CnidariansThe guys with the stinging tentacles

CnidariansFinally, we see a pie that can be sliced!

Cnidarians actually exhibit radial symmetry in which similar body parts can be grouped around a central axis.

Here we also observe a large jump on the evolutionary scale: tissues that perform specific functions.

Phylum CnidariaThe Classes of Cnidaria are:Anthozoa- Sea Anemones and CoralsHydrozoa- HydraScyphozoa- true jellyfishCubozoa- box-shaped jellyfishCtenophora- non stinging Cnidarians:Comb Jellies**There are over 10,000 species of Cnidarians

All About Cnidarians

Interesting Stuff 1. Jellyfish fact: Jellyfish have been around for more than 650 million years which means that they outdate the dinosaurs and the sharks. 2. Jellyfish fact: Different species of jellyfish can be found in all the worlds oceans. Jellyfish can even be found in freshwater. 3. Jellyfish fact: A species of jellyfish, the Box jellyfish (sea wasp) kills more people than any other marine creature. 4. Jellyfish fact: The worlds largest known jellyfish can reach a diameter of 2.5 m/ 8ft and their tentacles can grow to be half the length of a football field. 5. Jellyfish fact: Jellyfishes uses jet propulsion to make their way through to oceans of the world. Some swim while others mostly drifts with the currents. 6. Jellyfish fact: Some species of jellyfish contain a lot of protein and are thought to be able to play a large role in ending hunger and malnutrition. 7. Jellyfish fact: Jellyfish is able to reproduce both sexually and asexually during different parts of their lifecycles 8. Jellyfish fact: what enables them to survive is their stinging tentacles that protect them from being preyed upon.

Characteristics of CnidariansTwo cell layers (epidermis, gastrodermis, separated by jelly-like layer called mesoglea)Stinging tentaclesSac-like digestive systemRadial symmetryTentacles are arranged in a circle around the mouthNerve net- simple nervous systeminvertebrate

Radial SymmetryCompass jellyfishRadial

AnatomyA. Polymorphism- Cnidarians have more than one body form:1. Polyp2. Medusa

Polyp FormTube with tentacles around the mouthSessileCoral polyp

Polyp (sea anemone)

Polyp (Hydra)

Medusa Umbrella shapeTentacles around mouthMotile, Free-swimming

Cnidocytes-Stinging CellsWithin the cnidocyte is the nematocyst (which is like a capsule)The capsule has the stinging structure which is a hollow thread (Filament) with barbsMost contain a toxinVery small, but discharged in large numbersUsually the sting is only strong enough to kill zooplankton or tiny fishBut there are exceptions!

Discharged nematocysts, stinging cells used for defense and prey capture, have been the plague of more than fish. Stings from certain jellyfish have resulted in death in a matter of hours, especially for infants.

HabitatAquatic:Most are MarineA few are freshwater

Two Tissue Layers1. EPIDERMIS OUTER LAYER2. GASTRODERMIS STOMACH CAVITYMESOGLEA JELLY MATERIAL BETWEEN TISSUE LAYERS ABUNDANT IN JELLYFISH TO HELP THEM FLOAT

One Opening SystemFood enters through the mouth and is digested in thee cells.Wastes are excreted through the mouth.WASTES, GAMETES OUTSperm and eggs are released through the mouth.FOOD IN

Feeding1. Carnivores (predators)2. Process of feedinga. Tentacles sting prey with nematocysts b. Tentacles grab prey c. Prey pulled into mouth3. Prey moved into gastro-vascular cavity (GVC)*4. GVC makes enzymes, breaks down food, extra-cellular digestion5. Undigested food moves back out of mouth

Lions mane eats another jelly!

Process of feeding

3. Prey stuffed into gastro-vascular cavity (GVC)*4. GVC makes enzymes, extra-cellular digestion5. Undigested food back out mouth*incomplete digestive tract (no anus)

Lions mane jellyfish eating

RespirationVia diffusion Body is two cell layers thick

ResponseNo nervous systemNo brainNerve net around mouthNerves cover the body but do not tell the difference between body parts.

LocomotionMedusa- motile, free-swimmingPolyps- sessile, attached to hard substrateExceptions: 1. Hydra tumbles on tentacles 2. Sea anemones glide on pedal disc

Reproduction

1. Asexual budding2. Sexuala. Medusae release sperm & eggs b. Larvae are free-swimming

Life Cycle of a Typical CnidarianAlternation of GenerationsOne form is the polyp (a cylinder with the closed end attached to the substrate and the open end with the mouth and tentacles directed upward)The other form is the medusa, free-swimming, with the mouth underneath (like a jellyfish)

Life Cycle of a Typical CnidarianAlternation of Generationsasexual

Ecological RolePredators and preyNeurotoxins in medical researchCoral jewelry, building, reefs (surfing!)Coral reefs - habitat for many different species, great biodiversity, protect coastlineE. Symbiosis with other organisms

Do Now

Explain how the jellyfish is adapted for floating?How do jellyfish capture and digest their prey?Describe how a typical jellyfish reproduces.How does the adult form of a jellyfish differ from that of a sea anemone?How does a sea anemone obtain its food?How does the sea anemone respond to stimuli?

Class Anthozoa: Sea Anemones

Class Anthozoa: Corals

FORMATION OF CORAL REEFSCORAL REEFS ARE BUILT BY MILLIONS OF CORAL POLYPS OVER THOUSANDS OF YEARSEACH POLYP CREATES A CUP OF CALCIUM CARBONATE TO LIVE INCORALS REPRODUCE ASEXUALLY BY BUDDING, THIS PROCESS HELPS COLONIES TO GROWOLD SKELETONSPOLYPS ARE CONNECTED

FORMATION OF CORAL REEFSCORALS ALSO REPRODUCE SEXUALLY ONCE A YEAR BY RELEASING SEX CELLS INTO THE WATER.THIS HELPS TOP ESTABLISH NEW COLONIES

HARD CORALSREEF BUILDERS USE CALCIUM FOR SKELETONEACH SPECIES HAS A UNIQUE COLONY & CUP DESIGNEXAMPLES: BRAIN, ELKHORN, STAR

Class Scyphozoa: True JellyfishFried egg jelly

Giant Jelly off Coast of Japan

Remember you can only touch the tops!!!

Jellyfish Humor

Portuguese Man 0 War(a Hydrozoan), NOT a true jelly fish

Portuguese Man 0 WarTentacles of Physalia physalis

Chironex fleckerithe Box jelly fish

Irukandji syndrome:

A sting from this little guy can cause the following:

It begins with a mild sting, followed by severe lower back pain, muscle cramps in arms, legs, stomach and chest. It causes sweating,anxiety, nausea, vomiting, headaches and palpitations, and has alsobeen known to cause cardiac failure.

Carukia barnesi: the badest of the bad!

Portuguese Man o War vs. Box Jelly fish

COMB JELLIESPHYLUM CTENOPHORACTEN REFERS TO FUSED PLATES OF CILIA LOOK LIKE A COMB STRUCTUREDO NOT CONTAIN STINGING CELLSUSE CILIA TO FILTER WATERBASIC CHARACTERISTICS:TENTACLES ARE STICKY TO CATCH FOOD

Comb jellies: Ctenophora

Similar to cnidarians in most respects.

Nearly 100 species.

Contain cilliary combs which assist in prey capture and mobility.

***************************Hann!!!***********