Presentation on theme: "INTRO TO CNIDARIA FISH310 Spring 2015"— Presentation transcript:
1 INTRO TO CNIDARIA FISH310 Spring 2015 Cnidaria= greek for a stinging thread.FISH310Spring 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 larvaOnly 2 tissue layers of tissue (epidermis and gastrodermis) with mesoglea in-betweenA single opening to the digestive systemTentacles around the mouthExclusively aquatic, mostly marineCnidea (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=mouthaboral=non-mouth sideOnly 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 cnidoblastsCnidea 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.
12 Class: Hydrozoa ~3,000 mostly marine species Typically small, with polyp and medusa stageMembers include:HydroidaSiphonophoraHydrocorallinaGastrodermis lacks cnideaNo cells in mesogleaHydroida= generally medusoid as adults. Free medusae (colonial jellies) or marine attached hydroidsSiphonophora= portuguese man o’ warHydrocorallina= 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. 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 guideNote colony form, polymorphism, life history
15 Class: Anthozoa ~7,500 species Lack a medusa stage Some species have algal symbiontsMembers IncludeCoralsanemonesSea pensAnthozoa= flower animalsAnemonesNo medusa stage, just polyp.
17 See a cool movie on Anemones Anthozoan Evolution!
18 Anthozoa – In labToday we will look at the external and internal anatomy of a sea anemoneDissection:Metridium senile.Body planAcontiaLive speciemensAnthopleura elegantissimaAlgal symbiontsAcrorhagi
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 nematocystsExtend outside body through small pores in body wallFunction 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.AcrorhagiHollow spherical protrusions covered with potent nematocytsFunction in defending territoryToday we will see these defensive structures in our Anthopleura dissections
21 Algal SymbiontsCheck out the algal symbionts in our local anemone: Anthopleura elegantissimaBenefit for host and algae?Zoochlorellae- single celled green algaeZooxanthellae – dinoflagellate of the genus Symbiodinium
23 Scyphozoan Sensory Structures Sensory organs include:Statocysts – balance organOcelli – light receptorStatocysts and ocelli are contained within structures called rhopaliaCubozoans 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 Mount1. 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 power2. 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 readingsDiscussion board postsgroup projectThursday:Steven Roberts SAFS seminarDNA methylation in marine invertebrates4pm
28 CLEAN UP Thoroughly wash all dissection tools and trays Dispose of animal remains in biohazard container in the fume hoodRinse slides & toss coverslips in sharps containerMake sure your scopes are clean and turned offPresent your worksheet