BIO 2135 : Cnidaria Key Words.doc
Document Summary
Aboral surface: in radially symmetric animals there is no anterior, posterior, left or right sides to the animal. In this case, it is the side opposite the mouth. Acontia: threadlike defensive organs composed largely of nettling cells, thrown out of the mouth or special pores of certain cnidarians when irritated (found at the base of anthozoan"s gastrovascular cavity). Anthozoa: include anemones and corals that have a polyp only life cycle. They are big and need to take in a lot of food (siphonoglyphs). Biradial symmetry: the organism appears radially symmetric but at least one set of structures is paired. This results in only two planes of symmetry that pass through the oral-aboral axis of the animal. Blastula: a stage in the development of multicellular animals in which only one cell layer is present, the blastoderm; the cavity the cells surround in the blastocoel.