| A | B |
|---|
| bilateral symmetry | Portions of the body are specialized and only two planes of sectioning can divide the animal into perfectly similar halves |
| tissue | cnidaria level of organization |
| cnidocytes | stinging cells located along the tentacles of cnidarians; used for defense and to capture prey |
| nematocysts | stinging organelles |
| polyps | cylindrial forms that adhere to the substrate by the aboral end of the body |
| medusa | have a bell shaped or unbrella shaped body; the layer of mesoglea is very thick and constitutes most of their bulk |
| gastrovascular cavity | An extensive pouch that serves as the site of extracellular digestion and a passageway to disperse materials throughout most of an animal's body. |
| nerve net | nervous responses in cnidarians are controlled by a diffuse web of interconnected nerve cells |
| budding | asexual reproduction in which a part of the parent organism pinches off and forms a new organism |
| fission | form of asexual reproduction in which an organism splits into two, and each half grows new parts to become a complete organism |
| ectodermal | epidermis |
| mesoglea | in cnidarians, the jellylike material located between the ectoderm and the endoderm |
| operculum | lid covering cnidae |
| cnidoblasts | cnidocyte |
| statocysts | simple organs that detect gravity, enabling cnidarians to stay upright |
| Class Scyphozoa | they spend most if not all their lives as medusae |
| Class Hydrozoa | includes animals which spend part of their lives in both the medusa and polyp form; hydra is the exception and spends its entire life as a polyp |
| Class Cubozoa | includes box jellies and sea wasps, the medusa is box shaped and has complex eyes, often have highly toxic cnidocytes |
| Class Anthozoa | no alternation of generations the medusoid phase being entirely suppressed: sea anemones, corals |
| cnidarians | invertebrates that have stinging cells and take food into a central body cavity |
| sessile | describes an organism that remains attached to a surface for its entire life |
| hydra | a genus of small simple fresh-water predatory animals possessing radial symmetry belonging to the phylum of stinging-celled animals and the class Hydrozoa. |
| budding | asexual reproduction in which a part of the parent organism pinches off and forms a new organism |
| epithelial cells | Cells arranged in layers and covering or lining a surface of the body. |
| Class Scyphozoa | 90% medusa (large 10-50 cm), 10% polyp. mouth and reproductive parts hang down. all marine. |
| Class Anthozoa | "Flower Animal" anenomes/corals, (sea anemones and corals). live exclusively as polyps, but are more complex and they have a pharynx |
| medusa | free floating/swimming stage. sexual reproduction. |
| polyps | sessile stage. asexual reproduction. |
