Transcript Zoology - Central Lyon CSD

Zoology
Phylum Cnidaria
I. Intro to Cnidarians
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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 Hyrdrozoans
1. 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 Anthozoan
A. Facts
1. meaning  “flower animal”
2. No medusa stage
3. Only marine
4. octomerous – 8 tentacles
5. hexamerous – 6 tentacles
B. Notable Anthozoans
1. 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