The wood oats (Chasmanthium latifolium) whose tawny dry stalks I had photographed in January have re-emerged from the ground with broad green blades and seeds just beginning to develop. Along a roadside rich in European “weeds”, wood oats are native to the Southeast, produce edible seeds, and have even been cultivated as a grain.
Animal hairs on a barbed-wire fence glow in the evening light along Piney Woods Church Road.
A lone blackberry leaf catches the late afternoon light. I am entranced.
Earlier today, I walked Piney Woods Church Road in search of reminders of last night’s rain. I did not have to look far. Tiny droplets of water cling to the edges of this plantain leaf, illumined by the mid-morning sun.
On a sunny late-spring morning after a rain, I pause to celebrate the simple forms and colors of leaves and sky.
On a cloudy early morning in late spring, a few English Plantain flowers bloom in a Piney Woods Church Road pasture.
An hour or so before sunset along Piney Woods Church Road, I took this photograph of clouds illumined by the late-day sunlight, with a loblolly pine tree in the foreground. How I wish the clouds would bring us some rain!
“Caterpillar sheds his skin, to find a butterfly within,” Donavan sang in his 1967 Billboard #11 hit song, “There is a Mountain.” The tune, with its simple Buddhist-inspired lyrics and a lovely, catchy flute melody, was recently revived in a recording by Kenny Loggins. In the 2009 Disney music video, Loggins is encircled by joyful young children clapping and shaking tambourines. But metamorphism in insects is far from child’s play. In fact, Donavan’s picture is highly inaccurate. A caterpillar des not molt to reveal a butterfly inside. Instead, it forms a chrysalis, inside which the caterpillar’s body completely dissolves, reconstituting itself as an entirely new organism, a butterfly. Metamorphism in butterflies is much closer to the mythical phoenix rising from the ashes than an actor stepping out of one costume to reveal another one. It is as if two different actors are involved: one to play the role of the caterpillar, the other the butterfly. According to Darwin’s theory of evolution, this odd process developed gradually, in stages, over a vast amount of time. But have you ever stopped to wonder how that could have happened?
Frank Ryan’s 2011 publication, “The Mystery of Metamorphosis: A Scientific Detective Story” explores the question of how metamorphosis may have come about. Strangely enough, metamorphism in animals has not been studied as much as one might imagine. In fact, the currently dominant theory of gradual evolution does not work very well, particularly in cases of metamorphism that occur among invertebrates living in the ocean. And that is where the research of Donald Williamson comes in, and where “The Mystery of Metamorphosis” opens.
Donald Williamson has been studying for decades the larval forms of various sea creatures, including sea stars, brittle stars, sea urchins, and sea squirts. These organisms are classified by their adult forms, because often their larval forms are nothing like the adults. What is even more odd is that not all of the species of these organisms actually undergo metamorphosis at all. A few do not. Others go through very strange metamorphoses indeed. One sea star, Luidia sarsi, has a bilaterally symmetrical, free-swimming larva. Inside the gut of this larva, a tiny adult sea star develops. The larva does not change into the adult. Instead, the larva eventually “births” the adult form, and then continues living for a time on its own, without reproducing. Eventually, the radially symmetrical adult sea stars will reach sexual maturity, broadcast egg and sperm into the water, and the result will be a new generation of larvae.
Then there are the sea squirts. As adults, they look like strange glass tubes attached to the sea floor or perhaps a boat bottom, where they spend their days pumping water into their bodies through one opening and releasing it through another. With the exception of a few diehard couch potatoes, there is no human equivalent to this sessile, brainless organism. As larvae, however, sea squirts resemble miniature tadpoles, with primitive brains and spinal cords. Inside the larval tissues, the adult form begins to develop, almost like a parasite – as if there were two different organisms involved rather than just one. When they are ready to become adults, sea squirts sense the presence of a suitable substrate to attach to, point their bodies head-downward, and begin to lose all of their larval properties. Their tail dissolves, and so do their brains – all to be reconstituted in the adult form.
Studying these odd forms, Williamson proposed a daring evolutionary explanation. What if, early in the history of life, species boundaries weren’t as tightly defined as now? What if organisms were able to hybridize with other organisms of different species, different classes, perhaps even different phyla altogether? Since reproduction took the form of broadcast spawning, it would have been possible – quite likely, in fact – that there were many pairings of egg and sperm from entirely different organisms. If some of these pairings were successful, the result could have been a new organism, maintaining characteristics of both of its forbearers. In such a way, organisms might have developed larval forms that they did not have previously. Imagine the creative potential of a world where cross-hybridization took place! As Ryan relates toward the end of his book, we might not need to imagine that condition at all. Instead, we can look to the fossil record for evidence of just such a possible past, toward the dawn of multicellular life, over 500 million years ago.
Ryan’s book is captivating, even a bit jarring, with its proposal that there may be much more to evolution than the gradualist model proposed by Darwin. “The Mystery of Metamorphosis” is an excellent reminder that there is much that is still unknown, that the development of life on Earth still holds many wonders to explore. It is not easy going, particularly for the reader not schooled in biology in general and the nature of insect homones in particular. But it is worth the journey to explore such wild ideas as these, ideas that conventional Darwin’s Theory of Evolution by Natural Selection might declare impossible. But as Shakespeare observed in “Hamlet”, “There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.”
This article was originally published on August 19, 2011.
Today was, without doubt, the most difficult day I have experienced in my photo-odyssey thus far. A couple of pulled muscles and tendons in my left leg required me to drive to Piney Woods Church Road yesterday, hobbling my way along only half the distance of the road. Today, the leg had worsened considerably, to the point that I could put practically no weight onto it at all. For a few minutes, I actually considered the prospect of abandoning the enterprise. Just getting from my office to the back door of the house was a frustration; getting across the yard and driveway to the car took several minutes. I arrived at the car, lifted my leg by the sock top to place it in the car (it is too weak to lift without support), and realized I had forgotten my car key. Fortunately, the cell phone was in the car, so I was able to call my wife in the house (easily the shortest-distance call I have ever made) and ask her to bring it to me. I abandoned all thought of getting out of the car and attempting a brief roadside hobble; I settled instead for taking photographs out the open window of the Prius. Fortunately, a neighbor provided a ready-made subject for the camera — a new horse fence along the roadway, completed just this past week. Here’s hoping I will be back up to at least a few minutes of groundwork by tomorrow afternoon.
Early this afternoon, I stopped at a patch of daisy fleabane along Piney Woods Church Road, discovering a variety of flying creatures busily at work gathering nectar and pollen and, in turn, pollinating the daisies. Perhaps daisy fleabane is merely a common weed to many, but right now along this stretch of roadway, it is virtually the only flower actively blooming, providing much-needed nourishment for bees and flies alike.
