Phylum CnidariaPages 307-311

CNIDARIANS-“STINGING CELLS”

• SEA JELLIES• SEA

ANEMONES• CORALS• HYDRA

Just the facts…

• CARNIVORES• STINGING CELLS CALLED NEMATOCYSTS

• HOLLOW CENTRAL CAVITY

Body Characteristics• Body Symmetry: Radial• Cell Organization: Cells form into

muscle-like tissues, no organs or organ systems

• Reproduction: Sexual and Asexual• Body Development: Zygote to Larva to

Polyp to Adult

Cnidarian Anatomy

POLYP• SHAPED LIKE A

VASE• MOUTH OPENING

AT TOP(ONE OPENING)

• MOST DO NOT MOVE AROUND (sessile)

HYDRA

Cnidarian Anatomy

MEDUSA

• BOWL-SHAPED• FREE SWIMMING• MOUTHS OPEN

DOWNWARD

SEA JELLY

HOW CNIDARIANS FEED• CAPTURES PREY

USING STINGING CELLS CALLED NEMATOCYSTS

• TENTACLES PULL FOOD INTO ITS MOUTH.

• FOOD IS DIGESTED IN ITS CENTRAL CAVITY AND EXPELLED THROUGH ITS MOUTH

The Lion's Mane Jelly is a venomous

SEA JELLY which can sting people

with its long tentacles

CNIDARIAN REPRODUCTION

SEXUAL• SOME CARRY BOTH

SPERM AND EGG.• SOME ARE EITHER

MALE OR FEMALE

ASEXUAL• BUDDING• SPLITS INTO TWO

Throughout its life, the Sea Jelly is found in both a polyp and a medusa form.

Sea Jellies

• Sea jellies are invading!

CORAL

• A coral colony consists of hundreds or thousands of tiny polyps. Each polyp is an individual animal (basically a small anemone) but they live together as a group.

Coral Reefs• Reefs are made

when coral attaches itself to the ocean floor.

• When it dies its hard skeleton is left behind.

• The skeletons build up and form large masses.Australia's Great Barrier Reef

SEA ANEMONE

• These flower-like animals

resemble plants, but they have a mouth

at the center of their tentacles, and a primitive

digestive system

The Tealia anemone.

Hydra • 3-8mm in length• Live in fresh water• Live in both body

structures throughout their life– Polyp– Medusa

• Mouth surrounded by tentacles

• If disturbed, a barbed thread and poison is ejected from the nematocyst

Hydra reproduce by budding