Seeing in the Dark and the Green: How Eyes and Leaves Share a Lighty Secret

The world of biology reveals surprising connections, and the human eye and a seemingly ordinary leaf share a fascinating one. Both organs rely on sophisticated light-sensing mechanisms to function effectively in their environments, despite their vastly different purposes.

Within the human eye, the retina houses two crucial photoreceptor cell types: rods and cones. Rods, responsible for low-light vision, utilize rhodopsin, a specialized protein, to capture even the faintest light signals. Cones, responsible for color vision, rely on various forms of iodopsin to differentiate colors in bright light conditions. Both rhodopsin and iodopsin function by undergoing a shape change upon encountering light, triggering a biochemical cascade that ultimately translates light energy into electrical signals the brain interprets as vision.

Plants exhibit a similar strategy. Nestled within their leaves lies phytochrome, a remarkable molecule that, like its counterparts in the eye, acts as a light receptor. Phytochrome exists in several states depending on the specific wavelengths of light it absorbs. By sensing variations in light intensity and spectrum, phytochrome provides the plant with vital information about its surrounding environment. This information plays a critical role in processes like photosynthesis, where plants utilize sunlight as an energy source, and regulates growth patterns based on light availability.

In both the eye and the plant, the photosensors function together with chromophores: retinal in the eye and phytochromobilin in the plant.

This unexpected parallel between the human eye and the leaf underscores a fundamental principle in biology – the ability to detect light is a powerful evolutionary advantage. By harnessing the power of light, both humans and plants gain the ability to navigate their environments, grow, and thrive.

"Survival of the fittest" is often misunderstood. It was originally meant to imply that the most well-adapted species prevail, not necessarily the "fittest" species. This means that the success of certain traits is not solely dependent on the efficiency of those traits. Rather, it is a complex interplay of environmental conditions, competition, pests, and much more. The success of a trait can largely depend on luck, such as favorable conditions for its spread within a stable population or its extinction due to an event. The fragility of populations is evident in the many species currently facing extinction—evolutionary marvels that suddenly disappear. Traits may take millions of years to develop or may never emerge again. When applied to humans, this is an important realization as it undermines race theories and eugenicist ideologies. The sole basis of these dehumanizing ideologies is a perceived superiority easily refuted by evolutionary insights. There is no basis for considering any physical traits as inferior. However, there is a good reason why this argument is rarely heard: a discussion about the value of human life is incompatible with insights from ethical philosophy. Human dignity is inviolable, and every individual determines their own worth. A discussion about the value of human traits or peculiarities should not even be entertained, as such a discussion is inherently undignified. Unfortunately, there are increasingly societal concepts that garner support with antiquated and dehumanizing views. It is important to employ reason and humanity to oppose such developments.

The howling honey worm is the neotenic larvae of the sugar dragon. It only develops into adulthood in very rare cases. It smells like cinnamon and cucumber. I don't know more yet, but it's howling all the time. Maybe some nice words would make it feel better. The drawing is from 2007.

The snifftong is a furry animal from planet Aromaoma. It feeds on smells, which it licks up with its nose tongue. Everything on Aromaoma feeds on smells. Also this flower. Right now. The drawing is from 2007.

Some may ask why, I ask why not! This is a fish with a palm in its mouth (drawn 2007).🌴🐟 Any questions?😝😝😝

As a kid, I always loved to watch the "Bionic Six" on TV. "Bionic, Bionic Six uh-oh-uh-ooh!" 😆😆😆
In 2007, I just invented the "new BIONIC 2.0"! 🤔😅🙃

This is a titmel. It's been first described in 2007. Other than camels, it lives in the mangroves only. When the flood comes, it sticks its long trunk inside a tight and wet hole. The thickening at the tip of the trunk serves as an anchor. At the back it has two huge humps which always float on the surface. They feel very nice. Because the titmel can't breathe underwater, there's a nose on each hump. It can't flee in water, so it follows a very interesting defense strategy. If an enemy appears (mostly sea cucumbers), it sprays milk out of its noses. That's very confusing for the enemy, because milk signals offspring. Every predator knows not to fight a feeding mother. When living at land, this weird animal behaves almost like a common rabbit. Always hopping around, looking for huge carrots and fresh holes. Scientists still try to figure out the reproductive system of that species. There's no evidence for sexual reproduction yet. It seems as if they just appear out of random holes in the swamp. Scientists definitely need to dig much deeper, harder and faster!

Barramunda / Australian lungfish
(Neoceratodus forsteri) in the Frankfurt Zoological Garden.

There are 6 species of lungfish in the world, of which the Australian is the most primitive. The lungfish morphology has hardly changed in the last 100 million years and therefore, like the closely related coelacanths, are considered living fossils.

Genetic studies, as well as the skull structure, the arrangement and shape of the fins, the approach of separation of oxygen-rich blood from the lungs and oxygen-poor blood from the body, suggest a close relationship to the tetrapods, to which we also belong.

Netherless, the lungfish aren't considered our ancestors, but are closely related to them.