BIOL 371 Lecture Notes - Lecture 7: Gastrovascular Cavity, Planula, Rhopalium
Document Summary
Include obelia-marine colonial hydrozoan, shaped kind of like a tree. Shared gastrovascular cavity where food flows to all members. Hydranths- have tentacles and are the feeding polyps. Gonangia- no tentacles and are the reproductive bodies. Eventually it buds off to make a new colony. Medusae have a velum which is an inward projecting shell which helps increase efficiency in swimming. A colony of polyps that chare a gas filled float. Have bells that range in shape from shallow dishes to deep bowls. Have scalloped edges which have the rhopalia( sensory cells) on it. Mouth extends down and is at the end of the manubrium. Oral arms capture the prey that goes into the mouth and then to the stomach. Stomach has gastro-pouches sticking out of the side. The pouches have filaments covered with nematocysts to further quiet the prey. Gonads develop within the pouches and then release their gametes into the water.
