Post on 27-Mar-2015
Kingdom AnimaliaKingdom Animalia
Phylum Cnidaria (Coelenterata) Phylum Cnidaria (Coelenterata)
http://videos.howstuffworks.com/hsw/11758-the-world-of-animals-phylum-cnidaria-video.htm
Two Body Forms Two Body Forms
Cnidarians include: Jellyfish, Sea Cnidarians include: Jellyfish, Sea Anemones, Hydras, and CoralsAnemones, Hydras, and Corals
All have radial symmetry (“little rings”)All have radial symmetry (“little rings”) Two body forms:Two body forms:
– Medusa- Free-floating, jelly-like and often Medusa- Free-floating, jelly-like and often umbrella shapedumbrella shaped
– Polyp- Tubelike and usually attached to a rock Polyp- Tubelike and usually attached to a rock or other surfaceor other surface
Two Body FormsTwo Body Forms
Tentacles surround mouth, located at free end Tentacles surround mouth, located at free end of body of body
Three layers of cells:Three layers of cells:– Outer layer from ectodermOuter layer from ectoderm– Inner layer from endodermInner layer from endoderm– Middle layer of mesoglea (jelly-like)Middle layer of mesoglea (jelly-like)– Cells arranged into tissuesCells arranged into tissues
Coelenteron-Coelenteron- digestive cavity where digestive cavity where enzymes digest foodenzymes digest food
Two Body FormsTwo Body Forms
Body FormsBody Forms
CnidocytesCnidocytes– Stinging cells located on Stinging cells located on
the tentaclesthe tentacles
– Distinguishing Distinguishing characteristic of Cnidarianscharacteristic of Cnidarians
– Small, barbed harpoon Small, barbed harpoon (nematocyst) within each (nematocyst) within each CnidocyteCnidocyte
– Used for defense or to spear Used for defense or to spear preyprey
– Toxins can be deadly or Toxins can be deadly or only stunonly stun
Extracellular digestionExtracellular digestion– Digestion begins Digestion begins
outside the cell in the outside the cell in the gastrovascular cavitygastrovascular cavity
– Enzymes break food Enzymes break food into smaller fragmentsinto smaller fragments
– Cells lining cavity Cells lining cavity engulf fragments and engulf fragments and finish digestion finish digestion intracellularlyintracellularly
http://video.google.com/videoplay?docid=-7505220246577159769&ei=QPWqSLrmO4OcrwLvmayYAQ&q=cnidarians&vt=lf&hl=enLrmO4OcrwLvmayYAQ&q=cnidarians&vt=lf&hl=en
Class HydrozoaClass Hydrozoa
Freshwater hydrozoaFreshwater hydrozoa– Genus Genus Hydra Hydra exist only exist only
as Polyps less than .4” as Polyps less than .4” longlong
– Attach to objects with Attach to objects with sticky secretion from the sticky secretion from the basal diskbasal disk
– Can glide on objects or Can glide on objects or tumbletumble
– Have a nerve net- Have a nerve net- branching system of branching system of nerves with no brainnerves with no brain
Class Hydrozoa Class Hydrozoa
Marine HydrozoaMarine Hydrozoa– Often live in coloniesOften live in colonies– Can be medusas or Can be medusas or
polypspolyps– Ex: Portuguese man-Ex: Portuguese man-
of-warof-war– PhysaliaPhysalia- floats on - floats on
water and dangles water and dangles tentacles with powerful tentacles with powerful neurotoxins (nerve neurotoxins (nerve poisons)poisons)
Reproduction in HydrozoaReproduction in Hydrozoa
Most hydrozoans are colonial and reproduce Most hydrozoans are colonial and reproduce asexually by buddingasexually by budding
Some species are sexualSome species are sexual– Most single sexes, but some hermaphroditesMost single sexes, but some hermaphrodites
Genus ObeliaGenus Obelia– Colonize a single polyp with budsColonize a single polyp with buds
– Reproductive polyps produce medusasReproductive polyps produce medusas
– Medusas reproduce sexually and produce ciliated Medusas reproduce sexually and produce ciliated larvae called planulae, which develop into new polyps larvae called planulae, which develop into new polyps
Obelia ReproductionObelia Reproduction
Class ScyphozoaClass Scyphozoa
True jellyfish and True jellyfish and active predatorsactive predators
Range from thimble Range from thimble size to queen-size size to queen-size mattressesmattresses
Mostly medusas which Mostly medusas which reproduce sexuallyreproduce sexually
Polyp stages early in Polyp stages early in lifelife
Jellyfish relatives:Jellyfish relatives:– Cubozoans- Small box-shaped medusas Cubozoans- Small box-shaped medusas
with tentacles on corner of “box”with tentacles on corner of “box”– Inconspicuous polyp stage Inconspicuous polyp stage – Ex: Box jellysish or Sea wasp can be Ex: Box jellysish or Sea wasp can be
deadlydeadly– Phylum Ctenophora- Comb jellies have Phylum Ctenophora- Comb jellies have
only a medusa stage and no only a medusa stage and no nematocystsnematocysts
» Class Tenaculata- with tentaclesClass Tenaculata- with tentacles» Class Nuda- without tentaclesClass Nuda- without tentacles
– Irukandji Jellyfish (Carukua Irukandji Jellyfish (Carukua barnesi)barnesi)
» 2.5 cm in diameter2.5 cm in diameter» Kills in daysKills in days
Jellyfish RelativesJellyfish Relatives
Class AnthozoaClass Anthozoa
Largest class existing only Largest class existing only as polypsas polyps
Includes anemones, coral, Includes anemones, coral, sea pansies, sea fans, and sea pansies, sea fans, and sea whipssea whips
Nearly all contain Nearly all contain symbiotic algae, symbiotic algae, dinoflagellates, in dinoflagellates, in exchange for foodexchange for food
Many of the brilliant Many of the brilliant colors come from the colors come from the algaealgae
Some reproduce Some reproduce asexually by buddingasexually by budding
Others sexual with Others sexual with sperm and egg being sperm and egg being released into the ocean released into the ocean where fertilization where fertilization occursoccurs
Zygotes develop into Zygotes develop into planulae that settle and planulae that settle and develop into polypsdevelop into polyps
Class AnthozoaClass Anthozoa
Class AnthozoaClass Anthozoa Sea anemones- Small and Sea anemones- Small and
colorful in coastal areascolorful in coastal areas– Highly muscular- can retract Highly muscular- can retract
when touchedwhen touched
– Reproduce asexually by Reproduce asexually by splitting themselves into twosplitting themselves into two
CoralsCorals– Colonies called reefsColonies called reefs
– Secrete calcium carbonate Secrete calcium carbonate skeleton that cements to skeleton that cements to skeletons of neighborsskeletons of neighbors
– Top layer is living polypsTop layer is living polyps
– Bottom layers are old skeletonsBottom layers are old skeletons
http://video.google.com/videoplay?docid=2146135098468558056&ei=QPWqSLrmO4OcrwLvmayYAQ&q=cnidarians&vt=lf&hl=en
Great Barrier ReefGreat Barrier Reef
http://ngm.nationalgeographic.com/ngm/0101/feature2/media.html
http://www.aims.gov.au/docs/online-data/reef-from-space.html