Phylum Coelenterata (Cnidaria & Ctenophora) Fig. 13.CO

Phylum Cnidaria Diploblastic organisms Radially symmetrical Dimorphic Cnidocytes ~10,000 species Aquatic

Taxonomic Characteristics Diploblastic Gastroderm & Musculo-epithelial tissues

Taxonomic Characteristics Incomplete digestive tract Coelenteron

Taxonomic Characteristics Decentralized nervous system

Taxonomic Characteristics Cnidocytes

Hydrozoan stinging and capturing prey Everted nematocyst Hydrozoan stinging and capturing prey Fig. 13.8

Cnidarian Dimorphism Fig. 13.2

Cnidarian Dimorphic Life Cycle Fig. 13.9 Colonial hydrozoan

Cnidarian Taxonomy Phylum Cnidaria Class Hydrozoa Class Scyphozoa Class Cubozoa Class Anthozoa

Class Hydrozoa Most varied of the cnidarian groups Includes freshwater species (Hydra spp) Colonial species common (Obelia sp) Most have typical dimorphic life cycle Polyp forms dominant (Hydra)

A typical Hydrozoan Hydra Lacks medusa stage Asexual - budding Sexual – gametes Planula larva

Colonial Hydrozoan - Obelia Colony of specialized hydranths Gonangia (gonozooids) – reproduction Gastrozooids – feeding Dactyolozooids – catching prey hydranths Fig. 13.1

Obelia –schematic diagram Portuguese Man-O-War (Physalia physalis) Polyp – air bag Feeding & reproductive hydranths - tentacles Obelia –schematic diagram

Colonial Hydrozoans Fire Corals NOT TRUE CORAL TRUE CORAL Hydrozoan colony TRUE CORAL Anthozoan colony Cnidocytes cause severe pain Fig. 13.15

Dimorphic Life Cycle and Reproductive Modes Asexual Budding Medusa buds Polyp buds Sexual Gonadal tissue Gametes Fertilization, embryogenesis Planula larvae Fig. 13.Fig. 13

Class Scyphozoa Typically thought of as jellyfish Most have typical dimorphic life cycle Polyp stage is atypical Majority of life cycle spent in medusa form

Scyphozoan Life Cycle Fig. 13.18

Jelly fishes Fig. 13.19

Lion’s Mane Jelly (Cyanea capillata)

Class Cubozoa Fig. 13.20

Class Cubozoa Chironex fleckeri Size of human head with tentacles (4) up to 9 ft long 18-24 ft of tentacles can deliver enough poison to kill in <5 min.

Class Anthozoa Anemones & Corals Lack medusa form; largely polyp Form colonies (especially coral)

Class Anthozoa – Typical Polyp Form Fig. 13.23

Class Anthozoa giant anemone or purple-tipped anemone (Condylactis gigantea) Often harbors cleaning shrimp among its tentacles

Anemone Coral & Anemone Fish Fig. 13.25

Fig. 13.26

Class Anthozoa – Hard Coral Hexacorallia – 6-fold symmetry Precipitate Ca3(CO3)2 from sea water become skeletal structures that become coral reefs Contain zooxanthelae Fig. 13.28

Class Anthozoa – soft corals Octocorallia – 8-fold symmetry Form complex tube-like skeletal structures Lack zooxanthella Fig. 13.31

Class Anthozoa – Soft Corals Fig. 13.32

Reefs Shallow tropical waters Hermatypic corals (Class Anthozoa, Subclass hexacorallia, Order Scleractinia) Contain symbiotic dinoflagellates Precipitate CaCO3 to form “exoskeleton” Fig. 13.34a

Phylum Ctenophora Comb-jellies <100 species Lack cnidocytes Rows of cells with fused cilia – comb-plates <100 species Lack cnidocytes Complete digestive tract

Ctenophore Morphology Fig. 13.36d

Ctenophore Morphology Fig. 13.36b

Ctenophore Body Forms Biradial symmetry Some are bilateral Two tentacle clusters Even # comb rows Some are bilateral Fig. 13.37

Bioluminescence