Phylum Cnidaria

Do Now Observe the sea anemone and jelly fish. Write down characteristics you see or any you already know of.

Target Goal

Video: Jellyfish Scene from Nemo

Phylum Cnidaria Vocabulary Polyp Medusa Cnidocyte Nematocyst Gastrovascular cavity Extracellular Spawning

Cnidarians - jellyfish, coral, hydra, sea anemone *Named after the stinging cells found on their tentacles called CNIDOCYTES

Cnidarians have two body forms: polyp (vase shaped)               medusa (cup shaped)

Portuguese Man of War - cnidarian that floats in the water and has long tentacles

Coral Reefs are made from the skeletons of cnidarians

General Characteristics Symmetry: Radial First animals with real specialized tissues 3 Body Layers: Ectoderm-outer layer Mesoglea-loose jelly-like layer Endoderm-inner layer Gastrodermis aka Gastrovascular cavity

Specialized Cells: Cnidocytes Stinging cells, found on tentacles Nematocyst Barbed thread within the cell To capture prey or self- defense

What kind of symmetry do cnidarians have? Question Time! What kind of symmetry do cnidarians have?

Name the 3 tissue layers of cnidarians.

The stinging cells on cnidarians are called. a. nematocysts. b The stinging cells on cnidarians are called a. nematocysts b. cnidocytes c. tentacles

2 Body Forms Medusa Polyp Free-flowing Jelly-like Umbrella shaped Polyp Tubelike Attach to an object In both forms there is a fringe of tentacles around the mouth Some Cnidarians exist only in one body form, others alternate between the 2 body forms

Hydra Anatomy WORD BANK Gastrovascular cavity Tentacle Cnidocyte Ectoderm Endoderm Mesoglea Ovary/Teste Bud Nematocyst Mouth Basal Disk

Life Processes Digestion: Begins extracellularly, in the gastrovascular cavity Enzymes break food down into fragments Cells then engulf the fragments Digestion is then completed intracellularly

Life Processes Respiration: Oxygen and Carbon Dioxide are exchanged by diffusion Nervous System: Nerve cells form nerve nets Little coordination is present

Life Processes Support and Locomotion: Water is contained under pressure in the gastrovascular cavity Reproduction: Asexual Fragmentation- sea anemone pull themselves in half Budding-Hydra Sexual External Fertilization Hermaphrodites Spawning

Class Hydrozoans Freshwater: Example-Hydra Only exist as Polyps Stick to rocks or plants with a material they secrete from their basal disc Are able to flip their bodies and move

Class Hydrozoans-use both body forms Marine: Can form colonies but are not interdependent Example-Portuguese man-of-war (Physalia) Float on the surface of the water Their tentacles dangle and can reach 60 m long Used to stun and entangle prey Nematocysts have a powerful neurotoxin that may kill humans Example-Obelia As polyps they may bud Those buds can take a medusa form as a male or female The medusa produces gametes An embryo is created The embryo becomes a larvae called a planula (w/ cilia) That planula settles on the ocean floor and becomes a polyp once again

Class Scyphozoa Referred to as true jellyfish Active predators that ensnare and sting their prey Size range goes from a thimble to a queen sized mattress Can be polyps at some point in their life cycles Examples: Aurelia Has a life cycle like a Obelia One difference is that most of the life cycle for the Aurelia is in the medusa stage

Class Anthozoans Largest classes Exist only as polyps Contain a symbiotic algae Dinoflagellates Cause brilliant colors Reproduce asexually with budding Reproduce sexually by 1. Releasing eggs and sperm into the ocean 2. Fertilization occurs planulae settle and develop into polyps

Class Anthozoans Example: Sea Anemone Soft-bodied polyps Found in coastal areas Feed on fish and other marine life Highly muscular and complex Asexual-pulling apart Example: Coral Live in colonies called reefs Some have soft bodies Many secrete a tough outer skeleton made of calcium carbonate Only the top layer is living When they die their skeleton remains and is a foundation for the new generation Found in tropical regions

Jellyfish relatives: Class Cubozoan Box Jellies, sea wasp A polyp phase in their life cycle has never been observed Most are between 1 cm and 25 cm Live in the tropical northern coast of Australia Phylum Ctenophora Comb Jellies Only have a medusa phase Have no cnidocytes Instead they have a sticky substance that traps plankton Many are small but their tentacles can be 10x the length of their bodies

Videos Long Jellyfish Video http://www.youtube.com/watch?v=9HMLVQipn7s Sea Anemone http://www.youtube.com/watch?v=deDNgChc_7I http://www.youtube.com/watch?v=B1JfZ5kVtE0 Sea Anemone and Jellyfish http://www.schooltube.com/video/d8533c098bd93439f0c5/Cnidarian%20(sea%20an emone%20and%20jelly%20fish) Cnidarian Reproduction and Nematocyst method http://www.youtube.com/watch?v=ct9KyLmnu0I