CNIDARIA Flashcards
Cnideria; whats the greek meaning?
a stinging thread
Cnideria; which type of animals?
jellies, corals, sea anemones, hydroids
when did cnideria emerge?
800 mya
why do we regard Cnidaria as simple?
- no head end
- mouth=anus
- mouth surrounded by tentacles
- radial symmetry
- diploblastic
- nerves (no brain or CNS)
what tissue replaces mesohyl (porifera) in cnideria?
mesoglea
mesoglea
middle-jelly
what are all cells in contact with?
the environment
cell movement in cnidaria
- migratory stem cells (all cells are stem cells)
- nematocysts, nerve cells and gonads
what are the four class or cnidaria?
Anthozoa -anemones, corals Hydrozoa -Hydroids Scyphozoa -Jellyfish Cubozoa -box jellyfish
What stage (medusa/polyp) is dominant for each class of Cnidaria?
Anthozoa: no medusa stage. polyp.
Hydrozoa: medusa and polyp
Scyphozoa: medusa
Cubozoa: medusa
in which other phyla can you find nematocysts?
mollusca (nudibranch)
ctenophores
platyhelminthes
kleptocnidae
microsporidia and myxosporidia
protist origins of cnidaria. both parasitic, and either protist or fungi now
nerve conduction
- response times are slow
- concentration is slower
- can be up to 2 minutes before reaction
locomotion- anthozoa
- may shuffle, burrow or swim
- contract muscle by coelenteron
- pharynx, siphonoglyph
locomotion- scyphozoa
-tentacles
-change body shape
-medusa vs polyp
-muscle contraction and a skeleton
hydrostatic
mesoglea
contraction o striated muscles
ringed nerve cells
locomotion- hydrozoa
-velum. principle of continuity. (hose with your finger on it. thats how this animal moves)
locomotion- cubozoa
- rapid
- they sleep!
- 8 camera eyes
- nerve ring connection
- rhopalium
- hunt, kill, close to shore (danger!)
how do cnidaria reproduce?
sexually and asexually.
ALTERNATION OF GENERATIONS.
Medusa>Polyp
how do anthozoa reproduce?
Sexual:
broadcast spawning; fertilization in the water column.
Asexual:
logitudinal fission (split in 2)
parthenogenesis (basal laceration, internal basal laceration, brooding)
Hydrozoa; reproduction
- dioecious adults
- egg + sperm
- fertilization
- planula larvae
- settlement
- polyp colony growth
Scyphozoa; reproduction
- dioecious adults
- egg
- scyphisotoma
- ephyra
Cubozoa; reproduction
- dioecious
- pairs
- embryo
- planula
- polyp
- budding
- metamorphose
the three general formations of cnidaria
- polyp and medusa forms
- colony formation
- coral formation
4 parts of medusa anatomy
- bell
- gonads
- nerve ring
- radiating canal
