Sensory/Motor response

Body Form & Development

Body Form and Development Epidermis Derived from embryonic ectoderm Gastrodermis Derived from embryonic endoderm Mesoglea Middle jelly Tentacle With cnidocytes

Dimorphism Medusae Bell Shaped Motile Usually sexually reproducing Jellyfish Polyps Tube shaped Sessile Usually asexually reproducing Anemone and Corals https://www.youtube.com/watch?v=Szt42nG-hGg

Integumentary & Muscular Epidermis is a single cell layer Muscle fibers associated with the base of the epithelium True muscle is mesodermal in origin. Cnideria are diploblastic (no mesodermal tissue) Movements are simple and non-specific

Nervous & Sensory No central nervous system Nerve cells in a diffuse “nerve net” ennervate the epitheliomuscular cells https://www.youtube.com/watch?v=7fScolnOCtI

Digestive One opening to the digestive cavity Digestive enzymes secreted by the gastrodermis (“extracellular” digestion) https://www.youtube.com/watch?v=bcmL xsJ5SAg

Reproduction Cnideria have a variety of life cycles, from simple to complex. Generally, the polyp form is used for asexual reproduction. https://www.youtube.com/watch?v=hXaswpUjK-M https://www.youtube.com/watch?v=bcQs3dkrH0A Sexual reproduction occurs in the medusae https://www.youtube.com/watch?v=8zSZtZDwabo https://www.youtube.com/watch?v=Id53jmsdxfQ Both monoecious and dioecious forms exist,

Characteristic Cniderian Life Cycle

Cnidocytes https://www.youtube.com/watch?v=6zJiBc_N1Zk https://www.youtube.com/watch?v=-Tp38DUjUnM

Cniderian Classes Hydrozoa Scyphozoa Cubozoa Anthozoa Asexual polyps, sexual medusae Polyp stage reduced or absent Polyp stage reduced All polyps, medusae absent “velum” at the rim of the bell in the medusae to aid propulsion Medusae lack a velum. Bell margin with sense organs Cube shaped medusae. No velum, but “vellarium” with similar function Cnidocytes in the gastrovascular cavity See the life cycle diagram on page 261 in the textbook Enlarged mesoglea (the “jelly” in the jellyfish”) Blade shaped “pedalium” at the base of the tentacles Septa (mesenteries) separating gastrovascular cavity Freshwater and marine All marine Hydra, Portugese Man of War What we think of when we think of jellyfish Very poisonous. Stings may be fatal to humans Corals and Anemone

Hydrozoa https://www.youtube.com/watch?v=yqXkaZwiu6s https://www.youtube.com/watch?v=9MEt0Ot7Pkc https://www.youtube.com/watch?v=zPdkxdu9rfs https://www.youtube.com/watch?v=RBdCpcapB0s

Scyphozoa https://www.youtube.com/watch?v=1oIBwWY04ZI&list=PLdHUIRuQuOel4SQpONiusXIA4taUC0Wgk&index=4

Anthozoa https://www.youtube.com/watch?v=a2m59UoTEgs https://www.youtube.com/watch?v=z0Q7LgAgW1k

Cubozoa https://www.youtube.com/watch?v=CCuNMIT67y8

Coral Reefs https://www.youtube.com/watch?v=eIul2ObvKV8 https://www.youtube.com/watch?v=wbNeIn3vVKM

Ctenophores (Comb Jellies) Superficially similar to Cniderian medusae, but: “Comb plates” for locomotion No nematocysts True muscle (derived from mesoderm?) Complete digestive tract https://www.youtube.com/watch?v=Wc11fhK4o90 https://www.youtube.com/watch?v=icKB9EfURhQ https://www.youtube.com/watch?v=Qy90d0XvJlE

Video Links Great Barrier Reef Documentary (long!) Cniderian Diversity https://www.youtube.com/watch?v=EueBzS3kPe8 Cniderian Diversity https://www.youtube.com/watch?v=6VAp7DHut_E Cniderian Movement https://www.youtube.com/watch?v=sJn8vB5hBOQ