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Presentation on theme: "INTRO TO CNIDARIA FISH310 Spring 2015"— Presentation transcript:

Cnidaria= greek for a stinging thread. FISH310 Spring 2015

2 sea anemones in arctic circle, Portuguese man o war, solitary hydrozoan, orange sea pen, box jelly, nomura’s jelly (7-8ft in diameter)

3 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 Cnidea (or nematocysts) All radial symmetry except (exception?) sea pen. Planula larva-heavily cilicated microscopic sausage

4 Polyp or Medusa body plans with an oral-aboral axis
oral=mouth aboral=non-mouth side Only one hole/single opening to digestive system.

5 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 Cnidea unique to members of this phylum.

6 Nematocysts! Nematocyst animation!
Nematocysts firing under a microscope!

7 Discharge is triggered by a combination of chemical and tactile stimulation
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.


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

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


12 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 Hydroida= generally medusoid as adults. Free medusae (colonial jellies) or marine attached hydroids Siphonophora= portuguese man o’ war Hydrocorallina= Pink or purple hydrocoral, colonial and secrete a substantial calcareous skeleton.

13 Portuguese Man O’War: not a “true” jellyfish
The Portuguese man o' war is composed of four types of polyps.[4] One of the polyps, a gas-filled bladder called the pneumatophore . The other three polyp types are known as dactylozooid (defence), gonozooid (reproduction), and gastrozooid (feeding).[

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

15 Class: Anthozoa ~7,500 species Lack a medusa stage
Some species have algal symbionts Members Include Corals anemones Sea pens Anthozoa= flower animals Anemones No medusa stage, just polyp.

16 Coral Reefs

17 See a cool movie on Anemones
Anthozoan Evolution!

18 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

19 Acontia Let’s look at the acontia of our local Metridium spp.
Near the base of anthozoans, thin filaments called acontia extend from some species. Loaded with nematocysts and secretory cells and can be extended outside the body through small pores in the body wall. Used both offensively and defensively, may also function in digestion. 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

20 Sea Anemones at War! Acrorhagi
Acrorhagi- small spherical bulges extending around circumference of body column below tentacles. Can be extended a substantial distance from body column. Used in defending a territory against invasion by other anemones. Acrorhagi Hollow spherical protrusions covered with potent nematocyts Function in defending territory Today we will see these defensive structures in our Anthopleura dissections

21 Algal Symbionts Check out the algal symbionts in our local anemone: Anthopleura elegantissima Benefit for host and algae? Zoochlorellae- single celled green algae Zooxanthellae – dinoflagellate of the genus Symbiodinium

22 Class: Scyphozoa ~ 200 species True jellyfish Mainly medusoid

23 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)

24 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 ( mm). C Polyp (1-3mm). D Beginning strobilation. E Advanced strobilation. F Young Ephyra (3-5mm). G Ephyra, 4 weeks after release (8-10mm). Strobilation= form of asexual reproduction consisting of the spontaneous transverse segmentation of the body. Ephyra= immature jellies. The Moon Jelly Life Cycle

25 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. Question 6- will examine cnidea in dissected anemone. Can add small amount of acetic acid to fire them.

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

27 Lab review

28 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

29 Unused

30 Feeding Anemone Feeding Video Anemone Feeding on Jellyfish
Hydra Feeding Video Jellyfish Feeding


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