BIOL 2001 Lecture Notes - Lecture 5: Pedal Disc, Coral Bleaching, Gastrovascular Cavity
12 Nov 2018
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Document Summary
They have a gastrovascular cavity with a single opening, surrounded by tentacles. They have cnidocytes containing the secretory organelle cnidae that are used for prey capture and defence from predators, most common type of cnidae is nematocyst. Cnidaria have 2 types of body forms (are dimorphic): 1-1-anthozoa: flower-like appearance, are carnivores, have pedal and oral discs for attachment and feeding, have large gastrovascular cavity with septa (extensions of body wall). Zooxanthellae (single-celled eukaryotes plankton) that produce up to. 90% of energy used by corals. (coral bleaching occurs when corals are stressed to the point of releasing their mutualistic zooxanthellae. ) 1-3-hydrozoa (polyp forms of some scyphozoa and cubozoa also might exist) 1-gastrozooid: feeding polyps with mouth and tentacles for prey capture. 2-dactylozooid: defence polyps with tentacles but no mouth. 3-gonozooid: reproductive zooids with no mouth (male or female). Organelles in unicellular eukaryotes that function very much like nematocyst (cnidae).
