No symmetry, no HOX genes, no true tissue, sequential hermaphorditism (changes sex)
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What is a choanocyte?
a beating flagella to pull water in for filter feeding
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Examples of cnidaria
jelly fish, sea anemones, corals
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Describe the process of gastrulation
single-layered blastula transformed into double-layered gastrula
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2 body forms of cnidaria
polyp & medusa
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What is the gastodermis?
The inner cavity of a polyp and medusa
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How do cnidaria move?
Medusa use jet propulsion - coronal muscle relaxes, subumbrelar cavity expands and fills with water, then coronal muscles contracts, forcing water jet from cavity
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Describe the nerve net in polyps
consists of sensort, motor, and interneurons. Dual nerve net connected by interneurones - allows multi-directional impulses
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Describe the nerve net in medusae
Same as polyps but with additional nerve rings, ganglia function as a "pacemaker" for swimming muscles
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What is a Chironex fleckeri?
sea wasp (jelly fish)
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What is a Physalia physalis?
Portuguese man o' war (jelly fish)
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What are the 4 classes of cnidaria?
Hydrozoa, Scyphozoa, Cubozoa, Anthozoa
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Characteristics of hydrozoa
Mostly marine, both polyp and medusa stage, polyp stage often colonial
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