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Defending the Christian Worldview, Creationism, and Intelligent Design

This is my personal virtual library, where i collect information, which leads in my view to the Christian faith, creationism, and Intelligent Design as the best explanation of the origin of the physical Universe, life, and biodiversity

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Defending the Christian Worldview, Creationism, and Intelligent Design » The catalog of life » Spectacular Convergence: A Camera Eye in a Microbe

Spectacular Convergence: A Camera Eye in a Microbe

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Spectacular Convergence: A Camera Eye in a Microbe

Erythropsidinium ocelloid dinoflagellates

The little fellow I am gonna describe now has the most extraordinary and unbelievable eyes known, similar to camera eyes of vertebrates, and occupies one-third of its body weight. A science paper described its eyes as " the most elaborate photoreceptor organelle known in a unicellular organism ". Furthermore, it can point its eyes to different directions, and as such, is far more sophisticated than simple eyespots in Euglena. Its eyes can spot and detect polarised light, which helps even more to detect its prey. It contains lenses that function to concentrate light, AND - it doesn’t have a brain—or even a nervous system—but, nonetheless, it can see. Scientists have yet to fully understand how this single-celled organism might create an image of something without a brain.

It has a flagellum, which is described as " a piston, a fast contractile appendage unknown in any other organism, which is responsible for locomotion through successive extensions and contractions, and so, its speed is faster than any other dinoflagellates. Furthermore, the end of the piston possesses a "suction cup" able to attach the prey and place it into the posterior cavity for engulfing. It hunts by shooting out darts with stings. It has a sensory mechanism and can perceive when prey comes close.

Ladies and gentlemen - its name is Erythropsidinium Spectacular Convergence: A Camera Eye in a Microbe 1f632Spectacular Convergence: A Camera Eye in a Microbe 1f603Spectacular Convergence: A Camera Eye in a Microbe 1f60eSpectacular Convergence: A Camera Eye in a Microbe 1f60d
Applause to its creator - Jahwe - Jeshua - holy Ghost - triune God, inventor extraordinaire Spectacular Convergence: A Camera Eye in a Microbe 1f609Spectacular Convergence: A Camera Eye in a Microbe 1f609Spectacular Convergence: A Camera Eye in a Microbe 1f642Spectacular Convergence: A Camera Eye in a Microbe 1f642

Eye-like ocelloids are built from different endosymbiotically acquired components 1

Multicellularity is often considered a prerequisite for morphological complexity, as seen in the camera-type eyes found in several groups of animals. A notable exception exists in single-celled eukaryotes called dinoflagellates, some of which have an eye-like ‘ocelloid’ consisting of subcellular analogs to a cornea, lens, iris, and retina.

Ocelloids consist of subcellular components resembling a lens, a cornea, iris-like rings, and a pigmented cup called the retinal body, which together so resemble the camera-type eyes of some animals that they have been speculated to be homologous. 

The ocelloid is among the most complex subcellular structures known, but its function and evolutionary relationship to other organelles remain unclear.

Spectacular Convergence: A Camera Eye in a Microbe Cb7nqsx

The “retina” of this eye, a curved array of chromosomes, appears arranged to filter polarized light. The news item from the Canadian Institute for Advanced Research quotes Brian Leander, co-supervisor of the project:
“The internal organization of the retinal body is reminiscent of the polarizing filters on the lenses of cameras and sunglasses,” Leander says. “Hundreds of closely packed membranes lined up in parallel.”

Spectacular Convergence: A Camera Eye in a Microbe DmVvJfj
Seeing the Master Designer Through a Microbe’s Eye...

Inside a single-celled organism called a warnowiid is a sophisticated structure that looks just like an eye—an ocelloid. Ocelloids look so eye-like that, when they were first discovered in the warnowiid family of plankton, some thought they were eyes of jellyfish the plankton had eaten! Scientists led by University of British Columbia’s Brian Leander have found out what ocelloids are really made of. They believe their discoveries shed light on warnowiid evolution and the evolution of eyes.
The ocelloid is “an amazingly complex structure for a single-celled organism to have evolved,” says lead author Greg Gavelis. “It contains a collection of sub-cellular organelles that look very much like the lens, cornea, iris and retina of multicellular eyes found in humans and other larger animals. [] No comparable assemblage resembling a camera eye has ever been found inside any other unicellular organism. While many have eyespots—dots of photoreceptor pigment that capture light and enable a cell to orient itself in response to the light’s direction and intensity—the ocelloid is unique.

Warnowiids are a family of dinoflagellates—a group of protozoans named for their whirling whip-like flagella. The many warnowiid species all have ocelloids. One even has ocelloids with multiple lenses. Warnowiids also exhibit other complex features. Some fire tiny harpoons analogous to the stinging harpoons jellyfish use to capture their dinner. Some have ballistic “pistons,” their function yet unknown. [Michael Le Page, “This Single-Celled Bug Has the World’s Most Extraordinary Eye,” New Scientist, June 16, 2015,] Some warnowiids can produce their own food through photosynthesis like plants do, but most species cannot.Because some warnowiids contain bits of other dinoflagellates, scientists suspect they consume their cousins. However, because warnowiids die when removed from their natural habitat, it is hard to study their behavior. Therefore, scientists have not yet seen exactly how they use their pistons and ocelloids. [Nature (Gavelis et al. “Eye-Like Ocelloids . . . ” doi:10.1038/nature14593) and from an additional study led by its senior author Dr. Brian Leander (Hoppenrath et al., “Molecular Phylogeny . . . ” doi:10.1186/1471-2148/9/116).]

So is the ocelloid a product of random evolution or a masterful design? Scientists cannot answer this question through direct observations. [] As evolutionists try to explain how a structure like this ocelloid evolved, they naturally look at its components and how they are assembled. Therefore, if a scientist is convinced that all life forms that exist must have evolved, then it appears obvious that evolution built the ocelloid from these organelles. [] The ocelloid story seems to them like a dramatic scenario, millions of years old, reenacting evolutionary steps practically before their eyes.

But the issue of irreducible complexity presents a problem for the evolutionists. Without instructions, the differentiation and assembly of multiple parts into a complex whole cannot plausibly happen. All the parts of a multicomponent structure like this would need to be in place for the ocelloid to work, yet each is a specialized form of an already complex structure. What evolutionary advantage could accrue to a proto-warnowiid from the evolution of the ocelloid’s separate parts? After all, in its chloroplast-like component the thylakoid membranes are configured the wrong way for an ordinary chloroplast. The apparent irreducible complexity of the ocelloid is more consistent with a biblical “God-created” worldview than with an evolutionary one.

The planktonic dinoflagellate Erythropsidinium possesses an ocelloid and piston. It is not necessary an ocelloid or an eye just only to detect light. More simple organelles with pigments, i.e., eyespots, are able to differentiate between light and darkness. The question is whether a unicellular organism, is able to see or at least to differentiate shadows.
A unicellular organism cannot see, I mean to interpret an image as humans and other vertebrates. In order to see, you need two organs: a brain and at least one eye, the second eye is useful to calculate distances. The eye is only translating the light signal, and the brain to interpret the image. The eye and the brain are multicellular structures, and in consequence unicellular organisms cannot see because they have not eyes or brain. However, Erythropsidinium possesses the most elaborate photoreceptor organelle among the unicellular organisms. A cut of the organelle reveals a structure analogous to the eye. It has the retina-like, melanosome, and hyalosome, like the liquid inside our eyes, and the lens-like. The lens of Erythropsidinium concentrates the light on the retina as in our eyes. However, the ocelloid of Erythropsidinium probably cannot project on the retina a real image. The reason is that the ocelloid of Erythropsidinium lacks a convergent lens. Even, if it is able to project a real image, there is not brain or nervous system to interpret the image. Erythropsidinium concentrates the light in its photoreceptor, retina, and when an object, a potential prey or predator, creates interference, the ocelloid of Erythropsidinium could register the position, the transparency and size. That is all the information that Erythropsidinium needs to know. I mean to find a suitable prey and to escape from potential predators.

While other unicellular organisms of the marine plankton are moving continuously, Erythropsidinium stays quiet, apparently observing around, even moving the ocelloid in different directions, and when disturbed it escapes moving vigorously the piston. No other organism in nature has a piston. Both organelles, the ocelloid and the piston, give a competitive advantage.
Erythropsidinium and other relatives with an ocelloid are found in the euphotic zone, illuminate layer, of the ocean, Gómez 2008, Eur. J. Protistology 44, 291-298. Obviously, they have a competitive advantage when light is available. It is widespread in the open ocean, but with low abundance usually less than 10 cells per liter. The transparency of the open ocean waters favors the visual predators with an ocelloid. However, even if Erythropsidinium is an efficient predator, the density of potential preys in the open ocean is low and it cannot reach high abundances. Coastal waters are more productive, higher density of potential preys. However, the turbidity reduces the transparency and visual predators are less competitive.

 Studies based on transmission electron microscopy by Greuet in the late 1960´s revealed that the ocelloid of Erythropsidinium consist of a cornea-like surface layer, a lens-like structure, a retina-like structure with stacked membranes, and a pigment cup, all assembled in a single cell. Based on these observations, Gehring 2005, J. Hered. 96: 171-184, proposed a hypothesis for the origin of the eyes. He stated that because dinoflagellates are symbionts in corals, and other cnidarians, dinoflagellates, i.e. Symbiodinium, might have transferred the genes required for photoreception to the cnidarians, and further to other animal groups. However, this feature is not very common in the nature. Certainly, the probability of gene transfer would increase in organisms living in symbiosis. For example, if Erythropsidinium or their relatives could live in symbiosis with animals, we will have more reasons to consider the hypothesis of the gene transfer. Gómez et al. 2009, J. Eukaryotic Microbiol. 56, 440-445, provided the first gene sequence of Erythropsidinium. None of the close phylogenetic relatives of Erythropsidinium lives in symbiosis with animals. However, the results revealed that Erythropsidinium belongs to a group with photosynthetic dinoflagellates with chloroplasts of different origins. Greuet observed that the ocelloid looked like a chloroplast during its formation. We can interpret that Erythropsidinium is able to transform a chloroplast into an elaborate photoreceptor organelle. Although we cannot consider that Erythropsidinium has an eye. This evidences that eye-like structures converge into the same morphology and the complex photoreceptors have different origins in the evolution.


Last edited by Otangelo on Fri Dec 18, 2020 2:56 pm; edited 1 time in total



This single-celled bug has the world's most extraordinary eye

Erythropsidinium is perhaps the most extraordinary eye in the living world – so extraordinary that no one believed the biologist who first described it more than a century ago. It belongs to a group of single-celled planktonic organisms known as dinoflagellates. They can swim using a tail, or flagellum, and many possess chloroplasts, allowing them to get their food by photosynthesis just as plants do. Others hunt by shooting out stinging darts similar to the nematocysts of jellyfish. They sense vibrations when prey comes near, but they often have to fire off several darts before they manage to hit it. It can point its ocelloid in different directions. Erythropsidinium preys on transparent creatures – including other dinoflagellates – that are almost invisible in normal light. But the massive nucleus of dinoflagellates has an unusual property – it just happens to polarise light. So the ocelloid can detect polarised light, making the dinoflagellates that Erythropsidinium preys on stand out clearly against the background.

At the front of the ocelloid is a clear sphere rather like an eyeball. At the back is a dark, hemispherical structure where light is detected. The ocelloid is strikingly reminiscent of the camera-like eyes of vertebrates It has an eyespot with a lens and a light-sensitive pigment,  an eye-like ‘ocelloid’ consisting of subcellular analogues to a cornea, lens, iris, and retina. They have a structure so complex that it was initially mistaken for a multicellular eye. 

They also have ocelloid eyes which are subcellular structures and have all the components we associate with camera-like eyes in vertebrates like us, and in cephalopods like squid and octopus. These complex organelles are light-sensitive, and contain rhodopsins that are associated with vision in all the eyes we know of.

cornea — the clear outer layer of the eye which gathers light
iris — rings which limit light like the diaphragm shutter of a camera
lens — which focuses incoming light
retina — which receives the focused light and generates a chemical image signal.

My comment: The human eye consists of over two million working parts making it second only to the brain in complexity. That rises the question: How can unguided evolutionary forces give rise the phenotypic structures, that are convergent and similar, where one requires 2 million working parts, employed in multicellular organisms, and the other is unicellular? That seems far better explained by the action of a common designer.  

The evolutionary storytelling:
Consider that a camera-like eye with a cornea, lens, and retina has evolved independently in the following diverse groups of organisms:

- single-celled Warnowiid dinoflagellates
- box jellyfish
- cephalopods (squid, octopus, cuttlefish)
- vertebrates (from lamprey to fish to mammals)

Perhaps the evidence is showing us that the camera-like eye is not a particularly difficult visual structure to evolve. Maybe our eyes are not so special. They may even be primitive, basal structures, not very different from eyes in our early vertebrate ancestors, and not so highly evolved. We don’t know the details of how the eye evolved, only that it has done so on many occasions during evolutionary time.

My comment: Claiming that the camera-like eye is not a particularly difficult visual system is far stretching, in face of the complexity of the human eye. Even further, claiming that camera-like eyes may have evolved as many as 40 times during metazoan development is a claim that only blind believers in evolution accept to swallow.  5

The Awesomest Thing in Biology
So says a blogger by the name of Psi Wavefunction regarding an eye-like structure of some protists called the ocelloid. She wrote this in a now defunct blog eponymously called The Ocelloid. I couldn't agree with her more. The ocelloid is the structural and functional equivalent of the sophisticated eye of metazoans — and occurs in an unicellular organism! If you can think of anything that is "awesomer" than that, please let me know.

In the parade of startling facts of biology, one that stands out is the variety of morphologically complex structures made by the protists. Some have a mouth, a gullet, a bladder-like contractile vacuole, an anus, one of a variety of organelles of locomotion including some that look like legs, and yet other complex structures (what, no brain?). This begs the question: why did they not go the multicellular route? What more can unicellular organisms achieve?

But even in this wonderland, the ocelloid takes the cake (even though my spellchecker keeps changing it into "ocelot"). Being a miniature likeness of the vertebrate eye, it attains extremes of biological intricacy. Darwin considered the eye to be hugely complex ("... of extreme perfection and complication"), although not irreducibly so. He wisely noted: "I may remark that, as some of the lowest organisms, in which nerves cannot be detected, are capable of perceiving light, it does not seem impossible that certain sensitive elements in their sarcode should become aggregated and developed into nerves, endowed with this special sensibility". ("sarcode" is an old term for the protist cytoplasm). The repeated evolution of the eye from a primitive light-sensing device has been convincingly discussed. What is remarkable about the ocelloid is that it represents a colossal jump from a simple photoreceptive layer one finds in many unicellular organisms to a remarkably intricate structure — still within a unicellular organism. The ocelloid is found in some dinoflagellates only and is indeed a unique structure in nature.

The ocelloid's anatomy tells all. It is a roundish body about 20 µm in diameter (roughly 1/5 to 1/10 the length of the cell that bears it), endowed with a cornea-like cover, a prominent lens (called the hyalosome) bounded by iris-like constriction rings, and a complex retina-like body that is concave in shape. You will agree the analogy to a metazoan eye is startling, even if its diameter is nearly 1000 times less than that of the human eye. It makes you wonder if these organisms may develop cataracts in old age!

A new paper from labs in Japan, Switzerland, Taiwan, and Saudi Arabia goes into detail regarding the structure, function, and evolutionary origin of the ocelloid. The retinal body gets particular attention. This "organ" consists of an array of parallel lamellae that are ~40 nm thick in the light and ~50 nm in the dark. The structure resembles the thylakoids, the photosynthetic stacked membranous compartments of chloroplasts and cyanobacteria. The number of lamellae increases in the dark, as does the surface area of the retinal body itself. Thus, the ocelloid responds to light conditions although, oddly perhaps, the cells that bear it are not photosynthetic and lack chloroplasts. It remains to be seen whether the ancestor of the ocelloid-bearing dinoflagellate was a photosynthetic microbe that eventually donated its chloroplast to become the retinal body.

In many organisms, the cytoskeleton is involved in changing the conformation of photoreceptors in response to the light. Here, actin is found only in the retinal body and its changes in its morphology are inhibited by cytochalasin B, an inhibitor of actin polymerization, which suggests that actin is involved in the response to light. Actin is not found in the lens, which is thus unlikely to change shape. To complete the picture, does the ocelloid contain light sensitive pigments? Indeed it does, in the form of rhodopsin. By in situ hybridizations with probes to its mRNA, the authors found a rhodopsin-like gene in the retinal body only, which suggests that rhodopsin-like sequences are translated at this site.

Recapping, the ocelloid has the structural, and likely also the functional, properties of an eye. Notably, it has a light receiving structure and, in front of it, a refractive lens. As shown by micro-optometry measurements, the lens facilitates light perception in the dim light habitats of these dinoflagellates by concentrating the light on the receptor surface. Just why they like such light conditions is no quite clear.

Where does the ocelloid come from? Like most respectable organelles, it contains DNA (which, best I can tell, still awaits sequencing). Other evidence for this? The ocelloid is surrounded by a double set of membranes, can be seen dividing, and its retinal body has a thylakoid-like structure likely derived from a chloroplast. The rhodopsin gene appears to be of bacterial origin, hinting that it was acquired by horizontal transmission, possibly from a bacterial ancestor. It is thought that the ocelloid increased in complexity during the evolution of these dinoflagellates. For studies of the molecular phylogeny of this group, see here and here.

Why have these dinoflagellates gone to all this trouble? What do they want to 'see'? The answer is not clear. This group of microalgae is not photosynthetic, so they are not looking for light to support an autotrophic existence. Like other protists, they have embarked on extremely sophisticated evolutionary ventures. This particular group, the Warnowiids, have other extraordinary structures besides the ocelloid, structures such as a "piston" — a long posterior 'tentacle' that rapidly contracts and expands, presumably for cell motility — and nematocysts — ejectable barb-like structures used by jellyfish, corals, and sea anemones to capture prey.

The lesson? I suppose that this story of miniaturization pushes the limits of the awesome things that living organisms can do. So much for thinking of unicellular organisms as being "primitive". And yet the question still haunts one: why did these multitalented protists not follow the multicellular path?


Spectacular Convergence: A Camera Eye in a Microbe Imagem12
Comparison of warnowiid oscelloid (1) and the vertebrate eye (2) by Hayakawa et al., 2014.

Spectacular Convergence: A Camera Eye in a Microbe Ocello10
Illustration of the ocelloid eye of the dinoflagellate Nematodinium 
The lens-like structure in the ocelloid is a structure called a hyalosome, and appears to be made from a common cellular structure called a vesicle — which is a membrane-bound sac. The iris-like structure in an ocelloid is formed from something called a thylakoid. A thylakoid is a flattened pigmented sac where the light reactions of photosynthesis occur.
And the all-important retina, the structure in our eye that receives and processes light into chemical signals, has a similar structure in Warnowiids made of a photosynthetic organelle called a plastid. The photosynthesizing chloroplast in all the green plants we are familiar with, is one example of a plastid.

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