How life's forms modify and evolve the Earth (Introduction)

by David Turell @, Friday, September 01, 2023, 19:57 (33 days ago)

Noted early on by Darwin:

"if Earth had never come alive, it would be a profoundly different world. Conversely: the planet of today has, to a remarkable extent, been made what it is by the activities of lifeforms. Over the course of the planet’s long history, a history that extends back more than 4.5 billion years, lifeforms have shaped the rocks, the water, the air, even the colour of the sky. A Never-Life Earth would not even have as many different kinds of minerals.

" The central that, over time, lifeforms have profoundly altered the fabric of this planet, and this, in turn, has altered the circumstances in which lifeforms evolve.


"Darwin’s first scientific monograph and his last – the two bookends of his thoughts, so to speak – were both about how animals have, over vast spans of time, transformed the landscape.

"These two works of biogeology – one on coral reefs, the other on earthworms – were, as far as I know, the first detailed studies of the subject ever published. On casual inspection, they appear to be unrelated undertakings, just part of Darwin’s long and eclectic list of interests, along with barnacles, orchids, carnivorous plants,...and other animals, the volcanoes of South America, and so on...The Structure and Distribution of Coral Reefs appeared in 1842, while his book on earthworms, The Formation of Vegetable Mould, Through the Action of Worms, with Observations on Their Habits, came out in 1881, about six months before he died. (Vegetable mould is what you and I would call topsoil.)


"Darwin suggested instead that atolls form on the slopes of volcanoes that are slowly sinking. Here’s a brief sketch of the idea. A volcano erupts and builds an island in the middle of the ocean. Coral animals settle on its slopes, luxuriating in the warm, shallow, sunlit waters, and begin building the limestone skeletons that, together, will form a reef. If the seafloor then begins to subside, the volcano will gradually sink back beneath the waves – but the corals will continue to grow upwards, so as to remain in the shallows. As long as the volcano doesn’t sink too fast, the corals can keep pace with its descent.


"Eventually, the volcano may vanish far beneath the waves, leaving just the coral as a marker of its existence. Each atoll is a requiem for a volcano. Or, as Darwin wrote – ‘a monument over an island now lost’.

"His argument makes a clear prediction: somewhere beneath each atoll, beneath these immense piles of life-built rock, these mountains of limestone, you will find the remnants of a volcano.


"In the 1940s and ’50s, the United States government tested dozens of nuclear weapons in the Marshall Islands, a cluster of atolls that lie in a remote part of the Pacific a little to the north of the equator. This brought a host of scientists – geologists, biologists, oceanographers – to study the area. In 1952, a team of geologists drilled deep into Enewetak Atoll. At 1,283 metres (4,208 feet), they struck basalt. Volcanic rock. Darwin was right.


"his book on earthworms, The Formation of Vegetable Mould, Through the Action of Worms, with Observations on Their Habits, came out in 1881, about six months before he died...At the time, the book was wildly popular, selling 3,500 copies within the first month. Today, though, it is little read, and often dismissed as the eccentric afterthought of a great man whose life was drawing to a close.


"His uncle speculated that this was due to the activities of earthworms. As they burrowed through the soil, the worms were, his uncle suggested, acting as slow-motion ploughs. Altogether, the observations were so interesting that William Buckland, an eminent geologist of the day, suggested that Darwin had identified ‘a new Geological Power’.


"Earthworms burrow through soil by eating it; they also nibble on organic matter such as dead leaves. To defecate, they generally come to the surface, where they eject, as Darwin put it, ‘little intestine-shaped heaps’ known as castings. On the basis of his conversations with his uncle, Darwin suspected the worms of tilling the soil, bringing fine particles from deep in the ground up to the surface.


"Taking his results together, Darwin showed that earthworms have several important effects. The animals do not just mix the soil by bringing deeper material up to the surface. By munching on fallen leaves, and by pulling those leaves down into their burrows, they also create new soil and enrich it with a nutritious compost.


" Darwin: "The plough is one of the most ancient and most valuable of man’s inventions; but long before he existed the land was in fact regularly ploughed, and still continues to be thus ploughed by earthworms."

"Worms might appear insignificant, but because there are so many of them, little by little, they sculpt the contours of the world.


"At the end of his book, he remarks: ‘It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures.’ In this, however, he profoundly underestimated the scale of the changes wrought by other lifeforms."

See life forms II.

How life's forms modify and evolve the Earth II

by David Turell @, Friday, September 01, 2023, 20:15 (33 days ago) @ David Turell

This is the non-Darwin part:

"First off, the tilling processes that Darwin described are not limited to earthworms, with different burrowing animals having effects at different scales. Ants, for example, tend to bring up the finest grains of sand or soil. In Berlin, where I live, you often see small piles of fine sand heaped along the edges of cobblestones, and if you look closely, you will often see ants hard at work. Although the grains are typically brought up a few at a time, in places the ants are so abundant that they will shift many tonnes of soil per hectare per year. In one study that was directly inspired by Darwin’s work on earthworms – Geologic Work of Ants in Tropical America (1910) – the author, John Casper Branner, estimated that ants in Brazil were responsible for moving considerably more soil per hectare each year than earthworms in England. Meanwhile, larger burrowing animals such as badgers excavate huge mounds of earth, creating hillocks that can last for centuries, to say nothing of the earth-shifting activities of bandicoots, beavers, chipmunks, gophers, meerkats, mice and moles, or of burrowing birds and burying beetles.

"And it’s not just on land. As you walk to the sea across that part of a beach or mudflat that’s covered by waves when the tide is high, but exposed when the tide is low, you may see tiny crabs, no bigger than your fingernail, excavating burrows one armful of sand at a time. Don a mask and look beneath the waves, and you’ll find an incredible variety of animals digging burrows.

"Moreover, burrowing animals are not the only lifeforms to have a substantial planetary impact. Far from it. Before the evolution of the first trees, around 400 million years ago, rivers were far less likely to boast meanders and oxbows and other features that allow them to dawdle their way to the sea. Plants have also contributed a great increase in mud. Ancient reefs and banks of shells have not only left a legacy of enormous piles of limestones, they also have altered the shapes of mountains: as rocks go, limestones are relatively malleable, so when ancient reefs and banks of shells are crushed and cooked as mountain chains are upheaved, the presence of limestones will affect the way the mountains fold. The more limestones, the more folds. Limestones so treated will also, often, become crushed and cooked into marble. Many of the world’s greatest sculptures and monuments have been created from rock built by life and then transformed by Earth as it builds mountains. Next time you look at Michelangelo’s David, remember that it was built from marble formed from crushed life-rocks, as were many of the grandest buildings and structures of ancient Rome.


"First, certain species of archaea are responsible for the biological generation of methane, a greenhouse gas, which warms the climate. Second, no conversation about the impacts of lifeforms upon the planet would be complete without mention of the cyanobacteria. These lifeforms, formerly known as blue-green algae, are, in my view, the most important lifeforms in the history of the planet. At the time they evolved, more than 2.3 billion years ago, Earth had no oxygen molecules in the air to speak of. Instead, all the oxygen atoms were tied up in the water and the rocks. Cyanobacteria evolved to use the radiant energy of the Sun to split water molecules apart, a process that roughly halfway through the history of Earth would result in an atmosphere that contained oxygen molecules.

"Back then, the atmospheric oxygen would not have been adequate to support you or me. Yet its very appearance had several transformative effects. As oxygen is reactive stuff, its arrival led to a proliferation of new minerals. Indeed, Earth began to rust. At the same time, the advent of oxygen led to the creation of an ozone layer, which protects the planet’s surface from the most harmful rays of the Sun. The presence of this layer fundamentally changed the circumstances in which lifeforms on land subsequently evolved. And since the colour of the sky is a consequence of the composition of the atmosphere, lifeforms have also reached out and painted the heavens above.


"..the Never-Life Earth would not be the Earth of today, just without the green. It would be profoundly different: an alien planet. A human, or some other animal, magicked there would be killed in an instant, overcome by suffocating air and lethal levels of radiation.

"It would be a planet not merely lifeless, but deadly."

Comment: in the evolution of this planet a broad diversity of living organisms has played a major role. I view it as God guiding the formation of the Earth to be the perfect planet for life to appear. (See Privileged Planet thread) Then diverse life forms helped transform the Earth into its present state. A very emotional and well-written essay should be read in its entirety.

How life's forms modify and evolve the Earth: whale poop

by David Turell @, Sunday, September 03, 2023, 15:32 (31 days ago) @ David Turell

Stays near the surface supplying nutrients:

"What makes whale poop special? First, there’s a lot of it, since whales are the largest animals on Earth. Second, whales usually feed in deeper water and then poop when they surface to breathe; this cycles nutrients like nitrogen, phosphorus and iron — which naturally sink.

"Third, their fecal plumes are buoyant, lingering in the sunny, uppermost layer of water. This means whale poop could help spur the growth of phytoplankton, tiny plants at the base of the marine food web.


"The recycling of nutrients via cetacean poop is called the “whale pump” and has been studied in other parts of the world, too.

"In the North Atlantic, for example, researchers Joe Roman and James McCarthy found that whales and seals in the Gulf of Maine may be responsible for adding more nitrogen to the surface each year than all of the rivers combined.

"And according to a different study co-authored by Roman, the vertical movement of phosphorus from the deep sea to the surface by marine mammals has been reduced by 77 percent worldwide since whaling drastically reduced cetacean populations.

"In the Southern Ocean, feces from fin, sperm and blue whales replenish iron at the surface — a necessary ingredient for phytoplankton growth. A 2010 study found that the iron content in the fecal matter of baleen whales there was 10 million times higher than in background Antarctic seawater.

"Whale poop likely plays an important role in fertilizing the cold waters of the North Pacific, too. An estimated 1,500 humpbacks migrate to Southeast Alaska every summer to feed, along with gray whales, orcas and other marine mammals.


"In addition to boosting nutrients, whale poop may also play a role in sequestering carbon. “There’s this idea that phytoplankton are helping draw carbon out of the atmosphere and sink it into the deep ocean where it won't return to the surface for thousands of years,” says Pearson.

"Some scientists are even attempting to use artificial whale poo to boost both fish populations and phytoplankton growth, in hopes the marine plants absorb more carbon dioxide from the atmosphere.

"Pearson co-authored a recent paper that estimates the amount of carbon sequestered by the whale pump. But she cautions that “to fully realize these benefits, we need to be talking about stringent conservation actions that allow whale populations to recover.”


"One way to inspire more conservation is to help people “look at whales in a different light,” says Pearson. This includes putting numbers on how much they contribute to ecosystem health through nutrient cycling or carbon sequestration. (my bold)

"Which brings us back to Bloch in her small boat, scooping up bottles full of whale poop. She also hopes the findings will tell us more about how these gentle giants affect the food web, and give us even more reasons to protect whales. (my bold)

Comment: everything an animal does has some effect on its ecosystem. Every ecosystem has effects on other ecosystems in an enormous interconnected web over the Earth.

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