Subject: Re: Plant awareness/Animal Photosynthesis

From: [email-masked]
Date: Sun, 23 Nov 1997 10:26:52 -0500 (EST)

In a message dated 11/22/97 2:24:17 PM, you wrote:

>While animals may not directly photosynthesize to the extent of plants,
>corals, clams and other reef invertebrates do harbor algae in their
>tissue which, through photosynthesis, share nutrients with their host.
>This fairly recent discovery explains why such a nutrient desert as
>coral reefs can support such a huge and diverse biomass.
>					Gordon Watkins

Algae, being plants, conduct the photosynthesis.  Saying that these are
examples of animal photosynthesis is like saying fungi conduct photosynthesis
because they form symbiotic associations with algae as lichens.  

(Algae is a deceptively simple term, describing two (at least) vastly
different groups of plants, one a eucaryotic photosynthetic bacterium, often
called cyanobacteria, and the other a more mordern plant with nucleus and
other cellular structures, such as chlorella.  It is interesting but not
surprising that as the ancient originators of photosynthesis, at least by
pathways that have survived the rigors of three or four billion years, these
plants have developed many symbiotic associations with species as equally
remote as fungi and mollusks.  Evolution goes any direction that works.
 Thus, though through Darwinian influences on our concept of biology, we may
be very familiar with divergent development, e.g. speciation from a
progenitor species into variations on a theme, there is well supported
thought that evolution also represents convergence of species, in which
symbiosis becomes so intrinsic that the component species have no practical
measure of separation.  The chloroplast in the vascular plants may be such an
example, possibly having cyanobacteria ancestors that entered symbi here
without the development of the flowring plants in particularly, important.)

I was not thinking of being a host of symbioitic photosynthesis when I
suggested that animals to a small degree photosynthesize.  We can come closer
to home than, say mollusks, for example.  When irridated with sunlight, human
skin normally photosynthesizes vitamin D from the dread substance,
chlorestol.  While rather obligatory in its dependence on chemically more
fundamental photosynthesis of glucose from water and carbon dioxide, this is
a truely valid example of animal photosynthesis.  

Animal photosynthesis via chlorophyl would indeed be an elegant further
convergence, as we could recycle our wastes back into food by standing in the
light.  However the need to move about would be greatly diminished and we
might need to find other ways to procreate and otherwise dance as our
motility diminished.  I'll stick with vitamin D for this lifetime, I think,
and bop around as is both necessary and delightful.

For Mother Earth, Dan Hemenway, Yankee Permaculture Publications (since
1982), Elfin Permaculture workshops, lectures, Permaculture Design Courses,
consulting and permaculture designs (since 1981), and now correspondence cours
es via email.  One is now underway.  Next Live program:  Paraguay, 9/98.
Internships available. Copyright, 1997, Dan & Cynthia Hemenway, P.O. Box 52,
Sparr FL 32192 USA  [email-masked]  

We don't have time to rush.