Darwin's Eye

Structure of the Eyespot and Associated Organelles

2009-01-13T15:42:00.000-08:00

From Journal of Cell Science
Observations on the Fine Structure of the Eyespot and Associated Organelles in the Dinoflagellate Glenodinium Foliaceum
PDF download

The functional and phylogenetic significance of dinoflagellate eyespots
John D. Dodge
Journal: BioSystems, ISSN: 0303-2647, Vol: 16, Issue: 3-4,Date: 1983, Pages: 259-267
Abstract: The eyespots or stigmas from five species of dinoflagellates fall into three distinct categories: independent eyespot which is not membrane bound; independent eyespot which is surrounded by three membranes; eyespot situated at the periphery of a chloroplast. In all cases the eyespot is situated behind the longitudinal groove or sulcus and there is a strand of microtubules between the eyespot and the cell covering or theca. In two cases the strand has been clearly shown to originate near the base of the longitudinal flagellum, which is the one passing over the eyespot and is also responsible for directional movement of the cell. The microtubular strand is presumed to play a part in the transmission of directional stimulation from eyespot to flagellum and a hypothesis is advanced to explain how this may be brought about. Phylogenetically, the structure of the various types of eyespots would link these dinoflagellates with euglenids and chrysophytes, and the diversity found in the dinoflagellates is probably a reflection of the diverse origin of chloroplasts in this group.

Here's a link to a full online article by him in pdf.

DINOFLAGELLATES : INVESTIGATION AND PHYLOGENETIC SPECULATION By JOHN D. DODGE. Botany Department, Royal Holloway College, Egham, Surrey, TW20 0EX, England.

Euglenid and Eye Spot -- Sample #27

2009-01-12T22:57:00.000-08:00

In contrast to many of the other microscope videos I make, once converted to flash, I delete the original file (due to computer space). But I will provide a download link for the original avi in compressed format (as it was captured directly from the microscope slide).

Sea Creature with Light-Sensitive Eyespot (January 5, 2009 #27)
The original compressed avi is provided in the event that somebody may have more advanced digital editing software than those tools at my disposal and to extract the highest quality images. The following media may be downloaded and used for personal and commercial purposes, but please note the source as Sharon Mooney and this blog URL.
salt_water_27.avi (56,963 k) Highly recommended to right-click and "Save Target As".
salt_water_27.flv (5,282 k) flash format.
darwin_eye_003.flv (9,466 k) flash format, modified brightness and contrast (see embedded video below).

Here's the January 5, 2009 #27 clip adjusted for brightness and contrast, in hope to show more definition on the red eye spot:

Plankton sample taken from Atlantic Ocean/Intracoastal Waterway on January 5, 2009.

Sample #26

Sea Creature with Light-Sensitive Eyespot (January 5, 2009 #26)
The original compressed avi is provided in the event that somebody may have more advanced digital editing software than those tools at my disposal and to extract the highest quality images for their own personal use. The following media may be downloaded and used for personal and commercial purposes, but please note the source as Sharon Mooney and this blog URL.
salt_water_26.avi (73,585 k) Highly recommended to right-click and "Save Target As".
salt_water_26.flv (6,904 k) flash format.
darwin_eye_004.flv (15,387 k) flash format, modified brightness and contrast (see embedded video below).

Sample #18 and #20

Sea Creature with Light-Sensitive Eyespot (January 5, 2009 #18 and #20)
The original compressed avi is provided in the event that somebody may have more advanced digital editing software than those tools at my disposal and to extract the highest quality images for their own personal use. The following media may be downloaded and used for personal and commercial purposes, but please note the source as Sharon Mooney and this blog URL.
salt_water_18.avi (51,542 k) Highly recommended to right-click and "Save Target As".
salt_water_18.flv (5,173 k) flash format.
darwin_eye_005.flv (15,387 k) flash format, modified brightness and contrast (see embedded video below).
and clip #20
salt_water_20.avi (23,390 k) Highly recommended to right-click and "Save Target As".
salt_water_20.flv (2,378 k) flash format.

Eye Lens and Refraction in Protozoa

2009-01-12T15:49:00.000-08:00

Edward Babinski wrote,

"I once read about a protozoan species with a lens. A single-celled species with a lens inside that single cell. Weird."

Hans Thewissen wrote,

"Sharon, good to hear from you. I like diatoms and dinoflagellates. Certainly, diatoms are very important in geology, their shells are used to date rocks. Keep up the good work, it is neat to hear you talk about the eyespots and the evolution of the eye. I had not thought that far, being more vertebrate centered."

Glad to know you're still out there. Speaking of "vertebrate centered" -- I just got the information I was looking for (I think) -- big piece of the puzzle.

John Harshman wrote,

"I once read about a protozoan species with a lens. A single-celled species with a lens inside that single cell. Weird."

"He probably meant this:
~ tolweb.org/Dinoflagellates/2445

Go down to where it talks about ocelloids."

Complex Organelles
"Ocelloids: The ocelloid found in warnowiid genera is a complex organelle showing extraordinary resemblances to metazoan eyes, but at a subcellular level. It is entirely comparable to vertebrate eyes. Ocelloid types of different complexity and location in the cell are known (video clip of an ocelloid). Ocelloids consist of three primary components: a lens-like, refractile hyalosome, an ocular chamber, and a darkly pigmented melanosome (Greuet 1978). Microtubules are able to change the shape of the lens, and it appears that it can focus light on the surface of the retinoid (Francis 1967), although how this information is used is unclear."

Complete with photos / video.
Awesome. I'll certainly pass this on and make record of it.

February 1999, National Geographic, Plants with a Touch of Glass

2009-01-10T07:35:00.000-08:00

This comes from the February 1999, National Geographic Magazine, Pgs 114-121, "Diatoms, Plants with a Touch of Glass"

(Pleurosigma is featured on the front cover.)

"Single celled algae, tens of thousands of diatom species, including delicate Pleurosigma, inhabit fresh water or ocean. All build glass shells of fantastic form and practical use."

Article and Photo credits by Darlyne A. Murawski

There's no disputing Charles Darwin on this point: "Few objects are more beautiful than the minute siliceous cases of the diatomacaea, were these created that they might be examined and admired under the higher powers of the microscope?" So Darwin wrote in 1872, sounding as much the Victorian connoisseur as the peerless field scientist. The symmetry and grace of diatoms are now even more evident when seen under the extreme magnification of a scanning electron microscope or in the polarized light of Nomarski interference microscopy, as in the colored images here.

And the living algae that once inhabited these silica shells? About 70,000 species, both fossil and recent have been described and that may only the half of it. As small as they are diverse (some 25 million would fit in a teaspoon), diatoms are both abundant and essential. They make up about a quarter of plant life by weight and produce at least a quarter of the oxygen we breathe. In life they provide high quality nutrition to animals as small as protozoans and as large as baleen whales. In death they rain down on ocean floors, where their oil-rich plasma is eventually buried and transformed into petroleum. Their skeletons are mined for use as filters and abrasives.
Diatoms enable biologists to prinpoint sources of water pollution and monitor the health of ecosystems. They help geologists reconstruct the history of ancient climates. As for me? I stand with Darwin.

The article concludes on this note,

"Optical magic of prisms and polarized light transforms a collection of freshwater diatoms into a bauble factory. Biologist Edward Theriot points out that diatoms have been used as tracers in military intelligence, to connect criminals to crime scenes, to locate the sites of drownings, and in archaeology to find the sources of clay in ancient pots. Almost all diatoms are benign, and that's good. Because they're everywhere."

Light Sensitive Salt Water Micro-Organism (January 5, 2009 #28)

2009-01-09T23:14:00.001-08:00

Here we have phytoplankton sample video clip #28 from January 5, 2009 (Atlantic Ocean/Intracoastal Waterway).

Download link for the original avi in compressed format (as it was captured directly from the microscope slide).
Sea Creature with Light-Sensitive Eyespot (January 5, 2009 #27)
The original compressed avi is provided in the event that somebody may have more advanced digital editing software than those tools at my disposal and to extract the highest quality images. The following media may be downloaded and used for personal and commercial purposes, but please note the source as Sharon Mooney and this blog URL.
salt_water_28.avi (27,809 k) Highly recommended to right-click and "Save Target As".
salt_water_28.flv (2,571 k) flash format.
darwin_eye_002.flv (5,877 k) flash format, modified brightness and contrast (see embedded video below).

January 5, 2009 #28 clip adjusted for brightness and contrast, in hope to show more definition on the red eye spot:

Plankton sample taken from Atlantic Ocean/Intracoastal Waterway on January 5, 2009.

Darwin's Eye

2009-01-09T17:14:00.000-08:00

In contrast to many of the other microscope videos I make, once converted to flash, I delete the original file (due to computer space). But I will provide a download link for the original avi in compressed format (as it was captured directly from the microscope slide).

Sea Creature with Light-Sensitive Eyespot (January 5, 2009 #29)
The original compressed avi is provided in the event that somebody may have more advanced digital editing software than those tools at my disposal and to extract the highest quality images. The following media may be downloaded and used for personal and commercial purposes, but please note the source as Sharon Mooney and this blog URL.
salt_water_29.avi (56,963 k) Highly recommended to right-click and "Save Target As".
salt_water_29.flv (5,282 k) flash format.
darwin_eye_001.flv (12,466 k) flash format, modified brightness and contrast (see embedded video below).

Here's the January 5, 2009 #29 clip adjusted for brightness and contrast, in hope to show more definition on the red eye spot:

Plankton sample taken from Atlantic Ocean/Intracoastal Waterway on January 5, 2009.

This critter (I presume to be a protozoan of some sort), was an important luck encounter. It is the third species of water organism I've seen and had the opportunity to make video and photography from. Which enters the argument for Darwin's theory relating to the "evolution of the eye". Whether or not Darwin's theory of natural selection is right or wrong is not the case, these creatures may be the basis for the argument, and my only interest is to obtain and provide stock photography for them. Numerous extracted photos for public educational use... the yellow disk that is setting nearby is the diatom, Coscinodiscus, a concentric diatom from the Atlantic Ocean for which I regularly make videos and photography.

Frame 00;00;01;10

Frame 00;00;01;11

Frame 00;00;01;12

Frame 00;00;01;13

Frame 00;00;01;14

Red Eyespot on Euglena

2009-01-09T15:22:00.000-08:00

Larger image (Magnified above at 40x)

Another freshwater critter of curiosity I caught dancing around among the algae. Though its green like algae, it moves about on its own. A noticeable feature, was the bright reddish spot...

Originally posted as Freshwater Micro-Organism

Sharon wrote: I noticed on your page you have a very similar phytoplankton to the one I found.

But it is not the same species. I want to identify the species. Mine has a red dot on it, which looks like an eye, but I do not believe it is in an eye.

Please can you help me to identify this species?

Thank you, Sharon Mooney

------------

It's almost certainly a euglenoid.

IF it was flexible in motion (e.g., the cell body itself flexible, not just the flagella), it is almost certainly a member of the genus Euglena.

The red spot is in fact an 'eyespot' - it's a very primitive eye that allows the euglena to detect light -- a big advantage for a mobile photosynthesizer.

Dr. Rochelle Sturtevant
Extension Educator
NOAA
Great Lakes Sea Grant Network
Great Lakes Environmental Research Lab

Heres the same magnified by combination of microscope and camera

Large Image

Large Image

Large Image

Large Image

Photos and Video of Euglena, Page One
Photos of Euglena, Page Two
Euglena Images, Page Three

Euglena Images, Page Four