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 layerMesoglea-loose jelly-like layerEndoderm-inner layer

Gastrodermis akaGastrovascular cavity

Specialized Cells:Cnidocytes

• Stinging cells, found on tentacles

• Nematocyst • Barbed

thread within the cell

• To capture prey or self-defense

Question Time!WHAT KIND OF SYMMETRY DO CNIDARIANS HAVE?

Name the 3 tissue layers of cnidarians.

The stinging cells on cnidarians are called

a. nematocystsb. cnidocytesc. tentacles

2 Body Forms Medusa

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 TentacleCnidocyteEctodermEndodermMesogleaOvary/TesteBudNematocystMouthBasal Disk

Life Processes

Digestion:Begins extracellularly, in the gastrovascular cavity

Enzymes break food down into fragments

Cells then engulf the fragmentsDigestion 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:

AsexualFragmentation- sea anemone pull

themselves in half Budding-Hydra

SexualExternal Fertilization

HermaphroditesSpawning

Class Hydrozoans

Freshwater:Example-Hydra

Only exist as PolypsStick to rocks or plants with a material they

secrete from their basal discAre 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 longUsed to stun and entangle preyNematocysts have a powerful neurotoxin that may kill humans

Example-ObeliaAs polyps they may budThose buds can take a medusa form as a male or femaleThe medusa produces gametes An embryo is createdThe 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%20anemone%20and%20jelly%20fish)

Cnidarian Reproduction and Nematocyst method

http://www.youtube.com/watch?v=ct9KyLmnu0I