|Annelida||Little ring||Segmented worms||Multiple circular segment||16,300 extant approx|
This is a subject of but small importance; and I know not whether it will interest any readers, but it has interested me.
December 30, 2010 12:20 AM Subscribe
Bioturbation refers to the biological reworking of soils and sediments, and its importance for soil processes and geomorphology was first realized by Charles Darwin, who devoted his last scientific book to the subject. Here, we review some new insights into the evolutionary and ecological role of bioturbation that would have probably amazed Darwin. In modern ecological theory, bioturbation is now recognised as an archetypal example of ‘ecosystem engineering’, modifying geochemical gradients, redistributing food resources, viruses, bacteria, resting stages and eggs. From an evolutionary perspective, recent investigations provide evidence that bioturbation had a key role in the evolution of metazoan life at the end of the Precambrian Era. Bioturbation from an evolutionary perspective. The evolution of landscapes and seascapes: Darwin was the first to realize that small-scale reworking activities by tiny invertebrates could have dramatic consequences at far larger scales, such as in the process of landscape formation. However, Darwin’s concept of a biological imprint on the landscape was not picked up initially by geologists and geographers and, for more than a century, strictly physical and chemical views on Earth surface processes dominated textbooks and theories. Only in recent decades has bioturbation been ‘rediscovered’ as an important factor in landscape evolution, most prominently through its influence on soil formation, erosion and hill-slope stability. The production of soil through the breaking down, erosion and then transport of bedrock has been shown to be due primarily to biogenic disturbance. Root growth and animal burrowing disrupt bedrock that is abiotically weathered but structurally intact; this then creates smaller particles and more surface area for weathering to act upon. Biological reworking also loosens the soil, which counteracts consolidation. This stimulates downslope creep and lowers the infiltration rate of water, making the soil more prone to erosion. Over longer timescales, this leads to a smoothing of the landscape, flattening hills and filling up valleys, resulting in an increased sediment transfer by rivers from the land to the oceans.
RECORD: Darwin, C. R. 1838. On the formation of mould. [Read 1 November 1837] Proceedings of the Geological Society of London 2: 574-576. A paper was afterwards read “On the Formation of Mould,” by Charles Darwin, Esq., F.G.S. The author commenced by remarking on two of the most striking characters by which the superficial layer of earth, or, as it is commonly called, vegetable mould, is distinguished. These are its nearly homogeneous nature, although overlying different kinds of subsoil, and the uniform fineness of its particles. The latter fact may be well observed in any gravelly country, where, although in a ploughed field, a large proportion of the soil consists of small stones, yet in old pastureland not a single pebble will be found within some inches of the surface. The author’s attention was called to this subject by Mr. Wedgwood, of Maer Hall, in Staffordshire, who showed him several fields, some of which, a few years before, had been covered with lime, and others with burnt marl and cinders.
Earthworms was Darwin’s last book. It was published on 10 October 1881, just six months before he died, and was reviewed enthusiastically in The Times that day praising Darwin for exalting ‘them of low degree’. The book was an instant success and remains a significant part of Darwin’s oeuvre. It is written in a clear, informal style and betrays, perhaps more than any of his other books, Darwin’s true delight in engaging with nature. Such was Darwin’s fame at the time the book appeared that the satirical journal Punch ran one of their ‘fancy portraits’ showing the wise old Darwin, sitting like a little girl in a garden, pondering a giant worm floating above him in the shape of a question mark. The caption states that Darwin ‘has lately been turning his attention to the “Politic Worm”’. Darwin’s young protégé George Romanes, to whom he had entrusted some unpublished parts of his ‘big book’ on species, reviewed Earthworms in the weekly science journal Nature on 13 October. Romanes focused on Darwin’s astounding and totally original proofs of the intelligence of worms, while at the same time demonstrating that they were deaf and blind. Romanes cited, for example, Darwin’s experiments proving that worms selected which part of a leaf to pull down first into their burrows. Visitors to the Darwin Museum at Down House, his home from 1842 onwards, can today see the trappings of some of these experiments, such as the bassoon in the drawing room used to test worms’ response to deep notes. Another such worm-related item at Down House is a replica in the garden of the ‘worm stone’. This was used to measure the rate that stones sink slowly as worms digest the soil and deposit it above ground as worm casts, giant examples of which from around the world Darwin illustrated in his book.
Earthworm grunting: In this competition
Also known as worm snorers and worm fiddlers, they catch earthworms for fish bait by plunging a wooden stake into the ground and rubbing it with steel. The resulting sound drives worms aboveground, though the scientists didn’t know why — until now. All this fiddling, snoring and grunting, found Vanderbilt University biologist Ken Catania, amounts to one thing: the sound made by burrowing, worm-hungry moles. Darwin himself suspected as much. “It is often said that if the ground is beaten or otherwise made to tremble worms will believe that they are pursued by a mole and leave their burrows,” he wrote in The Formation of Vegetable Mould through the Action of Worms, a book that is largely forgotten but reflects his enduring and instructive fascination with a creature that most people, then as now, ignore.
http://www.fossilmuseum.net/Tree_of_Life/kingdom_animalia.htm http://www.scientificpsychic.com/etc/timeline/time-machine.html http://www.scientificpsychic.com/etc/timeline/timeline.html http://www.wormdigest.org/content/view/475/2/
‘Pediareview: Cambrian Substrate Revolution, Cambrian explosion, Cambrian Substrate Revolution, Darwin, from Insectivorous Plants to Worms; Understanding‘life on mats’, biogeochemistry song in French , How the Worm Turns By AMY STEWART, ant bioturbation unearthed! Earthworms’ bodies are made up of ring-like segments called annuli. The annuli are covered in small hairs that help in moving and burrowing.
EXPERIMENTAL NEOICHNOLOGY Darwin on worms: the advent of experimental neoichnology S. George Pemberton’ and Robert W. Frey Darwin’s book on worms is much more than a description of the formation of “vegetable mould” (or soil) by earthworms: it is a treatise on experimental neoichnology. The book can be divided into three parts; the first concerns details of the ecology, physiology, and activities of earthworms; the second deals with the effects of burrowing by earthworms on soil formation and burial of objects by those activities; and the third section deals with denudation of the land by burrowing activities of worms. What makes this work special, however, is the novel way in which Darwin set out to prove his hypothesis of 1837. In order to accomplish this task, Darwin devised numerous experiments, some of which ran for more than 30 years. He was, therefore, able to acquire quantitative data that are difficult to generate even today.
As recognized already by Charles Darwin, animals are geobiological agents. Darwin observed that worms aerate and mix soils on a massive scale, aiding in the decomposition of soil organic matter. A similar statement can be made about marine benthic animals. This mixing, also known as bioturbation, not only aides in the decomposition of sedimentary organic material, but as contended here, it has also significantly influenced the chemistry of seawater. In particular, it is proposed that sediment mixing by bioturbating organisms resulted in a severalfold increase in seawater sulfate concentration. For this reason, the evolution of bioturbation is linked to the significant deposition of sulfate evaporate minerals, which is largely a phenomena of the Phanerozoic, the last 542 million years and the time over which animals rose to prominence.
NIOO-KNAW’s (The Netherlands Institute of Ecology) department Ecosystem Studies is engaged in detailed research on the influence of bioturbation of the sea bed. Very little is known about exactly how this works, and it’s important to find out more, so that in future if an important burrower like the lugworm disappears because of climate change, we will better be able to predict the impact this will have on the entire ecosystem. Another interesting aspect being studied by means of computer models is the relationship between the carbon cycle and the bioturbation of the sea bed. Some of the greenhouse gas carbon dioxide (CO2) now present in the atmosphere in enhanced amounts is absorbed by the oceans, where it is converted into organic matter and sinks to the ocean floor, where it is stored in yet another form. Until recently it was thought that the most important factor in this chemical transformation was bacterial action, but it now turns out that it’s probably bioturbation that is crucial in the buffering of carbon in the ocean floor. A startling finding of the NIOO-KNAW research (see attachement: publication 2007 in TREE) is that bioturbation has played a crucial role in evolution. The NIOO-KNAW scientists have been able to demonstrate the major importance of burrowing for the period at the beginning of the Cambrian – over 540 million years ago – when many new species of animal appeared on the ocean floor and the development of life on Earth gained momentum. Researcher Filip Meysman explains: “The first multicellular animals from the Precambrian were basically wimps, who filtered algae from the water or grazed on the microbial mats carpeting the ocean floor. At the start of the Cambrian, we find that some of the animals were eating other animals. The first predators were evolving, kick-starting an arms race. Their prey began to protect themselves with armour and prickles, and hid themselves in the sediment on the sea floor. The predators reacted by developing weapons of attack and following their prey into the sediment. From this we conclude that the ocean floor underwent drastic changes at that time: a veritable ‘excavation revolution’. The stable microbial mats of the Precambrian disappeared and were replaced by the churned-up ocean floor we know today. So, the ocean’s bottom dwellers had to adapt to this new environment. In this way, bioturbation was a driving force for rapid evolution.” These new insights into bioturbation fit in nicely with the ideas of Charles Darwin, the originator of the theory of evolution. Over 125 years ago he was the first to point out the importance of burrowing earthworms. In his last book The formation of vegetable mould, through the action of worms, with observations on their habits, published in 1881, Darwin described the role played by earthworms in soil formation and erosion, and their impact on the landscape. The book is largely based on experiments Darwin carried out in his garden, assisted by members of his family. Filip Meysman elaborates: “Darwin’s book gave the general public insight into the importance of soil organisms. Up until then, earthworms and their like were thought of as pests. Darwin himself found the topic interesting, but not very important. He had no idea of the critical role burrowing organisms played in evolution. What we now know about the influence of bioturbation on biodiversity and evolution would probably make him fall off his chair in astonishment.”
In his Autobiography, Charles Darwin (1809–1882) briefly commented on his last major publication in the following words: “I have now (May 1, 1881) sent to the printers the MS. of a little book on The Formation of Vegetable Mould through the Actions of Worms. This is a subject of but small importance; and I know not whether it will interest any readers, but it has interested me. It is the completion of a short paper read before the Geological Society more than forty years ago, and has revived old geological thoughts” [1, page 136]. In a foot-note on the same page, Darwin’s son Francis (1848–1925), who edited the letters as well as other documents after his father’s death, remarked that “between November 1881 and February 1884, 8,500 copies were sold.” Charles Darwin’s “little book”  later gave rise to the scientific concept of “bioturbation”, which can be defined as “the biological reworking of soils and sediments by all kinds of organisms, including microbes, rooting plants and burrowing animals” . These ongoing activities of different soil (or sediment) organisms, which leads to a modification of geochemical gradients and the redistribution of organic substances, can be viewed as a kind of “ecosystem engineering.” Moreover, it is obvious that soil texture is modified and different soil particles are dispersed . In this article, we review the history and current status of Darwin’s “earthworm research-agenda” (Figures 1 and 2), summarize the significance of his classical monograph  with respect to modern soil biology, and describe the ecology and biogeography of a rare, endemic species, Lumbricus badensis. The last section of our account is in part based on unpublished observations on this enigmatic annelid. …. It should be noted that Darwin’s monograph rapidly modified the perception of earthworms by society. Up to then, earthworms were considered by gardeners, agriculturists, and so forth, as soil pests that have to be eliminated—Darwin’s work changed this belief forever and finally led to the concept of bioturbation as well as the discipline of soil biology [3, 10, 13].
Brainy worms: Evolution of the cerebral cortex is directly related to our spineless ancestors. EMBL scientists uncover counterpart of cerebral cortex in marine worms.In humans, the cerebral cortex, the tissue-like outermost layer of the brain, is thought to play a critical role in creative and analytical thinking. But just how this portion of the brain evolved has remained a mystery. Now researchers report that something resembling a cerebral cortex exists in the marine ragworm, a small creature with ancient roots that has not changed in hundreds of millions of years. The findings appear in the journal Cell. and are being discussed in many places.Platynereis dumerilii, a marine polychaetous annelid or ragworm is considered a living fossil. -”Eyespots are found in the larvae of marine ragworm and are simplest eyes that exist. They resemble the first eyes that developed in animal evolution and allow the larvae to navigate guided by light. Studying the eyespots of Platynereis dumerilii, larva is probably the closest scientists can get to figuring out what eyes looked like when they first evolved“.
- If one likes doing more than reading, this year try something new, the year of small scale vermiculture.
[PDF] Manual on Vermiculture and Vermicomposting, Basic Guide to Worm Composting, Welcome to the World of Vermiculture(troubleshooting), Worm Composting—Everything you need to know to get started composting with worms ( Download PDF). The Art of Small-Scale Vermicomposting—Worm Digest’s Guide, includes worm biology, worm bin critters, harvesting your worm bin and compost tea. (PDF) More Options for Composting with Worms—Add worms to a plastic backyard compost bin. (Download PDF) Getting Started with the Can-O-Worms—Simplified directions for using a Can-O-Worms (Download PDF.) How to Use Your Worm Factory—Simplified directions for using a Worm Factory (Download PDF). Homemade Worm Bins—How to modify a plastic storage container for use as a worm bin. –did you know Daryl Hannah sells a pricey but conceptually spectacular bamboo worm bin, it sold out swiftly. Do Feed Fruit and Vegetable Scraps–Mold and rot are fine (the beauty of layering)! Avoid overfeeding citrus–should be no more than 1/5 of food, Coffeegrounds, filters and teabags, Egg Shells, Breads and Grains, Paper towels and Tissues Do Not Feed Meat, Fish, Dairy Products, Butter, Greasy Foods, Pet waste, Harvesting Worm Castings Vermicomposting – An Overview , wormwoman ,Harvesting Vermicompost Vermicompost & Worm Harvesting, the ‘Turbo Light Harvesting Method’ Vermicomposting - The Morgan Family Various Stages Of Vermicomposting Pt2 Vermicomposting: Changing The World 1000 Worms At A Time How to Make Your Own Worm Bin Building a worm farm DIY Worms Vermi Compost Part 1 DIY Worms, Vermi Compost Part 2 Playlist Vermiculture Improves Urban Farming in Argentina Lets get this out of the way first;
- a worm hatches
- Worm’s birth
- C. elegans mating
- C. elegans Embryogenesis
- High Speed Camera Acquisition C. elegans reproducing
- a worm hatches – in high resolution
- Worms hatching
- Worm Hatching From Egg 50x
- Fluorescent C. elegans nervous system
- C. elegans embryonic development – RNAi
- C elegans 4 to 8 cell Embryo development movie see optical sectioning in White Light
- In the Beginning… There Was C. Elegans
- Modeling a worm’s brain
|Classes and subclasses|
|Class Polychaeta (paraphyletic?)
Class Clitellata (see below)
Oligochaeta – earthworms, etc.
Hirudinea – leeches
Class Archiannelida (polyphyletic)