Eyespots in protists

Carol Dieckmann dieckman at email.arizona.edu
Thu Jan 16 18:24:24 EST 2003

Dear Chlamy community,

I received the following email from a writer interested in eyespots.  I
was able to answer many of his questions and provide references from the
literature, but some of you may know more, especially about different

Carol Dieckmann

         steve winter <ye_river_xiv at yahoo.com>

Hi folks,

I know you don't know me or anything, but I've been
looking for some information about eyespots on the
web, and it seems Arizona's the only show in town...
I didn't expect this to be so hard to find, maybe I'm
just not looking in the right places.

Anyway, I'm not a scientist, or researcher of any
kind, I'm just trying to write a fictional book, about
a fictional protozoa, and I wanted a few basic
questions answered.  If you don't know, or don't want
to tell me for some reason, I can understand, but
hopefully you can at least point me to a good book
about it or something.

So here's a basic description of my fictional
protozoa, and then I'll list some questions...

The protozoa is encased in a tubular cell wall,
composed mainly of magnesium calcites.  The ends of
the tubes are tesselated, somewhat like the top of a

Inside the cell are the common organelles,
chloroplats, mitchondria, endoplasmic reticulum,
ribosomes, lysosomes, etc.  The nucleus is divided
into micronucleus, and macronucleus.  There is at
least one eyespot, various strains have slightly
different eyespots.  There is also a magnetite
crystal, much like the ones purported to exist on the
so called "martian nanofossils" of ALH48001.  A wreath
of pseudo pods extend out of each end of the tubular
cell wall, with a Flagellum extending from amoingst
them on one end, and an organelle capable of producing
electricity protruding from the other end in the
middle of the pseudopods.

This protozoa is a bit smaller than the average


1. What is the "average" size of protozoa, and what
sort of proportions to the body length would the
flagellum, eyespots, etc be?

2. I have heard that some protozoans have eyespots in
their chloroplasts, while others have them separate,
usually attached to the flagellum in some way.  Do any
have both?  what are the average sizes of each?  how
do those with the eye spots in the chloroplasts know
where the light is?

3.  How does an eyespot detect light?  what is it's
shape? can it detect the direction the light comes
from, the color?  what is the average size of an
eyespot?  What wavelenghts, or range of wavelenghts of
light does an eyespot detect?  are different eyespots
able to detect different wavelenght ranges of light?
what are the limits of visible light for the protozoan

I have other questions, but I suppose these are the
ones you're most likely to know, as others deal with
non-protozoan details.  Thanks for any information you
can provide me with,


Steven A. wintergerst


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