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Radiate Phylum >9,000 fossils >700 mya

specialized cells (cnidocytes)  specialized stinging organelle, the nematocyst

Phylum Ctenophora <100 species comb jellies/sea walnuts

Unicellular (acellular) Multicellular (metazoa)

protozoan protists

Poorly defined Diploblastic Triploblastic tissue layers Cnidaria Porifera Ctenophora Placozoa

Uncertain Acoelomate Coelomate Pseudocoelomate

Priapulida Rotifera Chaetognatha Platyhelminthes Nematoda Gastrotricha Rhynchocoela (Nemertea) Kinorhyncha Entoprocta Mesozoa Acanthocephala Loricifera Gnathostomulida Nematomorpha

Protostomes Uncertain (misfits) Deuterostomes

Annelida Mollusca Echinodermata Brachiopoda Arthropoda Hemichordata Phoronida Onychophora Bryozoa Chordata Pentastomida Pogonophora Sipuncula Echiura

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Cnidarian Characteristics 1) diploblastic: two well-defined germ layers: ectoderm & endoderm mesoderm may be derived from ectoderm (ectomesoderm) 2) internal body cavity: the gastrovascular cavity 3) extracellular digestion occurs in the gastrovascular cavity; gastrodermal cells enzymes for cellular digestion 4) nerve cells; nerve net but no central nervous system 5) sense organs: statocysts & ocelli 6) locomotion by muscular contraction : outer longitudinal & inner circular 7) unique feature: nematocysts (epidermis/gastrodermis) 8) tentacles: extensible projections for food capture with abundant nematocysts

9) all aquatic/mostly marine shallow marine environments some fresh water none terrestrial 10) some symbiotically e.g. with algae in reef-building corals 11) radial symmetry: oral & aboral ends 12) dimorphism: free-swimming medusae & sessile polyps: ecological niches 13) some: exoskeleton or endoskeleton: chitinous, calcareous or protein 14) gastrovascular cavity: a single opening serving as both mouth & anus 15) reproduction: either asexual or sexual 16) planula larva may be present 17) no excretory or respiratory system 18) no coelomic cavity

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Five Classes I. Hydrozoa

Ectopleura

Hydra: freshwater species no medusa stage budding

Corymorpha

Hydroids

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Polymorphism

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Craspedacusta

freshwater hydrozoan

Portuguese Man of War Physalia physalis

colony of polyps & medusae gas float

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II. Scyphozoa (true jellyfish)

scyphozoan medusa no velum thicker mesoglea aids in buoyancy

III. Staurozoa stalked jellyfish (only ) no medusa

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IV. Cubozoa

V.

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Hard Corals

Hard Stony Corals

cup coral Tubastrea sp. closed during day open during night Montastrea cavernosa polyps zoantharian

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soft octocorals 8 pinnate tentacles endoskeleton spicules with horny protein provides flexibility

spicule

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Corals restricted habitats shallow depths warm temperatures

Limiting factors sunlight photosynthesis water clarity

Dying Coral Reefs human impact pollution development global warming

Horny (gorgonian) Corals

red gorgonian Melithaea sp. sea fan Subergorgia mollis red whip Ellisella sp.

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Soft coral Dendronephthya sp.

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