Lecture 3 The Northern Star poculata by John R. Finnerty

Astrangia is a Scleractinian coral. are anthozoan cnidarians. Cnidarian Phylogeny

Trachyline Other Cubozoa Scyphozoa hydrozoa hydras hydrozoa

- -

+ MEDUSOZOA

(Bridge et al. 1997)

Anthozoan Phylogeny HEXACORALLIA ~4,300 (hard corals) (6 fold symmetry) Corallimorpharia (mushroom corals) Antipatharia (black corals) Actinaria (sea anemones) Zoanthidea (zoanthids) Ceriantharia (tube anemones) Alcyonaria (soft corals) Pennatulacea (sea pens)

OCTOCORALLIA Helioporacea () ~3,000 species (8 fold symmetry) Scleractinian Corals Secrete a calcium carbonate skeleton “Hermatypic” corals, which typically live in shallow tropical waters, harbor symbiotic algae called zooxanthellae inside their endodermal cells. These can supply ~90% of the corals organic carbon. Corals can also feed on using their tentacles or capture bacteria or dissolved organic matter on layer of surface mucus which is then moved to the mouth using cilia.

Scleractinia Anatomy of a A of dinoflagellates that is the predominant photosynthetic intracellular symbiont in cnidarians. Also found in sponges, flatworms and giant clams. Receive inorganic nutrients from the host (carbon dioxide, ammonium). Return organic compounds, primarily carbohydrates to the host. This is a mutualistic relationship (a symbiotic relationship where both participants experience a fitness benefit)

Bleaching Under stressful conditions, corals will actively expel their zooxanthellae, a phenomenon called bleaching. Hermatypic corals cannot survive indefinitely in the bleached state. Why is interesting?

It can survive for prolonged periods in zooxanthellate/ symbotic or azooxanthellate/ aposymbiotic states. It has an extremely large latitudinal range (Caribbean to Nova Scotia). It is extremely cold- tolerant.

Madracis ROBUSTA Stenocyathus caryophylliids Pocilloporidae Pocillopora damicornis Madrepora caryophylliids siderastreids siderastreids + Leptastrea Fungiidae Plocoida faviinids + meandriinids Astrangia Montastrea faveolata caryophylliids Anthemiphylliidae Pseudosiderastrea Thalamophyllia Galaxea COMPLEXA Agariciidae Astreopora Alveopora Acropora digitifera Acropora, Anacropora, Acropora millepora Guynia Acropora palmata Stephanocoenia Bathycola Siderastrea Porites asteroides Porites, Goniopora, Poritipora, Stylaraea Porites compressa Dendrophylliidae