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

• Bell• epidermis• Oral arms• Tentacles• Mouth• Gastrovascular cavity• Rhopalium• Mesoglea• gonads

Dissection video

• http://www.youtube.com/watch?v=IdhBRz2Yq1Q

Tentacle observation

• Use a dissecting microscope

Sea anemone

Metridium information

• http://www.boydski.com/diving/photos/metridium.htm

Metridium video

• http://www.youtube.com/watch?v=AlNGccPENGw

• 1. Metridium fields • http://www.montereyscubaboard.com/metridiumfields.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