(urth) Today, a Sea Slug. Tomorrow, ... ?

Jerry Friedman jerry_friedman at yahoo.com
Sun Jan 17 20:14:16 PST 2010

--- On Sun, 1/17/10, Jeff Wilson <jwilson at io.com> wrote:
> > Severian's friend the Green Man
> always seemed quite plausible to me. I
> > hadn't realized just how plausible. Apparently a sea
> slug has
> > incorporate algae genes into its genome and produces
> and uses
> > chlorophyll inside its body:
> >
> > http://www.sciencenews.org/view/generic/id/53496/title/Sea_slug_steals_genes_for_greens,_makes_chlorophyll_like_a_plan

That's pretty amazing, if it's confirmed.
> There's still a question of him being able to intercept
> enough sunlight to
> be more active than a slug. A man-sized silhouette in
> Earthly conditions
> intercepts less than 100 calories worth of sunlight a day.

Is that with perfect efficiency?  Gosh, are you seriously
telling me to do the calculation?  Half a square meter in
sunbathing position, 1 kilowatt, 8 hours, that's 14,400
kJ or about 3400 big calories.  You're assuming something
like present photosynthetic efficiency.

> From the Green
> Man's sunny smile, his people apparently still have
> humanlike teeth, so
> presumably they can eat a variety of food to make up the
> deficit, but I'm
> not sure if reducing your food needs by 1/30 is worth the
> hassle.

The sun could be brighter in his time than ours, and genetic
engineering could have improved the efficiency of
photosynthesis and that of metabolism.

> It might be that the chlorophyll isn't strictly for food,
> but for sensory
> purposes; can anyone think of an occasion when the Green
> Man would need to
> be able to feel a shadow falling on him, or would have to
> distinguish
> between bright lights of different character?

I can't  We do fine with vision.  Though human color
vision is rather klugy, I gather, and those same
genetic engineers could probably improve it without
any cost by making it more like birds'.

Jerry Friedman


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