Photographs: structure of Millepora platyphylla skeleton

The Tabulae are apparent in the following photographs of Millepora platyphylla Skeletons

 

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I was attracted to the study of Millepora platyphylla because of their hard parts, their skeleta.  My overriding interest was in reproductive timing.  The Milleporid  Hydrozoan corals had me from where I learned that their reproductive status is heralded by certain characters in their hard parts, the ampullae, which are exhibited only when they are reproductively active: the ampulla is a protective cove in the skeleton that houses the medusae, the reproductive individual that carries forth the gametes.  I reasoned that information regarding seasonality of reproduction could be learned by studying time series of their the hard parts.  

I have to admit that I have learned little about the hard parts of Millepora.  Much more could be learned.  

 

Recently I have been awakened to a seriously interesting aspect of the biology of Millepora spp.: the degradation of the tissues, and the zooxanthellae, especially in the lower layer of the living tissue.   This, in turn, has turned my attention to another aspect of the morphology of their skeleta:  as the tissues lay down more and more layers of the Calcium Carbonate---the skeletal tissue---the polyps produce a sequence of new basement plates.  Akin to the sequence of corallites in scleractinian corals, these plates leave behind a sequence of consecutive chambers, evidence of the progressive accretion of the massive skeletal structure, the corallum. 

These plates are termed the tabulae.  Interestingly, tabulae are also described for the extinct rugose corals, in the _Treatise on Invertebrate Paleontology_.  

 

I note, in part:

• The distance between successive tabulae varies.  One wonders to what extent growth rate of the corallum is determined by, or alternatively determines, the gaps between deposition of these tabulae.  
• The surface of the colony is planar.
• Structure is organized at several levels: (1) gross morphology (tabulae and apparent palisades forming a corallite wall-figure 5);  (2) orthogonal crystalline (trabulae?)--figure 3; and over the broken surface may be seen grains, as in figure 1 and others.
• thick bands orthogonal to the tabulae are visible 

 

Photographs

The following photographs are presented.  It is planned to continue to capture other views of the hard parts of Millepora spp.

 

1

2

3

4

5

Much remains to be learned from studies of the skeletal remains of Millepora platyphylla.

These images were made with a Canon EOS M50, with the 28mm EF-M macro lens.  This is the maximum magnification with this lens, without additional add-on supplementary lenses.  This lens does not accept an extension tube.