Class Hydrozoa Polyps are small and may occur as solitary or colonial

A.Body plan B.Colony Growth C.Life History

Polyps are small and may occur as solitary or colonial

Colonies grow in one of 3 main patterns

Hydrorhizal

Monopodial

Sympodial Colony Growth Forms

Medusae are small and not as structurally Characteristics of Class Hydrozoa complex as the scyphozoan medusae (Polyp and Medusa are prominent in some species)

1 Siphonophores: Composed of clonally produced multicellular zooids

Polymorphism within colonies of Hydrozoa Highest division of labor & most precise organization

bio.fsu.edu/.../images/Female-Hydractinia.jpg

Velella velella (by-the-wind-sailor) Characteristics of the Anthozoa (Sessile, inactive lifestyle)

ClassAnthozoa

A. Diversity

B. Body plan

C. Cloning

D. Symmetry

E. Life History

Diversity of Class Anthozoa • Hexacorallia SubClass Hexacoralia Actinaria (anemones) Order Actinarea

Scleractinea (corals)

• Octocorallia

Alcyonacea (soft corals)

Gorgonacae (sea fans etc.)

2 Anthozoan Polyp Symmetry in Cnidaria compared to other animals What morphological characteristics associated with a larger polyp size?

Nemanostella

Anthopleura elegantissima Clonal reproduction in anemones

Internal or external budding § The Aggregating Anemone Pedal laceration Fission Tentacular brooding § Clonal wars § Competition for space, § Self-nonself recognition § Research shows individuals have specialized roles

•Ayre, David, and R. K. Grosberg, 2005 Animal Behavior 70: 97-110. •Francis, L, 1976 Biological Bullentin 150: 361-376.

§ Acrorhagi (non-feeding tentacles) Division of Labor Inflates, contacts , nematocyst fire and stick; scarring § Most acrorhagi wins

§ Scout § Warrior § Reproducer § Reserve § Free edge

• If attacked, a warrior often retaliates • If significant injury, retreat by pedal locomotion • Multiple attackers at once can cause extensive injury and death

3 Anemone Line Diversity of Class Anthozoa

SubClass Hexacoralia § As a result of the clone Order Scleractinea war, an anemone free zone is established. § Two separate colonies can co-exist, separated by only a few Stony Corals centimeters.

Class Anthozoa: Class Anthozoa: SubClass Octocorallia SubClass Octocoralia

soft corals Soft corals

StoloniferanSoft Corals corals

Class Anthozoa: Sea Pens Life cycle of Anthozoans Consists of a SubClass Octocoralia Sea Pansies planula that settles to become a juvenile Sea Fans Less complex.

Is this the Ancestral Life Cycle?

Which came first Polyp or medusa?

4 Two Scenarios for the evolution Generalized life cycle of Cnidarians Of the Cnidarian Classes In what way are life cycles altered in Hydrozoa, Scyphozoa, Anthozoa and Cubozoa?

18s r-DNA, mt DNA, & new morphological studies support idea that the Anthozoa is the basal group

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

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