Phylum Cnidarians |
Characteristics-
Produce nematocysts (a barbed organelle)- to harm organisms
Cnidocyte – when trigger is stimulated the nematocyte is released
Contains:
trigger- to “feel” stimulus to release nematocyte
body sac- holds nematocyte
Nerve net- whole body reacts to any stimulation
Lacks central nervous system (brain)
Hydrostatic Skeleton- (water trapped) water moves in the mouth and is trapped by the mouth muscle (sphincter)
and the water pressure supports the body
2 Layered body wall
Epidermis- skin layer
Mesoglea- glue layer
Undifferentiated cells interstitial (means in and among) cells can become different types of cells
Predators that are stationary
Pharynx- “throat” opening that leads to gastrovascular cavity
Incomplete digestive systems (inefficient)- has only one opening (mouth)
Asexual Reproduction- Forming buds by mitosis, that become new polyps Sexual Reproduction- (Diecious- male and female medusa) Egg is fertilized by sperm Zygote is created Develop into blastula Develop into plantula larva Develop into polyps Polyps can branch – they have many feeding heads because they are one time use Only Reproductive polyps- gonangium – produces medusae Medusae swim, cluster and relese sperm and eggs into water to be fertilized
Class Anthozoa (anemones, corals, etc.) Class Hydrozoa (Portuguese Man o' War, Obelia, etc.) Hydra, Physalia Class Scyphozoa (jellyfish) Aurelia Class Cubozoa (box jellies) Class Scyphozoa (jellyfish) Aurelia Reproduce with medusa Modified polyp on gonangia Medusa- protein-atious (not cellular) mesoglea that makes jelly fish “jelly” Aurelia- common Atlantic jellyfish Chrysaora- Chesapeake Bay jellyfish\ Sea nettle Class Hydrozoa Gonads on side of body Asexual budding is common Obelia- has a typical life cycle of a Cnidarian Portuguese Man o' War- toxic venom- a colony of polyps Hydra – only polyp – no medusa Class Anthozoa Only polyps no medusa Form gonads inside polyps Gametes relased through mouth Form plantula larva Sea amemomies – Metridium Coral – produce CaCO3 skeleton
Clownfish and Anemone- have a mutialistic relationship, fish are not hurt by nematocysts
Lab Parts:
Hydra Polyps, freshwater polyps
Slides 29-32
Bud ________________________Embryo_____________________Ovary_________________Testes
Hydra cross section
Slide 45 Obelia
Has a "typical" Cnidarian life cycle
__________________________________________________SLide 46 Obelia medusa
Slide 33 Aurelia polyp scyphistoma
Home | Links | Projects | 19th Century Art | Biology | Cartography | Photos | Recipes | Resumè