MARINE SCIENCE PHYLUM CNIDARIA

What are Cnidarians?

Soft-bodied animals with stinging tentacles Ex: Jellyfish, anemones, corals, hydras Over 9,000 species

MORPHOLOGY Who thinks they know what type of symmetry most cnidarians exhibit?

THAT’S RIGHT RADIAL SYMMETRY!!!!!!

Body forms:  Medusa, What Shape is this structure?  Polyp, What Shape is this structure?  Single opening surrounded by tentacles Is both mouth and anus Simple Nervous system  No brain

INTERNAL STRUCTURE :  Epidermis  Mesoglea (Jelly-like material in between layers)  Gastrodermis Which layer is the inner layer? Gastrovascular cavity: internal space where digestion takes place

HOW DO YOU THINK CNIDARIANS PROTECT THEMSELVES? FIST FIGHT, WEAPONS, TOXINS, FIGHT OR FLIGHT?

DEFENSE Nematocysts: Stinging structures located on tentacles Spring loaded poison-filled darts  Captures and paralyzes prey  Defense Jellyfish sting! **Not all tentacles have nematocysts; some used for reproduction, feeding

WE KNOW THAT PORIFERA REPRODUCED MULTIPLE WAYS, HOW ABOUT CNIDARIA, HOW DO YOU THINK THEY REPRODUCE?

REPRODUCTION Most Cnidarian life- cycles involve an alteration of generations: two different body forms dominant and conspicuous medusa form smaller polyp form, often restricted to the larval stage. Jellyfish reproduce sexually, and individuals are either male or female. The reproductive organs (gonads) develop in the lining of the gut.

QUICK GUESS HOW MANY CLASSES OF CNIDARIANS DO YOU THINK THERE IS???

CLASSES OF CNIDARIANS: There are four classes of Phylum Cnidaria: 1) Class Hydrozoa– “water animals” 2) Class Scyphozoa– “cup animals” 3) Class Anthozoa– “flower animals” 4) Class Cubozoa– “cube animals”

CLASS HYDROZOA “WATER-ANIMALS” Can have polyp, medusa or both shapes; often have alternation of generations Mostly colonial* Some live in fresh water Ex: Portuguese Man-O-War, Hydras *live in colonies

CLASS SCYPHOZOA “CUP-ANIMALS” True Jellyfish Adult stages have medusa shaped bodies Tentacles can be over 30 m long in some species!!  Some can cause painful stings

CLASS ANTHOZOA “FLOWER-ANIMALS” Sea anemones and corals (hard and soft) Only polyp-shaped bodies Usually sessile Coral polyps secrete a calcium carbonate skeleton for protection  Symbionts with photosynthetic algae

CLASS CUBOZOA Cubozoans are the box jellies. They have a cubical shape when viewed from above Their tentacles are evenly spaced This is the smallest class in terms of species Some box jellies contain deadly toxins in their nematocysts

TREATMENT OF STINGS First: Carefully remove the tentacles. As long as tentacles remain on the skin, they will continue to discharge venom. Second: Apply meat tenderizer, vinegar, tobacco or sodium bicarbonate If stung by a box jelly, seek medical attention immediately! An antivenom is available to prevent mortality. Don’t rub the sting site! Don’t use: Alcohol or human urine. These actually stimulate stinging cells and may increase pain and cause severe skin reactions.

NEXT ACTIVITY NEW GROUPS: GROUP 1: WHITNEY, KEVIN, ERIN GROUP 2: KELSEY, NOELLE, CONNOR GROUP 3: JUSTIN, VICTORIA, SAVANNAH GROUP 4: EMILY, SAY-SAY, KAYLA GROUP 5: KIRBY, JESSICA, MORGAN P GROUP 6: CORINA, JUAN, MORGAN G GROUP 7: OBED, SHAYLA, DEREK, ANTOINETTE