1 / 27

Hydrozoa: Colony Growth and Life History

Learn about the diverse growth forms and life cycles of the Hydrozoa class, including the unique characteristics of polyps and medusas. Discover the evolutionary adaptations and polymorphism within colonies of Hydrozoans.

elkinsk
Download Presentation

Hydrozoa: Colony Growth and Life History

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

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

  3. 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.

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

  5. Obelia hydroid has prominent medusa and polyp

  6. 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

  7. 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

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

  9. Siphonophores: Composed of clonally produced multicellular zooids Highest division of labor & most precise organization 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!.

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

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

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

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

  14. Symmetry in Cnidaria compared to other animals Nemanostella

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

  16. 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: 97-110. • Francis, L, 1976 Biological Bullentin 150: 361-376.

  17. Division of Labor • Scout • Warrior • Reproducer • Reserve • Free edge

  18. 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

  19. 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.

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

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

  22. Class Anthozoa: SubClass Octocoralia Soft corals

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

  24. 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?

  25. 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

  26. 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

More Related