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Phylum Cnidaria

Date post: 21-Jan-2016
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Phylum Cnidaria. Jellyfish, hydra, sea anemones, & coral. Cnidarian questions. What do we already know about Cnidarians (from the phlyo. Tree) Two tissue layers (germ layers)(ecto and endoderm) “diploblastic” Radial Symmetry 2. Look at the life cycle of a jellyfish… - PowerPoint PPT Presentation
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Jellyfish, hydra, sea anemones & cora
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Page 1: Phylum Cnidaria

Jellyfish, hydra, sea anemones, & coral

Page 2: Phylum Cnidaria

Cnidarian questions1. What do we already know about

Cnidarians (from the phlyo. Tree)1. Two tissue layers (germ layers)(ecto and

endoderm)1. “diploblastic”

2. Radial Symmetry2. Look at the life cycle of a jellyfish…

A. What are the two body types of Cnidarians?B. Which is mobile? Sessile?

A. Medusa is mobileB. Polyp is sessile

Page 3: Phylum Cnidaria

AppearancePolyp: cylindrical, vase shaped animals that are usually attached to a rock or sea floor

Ex. Hydras, sea anemones, corals

Medusa: bell-shaped body; umbrella

Ex. Jellyfish

Page 4: Phylum Cnidaria

Appearance (cont.)

Page 5: Phylum Cnidaria

SymmetryRadial symmetry

Page 6: Phylum Cnidaria

Skeletal/Muscle SystemNO MESODERM, so…no real muscles!

most have primitive muscle cells coral have external skeleton of calcium

carbonate

Page 7: Phylum Cnidaria

Capturing Prey LET’S EAT!!!cnidarians are

carnivores (eat meat) use tentacles

arranged in a ring around their mouth to capture prey

when a “trigger” is stimulated on a stinging cell called the cnidocyte, a harpoon or nematocyst shoots out & injects poison into the prey

Cnidocyte (stinging cell)

Nematocyst (harpoon)

Page 8: Phylum Cnidaria

Capturing Prey: Cnidocyte and Nematocyst at work

Cnidocyte (stinging cell)

Nematocyst (harpoon)

Page 9: Phylum Cnidaria
Page 10: Phylum Cnidaria

DigestionSac w/ a digestive cavity (gastrovascular

cavity) w/ a single opening that acts as a mouth/anus

Jellyfish Hydra

Page 11: Phylum Cnidaria

Digestion (cont.)food is pushed into the gastrovascular cavity

where digestion begins (extracellular digestion)

undigested remains leave through the mouth/anus

Page 12: Phylum Cnidaria

Nervous SystemNo brain or even ganglia, no

cephalization, etcNerve Net- have simple sensory receptors

that detect & respond to stimuli

Page 13: Phylum Cnidaria

CirculationNONE!!

Page 14: Phylum Cnidaria

RespirationDiffusion- oxygen from water moves into

cells (high to low)

Page 15: Phylum Cnidaria

Reproduction Asexual – budding- formation of

outgrowths that pinch off from parent to live independently

Sexual- forms a zygote and free swimming form that settles on ocean floor (usually a polyp)

*MOST ALTERNATE B/W POLP & MESDUSA LIFE FORM

Page 16: Phylum Cnidaria

Reproduction (cont.)

Page 17: Phylum Cnidaria

Reproduction (cont.)

Page 18: Phylum Cnidaria

ExcretionDiffusion to release waste

Page 19: Phylum Cnidaria
Page 20: Phylum Cnidaria

Class Hydrozoa • Ex- Hydra•both asexual polyps and sexual medusa stages•Spends most of its life in the polyp stage

Reproduction: •Sexual: eggs and sperm are shed into the water and form fertilized eggs; planula is by passed with eggs hatching into young hydras •Asexual reproduction via budding

Page 21: Phylum Cnidaria

Class Hydrozoa cont.

Other Hydrozoans

Portuguese man-of-war: Single gas-filled float with tentacles Tentacles house the polyps and modified medusae of the colony

Page 22: Phylum Cnidaria

Class Scyphozoa

Jellyfish• The medusae are large and contain massive amounts of mesoglea•Sexual and Asexual reproduction

Page 23: Phylum Cnidaria

Class Anthozoa

•include sea anemones and coral

•Exclusively marine; there is no medusa stage

• Most anthozoans are colonial (e.g. corals) and secrete external skeletons composed of calcium carbonate.

Page 24: Phylum Cnidaria

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