1. Class Hydrozoa Body plan Colony Growth Life History
Polyps are small and may occur
as solitary or colonial

3. Colonies grow in one of 3 main patterns
Hydrorhizal
Monopodial
Sympodial
Colony Growth Forms

4. True or False? Support your answer.
A jellyfish has no eyes or nose and no brain or heart! They do not even have a head. Their body is almost totally made of water and is soft having no bones at all. Jellyfish are invertebrate animals because they do not have a spine or backbone.
jellyfish - NOAA Ocean Explorer
oceanexplorer.noaa.gov/forfun/creatures/02_jellyfish/main.html
True or False? Support your answer.

5. Characteristics of Moon jelly
(Polyp and Medusa are prominent in some species)

6. Obelia hydroid has prominent medusa and polyp

7. Gonionemus Hydractinea Planula larva Obelia Hydra
Hydrozoan have evolved a variety of life cycles that include reduction of polyp in Gonionemus, loss of medusa in Hydractinea, and direct development in Hydra
Gonionemus
Hydractinea
Planula
larva
Obelia
Hydra

8. Immortal Jellyfish Turritopsis nutricula,
the immortal jellyfish, is a hydrozoan whose medusa form can revert to the polyp stage after becoming sexually mature.
Involves Stem cells
and
Trans-differentiation
of cells
Transdifferentiation one differentiated cell type transforms into another
Theoretically, this process can go on indefinitely, effectively rendering the jellyfish biologically immortal,[3][5] although, in nature, most Turritopsis are likely to succumb to predation or disease in the medusa stage, without reverting to the polyp form

9. Polymorphism within colonies of Hydrozoa consists of 4 different polyps: feeding, reproductive, stinging, and defensive (spine)
bio.fsu.edu/.../images/Female-Hydractinia.jpg

10. Siphonophores: Composed of clonally produced multicellular zooids
Highest division of labor & most precise organization
ll the zooids in a given siphonophore colony are descended from a single fertilized egg. The egg develops into the protozooid, a polyp that gives rise through budding to all the other zooids of the colony.
All the zooids in a given siphonophore colony are descended from a single fertilized egg. The egg develops into the protozooid, a polyp that gives rise through budding to all the other zooids of the colony, including the float!.

11. Velella velella (by-the-wind-sailor)
Gonozooids, gastrozooids, dactylozooids and the pneutamophore are Zooids are derived from individual polyps.

12. Characteristics of the Anthozoa (Sessile, inactive lifestyle)
ClassAnthozoa
Diversity
Body plan
Cloning
Symmetry
Life History

13. Hexacorallia
Actinaria (anemones)
Scleractinea (corals)
Octocorallia
Alcyonacea
(soft corals)
Gorgonacae
(sea fans etc.)

14. Anthozoan Polyp
What morphological characteristics associated with a larger polyp size?

15. Symmetry in Cnidaria compared to other animals
Nemanostella

16. Clonal reproduction in anemones
Internal or external budding
Pedal laceration
Fission
Tentacular brooding

17. Anthopleura elegantissima
The Aggregating Anemone
Clonal wars
Competition for space,
Self-nonself recognition
Research shows individuals have specialized roles
Ayre, David, and R. K. Grosberg, 2005 Animal Behavior 70:
Francis, L, 1976 Biological Bullentin 150:

18. Division of Labor
Scout
Warrior
Reproducer
Reserve
Free edge

19. Acrorhagi (non-feeding tentacles)
Inflates, contacts , nematocyst fire and stick; scarring
Most acrorhagi wins
If attacked, a warrior often retaliates
If significant injury, retreat by pedal locomotion
Multiple attackers at once can cause extensive injury and death

20. Anemone Line
As a result of the clone war, an anemone free zone is established.
Two separate colonies can co-exist, separated by only a few centimeters.

21. Diversity of Class Anthozoa
SubClass Hexacoralia
Order Scleractinea
Stony Corals

22. Class Anthozoa:
SubClass Octocorallia
soft corals
Soft Corals
Stoloniferan corals

23. Class Anthozoa:
SubClass Octocoralia
Soft corals

24. Class Anthozoa:
SubClass Octocoralia
Sea Pens
Sea Pansies
Sea Fans

25. Life cycle of Anthozoans Consists of a planula that settles to become a juvenile
Less complex.
Is this the
Ancestral
Life Cycle?
Which came first
Polyp or medusa?

26. Two Scenarios for the evolution
Of the Cnidarian Classes
18s r-DNA, mt DNA, & new morphological studies support idea that the Anthozoa is the basal group

27. Generalized life cycle of Cnidarians
In what way are life cycles altered in the 4 classes?
Ancestral Anthozoa: polyp adult only; sexual and asexual
Hydrozoa: medusa stage evolved; becomes sexual adult
Scyphozoa: medusa stage dominant; polyp small, asexual
Cubozoa: loss of polyp stage