1. Phylum Cnidaria (ny DEHR ee a)
The Highlights of Jellyfish and Hydra life

2. Examples of Cnidarian
Jellyfish
Hydra
Coral
Sea Anemone

3. Cnidarians (ny DEHR ee unz) and Characteristics
Invertebrates
Stinging Cells
Have a central body cavity
Radial symmetry – more than one line of symmetry & parts arranged in a circle

4. BODY STUCTURE:
Polyp: vase-shaped body plan (like a sea anemone, coral or hydra)
Medusa: Bowl-shaped body plan (like a jellyfish)

5. Polyp Mouth opens at the top of its body Tentacles surround the mouth
Attach themselves to an underwater surface

6. More on Medusa Adapted to a life of swimming
Mouths open downward (at the bottom) and is surrounded by tentacles that dangle

7. Life Cycle Some Cnidarians have both body plans in their life cycle…
Sexual
Asexual
(budding)

8. Obtaining FOOD!!! Same way for polyps and medusa
Use their stinging cells to catch prey
Some have sharp spines with venom
Venom paralyzes them – pull prey into their mouths with tentacles
Prey goes into hollow central body cavity to be digested
Waste goes out of mouth.

9. Movement Many Cnidarians can move to escape Jellyfish swim
Hydra turn slow somersaults
Sea Anemones bend from side to side, stretch out, shrink down or move slowly
Nerve net – nerve cells arranged like a basketball net – help with this movement

10. Life in a Colony
Some species of Cnidarians spend life in a colony – a group of many individual animals
Examples: Coral and Portuguese man-of-war

11. Coral Reefs Found in warm shallow water Built by cnidarians
A coral polyp attaches to a solid surface (broken shell, sunken ship, rock or reef ball)
Polyp produces a hard, stony skeleton around its soft body
Home to more species of fishes and invertebrates than any other environment on Earth

12. Coral Reefs in Danger More than 1.5 million recreational divers
Divers can cause damage by standing on or even touching fragile reefs
Collecting coral for jewelry or decoration (now illegal)…should they ban diving all together?
Oil spills, tropical storms, changes in sea level and temperature, and illegal fishing can also harm reefs

13. Portuguese Man-of-War

14. Portuguese Man-of-War
Contains as many as 1,000 individuals that function together as one unit
Top of medusa is a gas-filled chamber that allows the colony to float
Various polyps with different functions drift below by the tentacles
Some polyps catch prey and others digest the prey…some are adapted for reproduction