BIOL 2325 Chapter Notes - Chapter 7: Nerve Net, Female Sperm, Digestion
Document Summary
Contain specialized stinging organelle (cnidae and nematocyst) 2 body types- free swimming medusa or sessile polyps. Mesoglea-extracellular matrix that lies between epidermis and gastrodermis. 5 classes: hydrozoa, scyphozoa, cubozoa, anthozoa, starutozoa. Polyp-tubular body and mouth upwards surrounded by tentacles. In colonial forms: polyps may be specialized for feeding(gastrozooids), reproduction(gonozooids), and defence(dactylozooids) Mouth is directed downward and tentacles outwards from rim of umbrella. Medusa contract bell and expel water(like a jet) Hydras can move across a substrate on their pedal disc. Planula metamorphosizes into a polyp(polyp reproduces asexually to produce medusas) Medusae- dioecious(separate sexes in the same organism), reproduce sexually. Cnidaria body- outer epidermis and inner gastrodermis. Water enters into gastrovascular cavity due to cilia(water helps to keep form of the body) Epitheliomuscular cells form most of epidermis and cause muscular contraction. Undifferentiated interstitial cells- develop into cnidoblasts, sex cells, buds or nerve cell but not epitheliomuscular cells.
