phylum cnidaria or coelenterata
TRANSCRIPT
Phylum Cnidaria or Coelenterata
Cnidaria
� Definition: � Cnidaria: Stinging Cells
� Cnid = nettled, aira = plural� Nettled = covered with stinging hairs
� Coelenterata: Hollow-gut
� Common Example: � Jellyfish� Sea anemone � Coral
Characteristics
A. Body plan is sac-likeB. Internal body cavityC. Extracellular digestion in the
gastrovascular cavitygastrovascular cavityD. Biradial SymmetryE. Extensions from the body. Tentacles
used for � food capturing � defense
Characteristics Cont…
F. Sense organs appear first then radiates as ocelli (light sensitive)
G. LocomotionLocomotion� Muscular contractions� Free floating� Summersaults
H. True Nerve cells for a Central Nervous System
Classes Hydrozoa
Greek Meaning Water Serpent• hydra = water and • zoan= animal
• Solitary animal• Solitary animal• Colonial meaning found in groups• Fresh and Marine water• Example: Brown Hydra, Green Hydra,
Obelia
Green Hydra
Brown Hydra
Obelia
Scyphazoa
� Greek Meaning Skyphos = cup and zoan = animal
� Solitary only in the polyp stage� Solitary only in the polyp stage� Bell shape body� Mesoglea layer� Medusa (tentacles extend down)
Class Scyphozoa
� Examples� Jellyfish, � Aurelia� Aurelia� By the Wind
Sailor
Jellyfish
Aurelia
By the Wind Sailor
By the Wind Sailor
Class Anthozoa
� Greek Meaning � Anthos = flower � Zoan = animal� Zoan = animal
� All polyps� No Medusa� Solitary or Colonial� Sessile
Anthozoa
� Examples� Sea anemone� Coral� Coral
� Polyps are attached or sessile
Class Notes
sessile
� stalk-like structure
Class Notes
� Medusa are free floating and muscle muscle contractions
� Bell-shaped body
Class Notes
� Entirely Aquatic
� No excretory system or respiratory systemsystem
� Exoskeleton made of chiton or lime
Class Notes
� Food and Defense
� Cnidocytes (stinging cells)� Single cell
� Flagella like structure with barbs = nematocysts
Cnidocytes
� When the hair-like trigger is activated, the shaft of the cnidocyst penetrates the target organism, and the hollow thread is everted into it
� Takes no more than a few µs,
Cnidocyte Action
� Takes no more than a few µs, and is able to reach about 40,000g
� Recent research suggests the process to occur as fast as 700 nanoseconds
� After penetration, the neurotoxin content of the nematocyst is injected into the target organism immediately paralyzes the mobile prey, thus allowing the sessile cnidarian to devour it
Portuguese Man of War
� Not a true Jellyfish� Order of the class Hydrozoa –
SiphonophoraeSiphonophorae� Appears to be a single organism, but is
a colony of cells
Portugese Man of War
Terms��PolypPolyp
��MedusaMedusa
��NematocystsNematocysts
��Gastrovascular CavityGastrovascular Cavity
��MesogleaMesoglea
��CnidocytesCnidocytes
��TentaclesTentacles
What class do hydra belong to?
What Phylum do Jellies belong to?
Jellyfish Attack
What Phylum does Coral belong to?
What are the stinging cells called?