ROLL CALL 



ni 



PHYLUM III — COELENTERATA — Jellyfishes and corals. 



Characteristics: Mostly marine; radially syinniotrioal ; diploblastic- ani- 

 mals with a noncellular layer of niesoglea lying between; po.ssL's.sing 

 tentacles, armed with nematocysts; body composed of a single gastro- 

 vascular cavity ; 4500 species. 



Class I — Hydrozoa — Fresh-water polyps, jellyfishes, and a few stony corals 

 {Hydra, Obelia, Physalia). 

 Characteristics : Mostly marine ; usually hydroid and jellyfish forms 

 occur in the same life cycle; the jellyfish (medusae) po.ssess a shelflike 

 velum extending inward from the margin toward the mouth (manubrium) ; 

 a few species like Hydra possess no medusoid stage; the stony coral, 

 Millepora, represents a colony with a coral-like skeleton of calcium car- 

 bonate. 



Cl.\ss II — Scyphozoa — (Amelia). 



Characteristics: Entirely marine, with the medusoid stage dominating; 

 produced from subordinate polyp by terminal budding (strobilalion) ; 

 velum usually absent; lobate, typically eight-notched. 



Class III — Anthozoa — Sea-anemones, sea-pens, and stony corals (Metridium, 

 Pennatula, Astrangia, Sagartia). 

 Characteristics : Entirely marine with medusoid stage suppres.sed ; organ- 

 isms characterized by an introverted ectodermal mouth (sto7nodaeum) anti 

 vertical radiating mesenteries extending inward from the body wall; one, 

 two, or more rarely three cihated gullet grooves (siphonoglijphs) carry 

 a stream of oxygenated water to interior. Corals produce islands and 

 reefs; in addition they sometimes protect a shore from wave action. 



