1. Phylum Cnidaria (jellyfish, coral and other stingers…)

2. Phylum Cnidaria Class Scyphozoa Class Hydrozoa Class Anthozoa
Jellyfish
Class Hydrozoa
Hydras
Class Anthozoa
Sea Anemones, Coral

3. Phylum Cnidarian
There are about 10,000 species of the phylum Cnidaria, almost all of which are marine. (less than 50 are freshwater)
They represent the next highest level of organization in animals
They possess true tissues
Most radially symmetric
Soft-bodied
Carnivorous animals that have stinging tentacles.

5. Cnidarians…
The name Cnidaria comes from the Greek word "cnidos," which means stinging nettle.
Cnidaria have cnidocytes, stinging cells located on along tentacles.
Each cnidocyte contains a nematocyst, a poison filled structure that has a coiled dart.
Cnidocytes are arranged around their mouths
Casually touching many cnidarians will make it clear how they got their name when their nematocysts eject barbed threads tipped with poison.

6. Discharged Nematocyst

7. Life Stages of Cnidarian
Two different types of life cycles
Polyp is usually sessile
Medusa is motile

8. Two Basic Body Forms of Cnidaria

9. Cnidarians…
They are diploblastic, meaning they develop from two embryonic germ layers, endoderm and ectoderm.
The layer in the middle is a jellylike layer called a mesoglea

11. Feeding Carnivores (predators) Process of feeding Tentacles grab prey
Lion’s mane eats another jelly
Carnivores (predators)
Process of feeding
Tentacles sting prey with nematocysts
Tentacles grab prey
Prey pulled into mouth
Prey stuffed into gastro-vascular cavity (incomplete digestive tract – no anus)
Undigested food back out mouth

13. Response
Cnidarians gather information from their environment using specialized sensory cells
Both polyps and medusas have a nerve net, a loosely organized network of nerve cells.
Other sensory cells include:
: ocelli (for light) and
: statocyst (for gravity)
Cnidarians have nerve nets that consist of many individual nerve cells.

14. Movement Sea anemones have a hydrostatic skeleton.
A hydrostatic skeleton consists of a layer of circular muscles and a layer of longitudinal muscles that, with the water in the gastrovascular cavity, enable the cnidarian to move.

15. Cnidarians… Reproduction
Most cnidarians reproduce both sexually and asexually.
Polyps can reproduce asexually by budding.
In most cnidarians, sexual reproduction takes place with external fertilization. External fertilization takes place outside the female's and male’s body.

17. Ecological Role Predators and prey Neurotoxins in medical research
Coral – jewelry, building, reefs (surfing!)
Coral reefs - habitat for many
-great biodiversity
- protect coastline
Symbiosis with other organisms

18. The Jellyfish: Class Scyphozoa (the “cup animals”)
-Range from tiny to almost 4 meters across
-Some species are extremely venomous- The box jellyfish is the most venomous animal in the world and has killed over people since the 1950s.

19. Class Scyphozoa: True Jellyfish
Fried egg jelly

20. Giant Jelly off Coast of Japan

21. Hydra and their Relatives
-Hydras belong to the class Hydrozoa
-Most hydrozoans are colonies of polyps performing specialized functions (Portuguese Man O’ War)
-Hydra are freshwater hydrozoans that don’t have a medusa stage. They only live as polyps.

22. Class Hydrozoa Portuguese man o’ war
Varadero, Cuba

23. Class Hydrozoa Portuguese man o’ war
Brought up on the beach by wind.
National Geographic -

24. Brown Hydra with Buds

25. Anemones and Corals -This is the class Anthozoa (“flower animal”)
-Corals and anemones only have the polyp stage
-Anemones are solitary polyps
-Corals form colonies of polyps that look like tiny anemones.
-Colonies grow over thousands of years producing calcium carbonate structures that build huge reefs that are threatened.
-Corals form mutualistic relationships with algae.

26. Class Anthozoa
Cabbage Coral

27. Sea Pen

28. Class Cubozoa
The world most venomous animal is the sea wasp (a kind of jellyfish with 60 tentacles, each 15 feet long) that has enough venom to kill 60 adult humans.