1 / 31

INTRO TO CNIDARIA

INTRO TO CNIDARIA. FISH310 Spring 2015. Defining Characteristics. Cnidea ( nematocysts ) Radial symmetry (mostly!) Planula larvae - free-swimming, flattened, ciliated, bilaterally symmetric larva Only 2 tissue layers of tissue (epidermis and gastrodermis) with mesoglea in-between

hlasalle
Télécharger la présentation

INTRO TO CNIDARIA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. INTRO TO CNIDARIA FISH310 Spring 2015

  2. Defining Characteristics • Cnidea (nematocysts) • Radial symmetry (mostly!) • Planula larvae - free-swimming, flattened, ciliated, bilaterally symmetric larva • Only 2 tissue layers of tissue (epidermis and gastrodermis) with mesoglea in-between • A single opening to the digestive system • Tentacles around the mouth • Exclusively aquatic, mostly marine

  3. Polyp or Medusa body plans with an oral-aboral axis

  4. Cnidea (nettle/stinging thread) • Multiple Functions: • food collection, defense and locomotion. • Can be specialized for wrapping around small objects, sticking to surfaces, penetrating surfaces, or secreting proteinaceous toxins. • Cells that contain cnidea are called cnidoblasts

  5. Nematocysts! Nematocyst animation! Nematocysts firing under a microscope!

  6. Discharge triggered by chemical/physical stimulation of modified cilia (cnidocil). Takes only 3 ms! • Primary force behind expulsion is osmotic pressure, although the exact mechanism remains uncertain. Different types of cnidea may operate by different mechanisms.

  7. Major classes of Cnidaria • Hydrozoa • Hydra • Portuguese man o' war • Anthozoa • sea anemones • Corals • sea pens • Scyphozoa • jellyfish • Cubozoa • Box jellies

  8. Phylogenetic tree • Main diveragence is between the Anthozoa and Medusozoa • Major lineages diveraged over half a billion years ago.

  9. http://biorxiv.org/content/early/2015/04/06/017632

  10. Class: Hydrozoa • ~3,000 mostly marine species • Typically small, with polyp and medusa stage • Members include: • Hydroida • Siphonophora • Hydrocorallina • Gastrodermis lacks cnidea • No cells in mesoglea

  11. Portuguese Man O’War: not a “true” jellyfish http://video.nationalgeographic.com/video/manowar_portuguese

  12. Hydrozoans – In lab • Examine colonial polyp • Identify species using field guide • Note colony form, polymorphism, life history

  13. Class: Anthozoa • ~7,500 species • Lack a medusa stage • Some species have algal symbionts • Members Include • Corals • anemones • Sea pens

  14. Coral Reefs

  15. See a cool movie on Anemones Anthozoan Evolution!

  16. Anthozoa – In lab • Today we will look at the external and internal anatomy of a sea anemone • Dissection: • Metridium senile. • Body plan • Acontia • Live speciemens • Anthopleura elegantissima • Algal symbionts • Acrorhagi

  17. Acontia Let’s look at the acontia of our local Metridium spp. • Thin filaments extending from the middle lobe of the mesenteries loaded with nematocysts • Extend outside body through small pores in body wall • Function in offense, defense, & digestion

  18. Sea Anemones at War! Acrorhagi • Hollow spherical protrusions covered with potent nematocyts • Function in defending territory Today we will see these defensive structures in our Anthopleura dissections

  19. Algal Symbionts Check out the algal symbionts in our local anemone: Anthopleura elegantissima Zoochlorellae- single celled green algae Zooxanthellae – dinoflagellate of the genus Symbiodinium

  20. Class:Scyphozoa • ~ 200 species • True jellyfish • Mainly medusoid

  21. Scyphozoan Sensory Structures Sensory organs include: • Statocysts – balance organ • Ocelli – light receptor Statocysts and ocelli are contained within structures called rhopalia Cubozoans also have highly advanced sensory structures (lensed eyes)

  22. Life cycle of Aurelia aurita (moon jellyfish) • A Mature female medusa (30 cm in diameter) carrying planula larvae (red arrow) in brood pouches in the oral arms. • B released, free-swimming planulae (0.2-0.3 mm). • C Polyp (1-3mm). • D Beginning strobilation. • E Advanced strobilation. • F Young Ephyra (3-5mm). • G Ephyra, 4 weeks after release (8-10mm). The Moon Jelly Life Cycle

  23. Making a Wet Mount • 1. Gather a thin slice/piece of whatever your specimen is. If your specimen is too thick, the coverslip will wobble on top of the sample like a see-saw and you will not be able to view it under high power • 2. Place ONE drop of water directly over the specimen. If you put too much water, the coverslip will float on top of the water, making it hard to draw the specimen (Plus too much water is messy) • 3. Place the coverslip at a 45 degree angle with one edge touching the water drop and then gently let go. Performed correctly the coverslip will perfectly fall over the specimen. Try to avoid air bubbles.

  24. Next lab: Resilience project • Assigned readings • Discussion board posts • group project • Thursday: • Steven Roberts SAFS seminar • DNA methylation in marine invertebrates • 4pm

  25. Lab review

  26. CLEAN UP • Thoroughly wash all dissection tools and trays • Dispose of animal remains in biohazard container in the fume hood • Rinse slides & toss coverslips in sharps container • Make sure your scopes are clean and turned off • Present your worksheet

  27. Unused

  28. Feeding Anemone Feeding Video Anemone Feeding on Jellyfish Hydra Feeding Video Jellyfish Feeding

  29. LET’S FIRE SOME!

More Related