Cnidarian Dissection
Moon Jellyfish
• 1 minute video of moon jellyfish “in motion”
• Moon Jellyfish – YouTube
Oral arms vs. marginal tentacles
• A jellyfish has many tentacles. Some hang
around the bell of the jellyfish. These hold the
stinging cells. Other tentacles hang around the
mouth. These are called oral arms. They may
or may not have stinging cells. The oral arms
pass the food into the jellyfish’s mouth. The
food then goes into the animal’s stomach.
Rhopalium
• Rhopalia (singular rhopalium) are the most
obvious sensory structures of scyphozoan
jellyfish. They include specialized structures
for sensing light (eyespots) and movement or
direction with respect to gravity (statoliths).
Moon Jelly
Moon Jelly
Structures to identify
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Bell
epidermis
Oral arms
Tentacles
Mouth
Gastrovascular cavity
Rhopalium
Mesoglea
gonads
Dissection video
• http://www.youtube.com/watch?v=IdhBRz2Yq
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Tentacle observation
• Use a dissecting microscope
Sea anemone
Metridium information
• http://www.boydski.com/diving/photos/metri
dium.htm
Metridium video
• http://www.youtube.com/watch?v=AlNGccPE
NGw
• 1. Metridium fields
• http://www.montereyscubaboard.com/metrid
iumfields.php
Sea anemone
• Feeding:
• http://www.youtube.com/watch?v=nI8A61uq
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Sea anemone: Metridium
Sea anemone dissection
• External: basal (pedal)disk, tentacles, mouth
• Internal: siphonoglyph, pharynx, septa
(incomplete and complete), coelenteron,
acontia, rector muscle, gonads
Lab procedure
• You will have step by step details for
dissection
• Questions/sketches will be completed in your
journal and collected for a grade
• Dissection quiz
– Anatomical directions
– Species information
– Anatomy as seen in dissection