zoology phylum cnidaria. i. intro to cnidarians cnidocytes/nematocysts “stinging organelles”...
TRANSCRIPT
Zoology
Phylum Cnidaria
I. Intro to Cnidarians Cnidocytes/nematocysts “stinging
organelles” Ancient group dating back 700 million
years Mostly marine / non-terrestrial Sessile lack movement Free floaters Effective predators Ex: Jellyfish, anemones, stony corals
II. Class Hydrozoa
A. Facts
1. Both Medusa and Polyp stages
2. Reproduce sexually and asexually
B. Notable Hyrdrozoans1. Hydra – small freshwater organisms
-polyp form only-25-30 mm in length-shares a mouth and anus-sessile … attach to plants,rocks,
etc. tentacles sway in the current
-tentacles (6-10) contain nematocysts = stinging cells release neurotoxins
paralyze prey
a. 3 types of nematocysts
1st – penetrants
penetrate and inject poison
2nd – volvents
recoil and entangle prey
3rd – glutinants
secrete adhesives (used in movement and locomotion)
b. Favorite Prey of Hydra
-Daphnia
-worms
-small insects
-small crustaceans
2. Portuguese Man of War
a. Pneumatophore – sac like structure filled with gas
-allows movement (wind + water currents)
III. Class AnthozoanA. Facts
1. meaning “flower animal”2. No medusa stage3. Only marine4. octomerous – 8 tentacles5. hexamerous – 6 tentacles
B. Notable Anthozoans1. Sea Anemone
-very colorful-prefer warmer waters
a. Mutualistic Relationships
-hermit crabs – attach to backs
provides protection
gets small morsels of food
-clownfish – skin mucous prevents nematocysts from stinging
provides protection
lures unsuspecting fish in
IV. Class Scyphozoa
A. Facts
1. Common Jellyfish
a. “Scypho” = cup animals or bell shaped
2. Found in all oceans
3. Notable Scyphozoans
a. Cassiopeia
-floats upside down
B. Note – box jellyfish is not found in this class
class cubozoa