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Zoology
WCHS Zoology Chapter 9 Cnidaria
Word | Definition |
---|---|
Cnidaria | the phylum of animals whose members are characterized by radial or biradial symmetry, diploblastic organization, a gastrovascular cavity, and nematocysts, jellyfish, sea anemones, and their relatives |
epidermis | a sheet of cells covering the surface of an animal's body; in invertebrates, a single layer of ectodermal epithelium |
gastrodermis | the endodermally derived lining of the gastrovascular cavity of Cnidaria |
mesoglea | a gel like matrix between the epidermis and gastrodermis of cnidarians |
polyp | the attached, usually asexual, stage of a cnidarian |
cnidocytes | the cells that produce and discharge the chidae in members or the phylum Cnidaria |
cnida | an organella characteristic of the cnidaria thaat is used in defense, food gathering and attachment |
nematocysts | a cnidarian cnida usually armed with spines or barbs and containing a venom that is injected into a prey's flesh |
medusa | usually, the sexual stage in the life cycle of cnidarians, the jellyfish body form |
gastrovascular cavity | the large central cavity of cnidarians and flatworms that recieves and digests foods. Has a single opening serving as both mouth and anus |
hydrostatic skeleton | the use of body cavity fluids, confined by the body wall, to give suport, also called hydroskeleton |
planula | a ciliated, freeswimming larva of most cnidarians, the planula develpos following sexual reprocution and metamorphoses in to a polyp |
gastrozooid | a feeding polyp in a colonial hydrozoan |
gonozooid | a polyp of a hydrozoan cnidarian that produces medusae |
gonionemus | a hydrozoan in which the medusa stage predominates, it lives in shallow marine waters where it often clings to seaweeds by adhesive pads on its tentacles |
obelia | small medusae from on a stalklike structur3e of the gonozooid, when mature break free and swimout an opening at the end of the gonozooid |
manubrium | a structure tath hangs from the oral surface of a cnidarian medusa and surronunds the mouth |
statocyst | an organ of equilibrium and balance in many invertebreates, usually consit of a fluid-filled cavity containng sensory hairs and a mineral mass called statolith, stimulates the sensory hairs, which helps orient the animal to the pull of gravity |
hydra | a common freshwater hydrozoan that hangs from the underside of floating plants in clean streams oand ponds, lacks a medusa stage and reproduces both asexual by budding from the side of the polyp and sexually |
aurelia | a common scyphozoan in both Pacific and Atlantic coastal waters of North America, the margin of its medusa has a fringe of short tentacles and is divided by notches |
rhopalium | a sensory structure at the margin of the scyphozoan medusa, it consists of a statocyst and a photoreceptor |
ephyrae | Miniature medusa produced by asexual budding of a scyphistoma, ephyrae mature into sexually mature medusae |
scyphistoma | the polyp stage of a scyphozoan, develps from a planula and produces ephyrae by budding |
protandry | the condition in a monoecious (hermaphroditic) organism in which male gonads mature before female gametes, prevents self-fertilization |