Earthworm

“ The very name Earthworm, so distinctive as it is of the habitat of these animals, seems to have been expressly invented in order to crystallise into one word the remarkable distributions of these creatures. They are with very few exceptions the most purely terrestrial animals that we know. There are a few Mammals like the mole and several underground Amphibians and Snakes in the tropics which share this habitat with the worms, probably because they chiefly prey upon them. But there is no group of animals that is characterised by a subterranean existence in the way that earthworms are. ”

“ Earthworms in Agriculture.—That the earthworm is of great service to the agriculturist is shown by the author of a paper, the substance of which we find in Die Natur. Not only does the earthworm not attack or injure the roots of plants; on the contrary, it aids them in their growth by excavating passages through which they can penetrate into strata otherwise inaccessible to them. And, as the overground portion of a plant is always proportioned to the length and number of its roots, it is plain that the earthworm is of great benefit to the plants in its neighborhood. ”

“ Time.—May or June, in connection with gardening, when the working of the worms in the moist soil of the garden is quite noticeable. [Pg 148]
Outdoor studies may be assigned, as:
Observe the loose soil at the entrance to the burrows. Insert a straw in the burrow and, following it, dig downward with a garden trowel and learn the nature of the earthworm's home.
Are earthworms ever found out of their burrows during the day? If so, on what kind of days? Why do earthworms burrow deep in dry weather?
Earthworms can breathe only when the surfaces of their bodies are in moist conditions. ”

“ They will eat scraps of meat by sucking the juices, and scrape off the pulp of leaves and root vegetables in much the same way. Much of their subsistence is upon organic matter that can be extracted from the soil. Quantities of earth are swallowed. It is rare that an earthworm is dug up that does not show earth [Pg 65] pellets somewhere on their way through the long digestive canal. The rich juices of plant substance are absorbed from these pellets as they pass through the body.
Earthworms explore the surface of the soil by night, and pick up what they can find of fresh food. ”

“ I think being an earthworm must be an interesting life. I wonder how it feels to stretch out long and then get short again. I went goes on, to pull weeds by the bean-folks. I went back some steps to look looks at them. Those bean-folks in the garden are such climbers. Their thoughts reach up toward the sky. And they climb up on the poles we put in the garden there.
By-and-by I saw another earthworm. He was alone. I did have sees of his movements. I always do see more earthworms after rain. This one was making himself very long. Lucian Horace Ovid Virgil, too, did have seeing of that earthworm. ”

“ Linnaeus recognized only one species of earthworm and named it Lumbricus terrestris. There are now one thousand well-characterized species known from different parts of the world, and the number increases almost daily. The earthworms of England belong entirely to the three genera Lumbricus, Allolobophora and Allurus, which are further subdivided by some systematists ”

“ The phosphorescent worms add to the splendors of the festivals of the nights along our shores, and are among the illuminators of the ocean; as bait they have a relation to the fisheries; leeches have a medicinal value, while the common earthworm is a valuable ally of the farmer. Darwin estimates that there are one hundred thousand earthworms in the upper six feet of every acre of ground in favorable localities, and in New Zealand three hundred thousand. ”

“ This is why earthworms are never seen above ground except on rainy days, and never in the top soil if it has become dry. In seasons of little rain, they go down where the earth is moist, and venture to the surface only at night, when dew makes their coming up possible.
Earthworms have no teeth, but they have a long snout that protrudes beyond the mouth. Their food is found on and in the surface soil. ”

“ They may be fed on bits of fat meat, cabbage, onion, etc., dropped on the surface. When studying live worms, they should be allowed to crawl on damp paper or wood. An earthworm placed in a glass tube with rich, damp soil, may be watched from day to day. ”

“ There are terrestrial forms among the lowest worms, at least forms that live in earth that is damp; but the earthworm is in the strictest sense a terrestrial animal. Darwin showed that it not only dwells in the soil, but is in a sense the manufacturer of soil, since the fertility of the earth depends greatly upon the work of earthworms. They pass the soil through their bodies, digesting the organic particles they find in it, and thereby loosen the soil, reduce it to a state of fine division, and render it more fit to support the growth of plants. ”

“ The behaviour of earthworms as a factor inducing soil fertility is discussed by Darwin in his well-known work on the subject, and their action may be briefly summarised as follows. In feeding habits they are very largely saprophagous, and consume decaying vegetable matter including humus, which they swallow, together with large quantities of soil. Earthworms come to the surface to discharge their fæces (“worm casts”) , and in this process they are continually bringing up some of the deeper soil to the air. ”

“ Again, the well-known action of earthworms may be said to be a biological work, but the resulting aeration of the soil causes edaphic differences, and earthworms are absent from certain soils, such as peat. The pollination of flowers and the dispersal of seeds by various animals are biological factors; but pollination and dispersal by the wind cannot be so regarded. The influence of man on plants and vegetation is also a biological factor, which is frequently ignored as such, and treated as if it were a thing apart. ”

“ Earthworms prefer cool temperatures, moist soil, humidity, relatively less sunlight and neither too coarse nor too fine sand. These are the ideal conditions that must be kept in mind when using them for vermiculture. Since earthworms breathe through the skin, they perish if their skin becomes dry or the quantity of mucus diminishes. Hence to keep earthworms alive in the vermicompost containers, care should be taken to ensure that the vermibed remains moist. Earthworms however do not prefer waterlogged soils. ”

“ Earthworms may be correctly called the great soil builders; they burrow through it, allowing the free passage of air and water; they swallow large quantities, which they eject on the surface in the form of “worm-casts,” the soil materials being well mixed in the process; they pull underground leaves and other parts of plants from the surface and so increase the supply of organic matter for the action of the micro-organisms that bring about decomposition. ”

“ Earthworms are very useful: they make burrows in the soil, thus allowing air and water to get in: they drag in leaves and they keep on covering the surface with soil from below. Besides these and the other large creatures, there are micro-organisms so small that they cannot be seen without a very good microscope: they live and breathe and require air, water and food. Some are very useful and change dead parts of plants or animals into valuable plant food. Almost anything that can be consumed by fire can be consumed by them. ”

“ In England, earthworms have done a great deal more toward burying boulders and ancient ruins than any other agency. They eagerly burrow under heavy objects, the weight of which causes them to crush the honeycombed earth. Undiscouraged, the earthworms repeat their work.
"Long before man existed, the land was regularly ploughed, and continues still to be ploughed by earthworms. 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 organized creatures." ”

“ And it must turn up many insect eggs and cocoons, to be eaten or to die. Earth worms is one sign of good soil. When the soil is naturally poor, or is worn out by bad farming, there will be few earthworms in it or none at all. (See Dragon-fly, Ichneumon Fly, Frog, Toad, Lady-bird, Earthworm.) ”

“ Earthworm populations will vary enormously according to climate and native soil fertility. Earthworms need moisture; few if any will be found in deserts. Highly mineralized soils that produce a lot of biomass will naturally have more worms than infertile soils lacking humus. Dr. Hopp surveyed worm populations in various farm soils. The table below shows what a gardener might expect to find in their own garden by contrasting samples from rich and poor soils. The data also suggest a guideline for how high worm populations might be usefully increased by adding organic matter. ”

“ How do earthworms reproduce? What care do they take of their young? What tissues or organs of earthworms correspond in function with the ectoderm of hydra; with the endoderm? Why does an earthworm need a system of blood circulation more than a hydra does? Contrast the number of openings in an earthworm's alimentary canal with the number in a hydra's digestive cavity. ”

“ In this particular case, which is on the whole the most emphatic of all the cases of peregrine earthworms, some explanations are possible, or at least have been offered. In the first place it would appear that earthworms are more abundant as individuals in northern countries where the soil is rarely dry for prolonged periods. And as has been already pointed out there is a close relation between earthworms and agriculture. Dunghills are fertile gathering grounds for some species, and ploughed fields and gardens always swarm with several species. ”

“ The way to increase worm populations is to increase organic matter, up mineral fertility, and eliminate acidity.
Earthworms and their beneficial activities are easily overlooked and left out of our contemplations on proper gardening technique. But understanding their breeding cycle allows gardeners to easily assist the worms efforts to multiply. In temperate climates, young earthworms hatch out in the fall when soil is cooling and moisture levels are high. As long as the soil is not too cold they feed actively and grow. By early spring these young worms are busily laying eggs. ”

“ And these are but a few of the evidences of the wonderful action of worms, collected by the activity of Charles Darwin and his sons.
Earthworms were not only scrutinised in their out-of-door work, but were kept in confinement and studied. It appears they swallow earth both to make their burrows and to extract all nutriment it may contain; they will eat almost anything they can get their skin over. From careful calculation it was shown that worms on an average pass ten tons of the soil on an acre of ground through their bodies every year. ”

“ It is well known that worms swallow earthy matter, and that having separated the nutritive portion, they eject at the mouth of their burrows the remainder in little intestine-shaped heaps. The worm being unable to swallow large particles, and as it would naturally avoid lime and other noxious matters, the fine earth beneath those things would by a slow but certain process be removed and thrown to the surface. The earthworm, moreover, requires moisture, and in dry weather finds it necessary to burrow beneath the parched surface ”

“ As the holes are partly filled by rains, the casts are most abundant after rains. The chief enemies of the earthworm are moles and birds. The worms work at night and retire so early in the morning that the very early bird has the advantage in catching worms. ”

“ One of these orifices, situated in the median dorsal line of the segment, appears always to be larger than the others, and penetrates directly to the perivisceral cavity. That these openings form a very ready and frequent means of escape to the colourless fluid may be ascertained by handling a large Earthworm, when some considerable quantity is nearly invariably found to escape from its dorsal surface. ”

“ Earthworms live underground in burrows that are sunk well below the frost line. In digging they work head downward, gnawing—although they have no hard jaws—and swallowing the earth that is not easily crowded aside and then throwing it out and perhaps heaping it up as "castings." The tunnel must be wide enough to let its occupant turn around in it, and it ends in a deep chamber in which one or more worms may pass the winter without freezing. These worms naturally seek a loose, damp soil, not only for ease of working, but because moisture is a necessity, as they breathe through their skin ”

“ It may be regarded as more probable that the earthworm inherits an instinctive tendency to draw down objects in special ways, and that this is subject to some modification under the play of experience, without the formation of anything so psychologically complex as a general notion, however rude. In any case the behaviour of earthworms in closing their burrows seems to afford indications of something more than instinct—of that profiting by the results of experience which characterizes intelligent procedure. ”

“ Inasmuch as in every case the Lumbricidae from non-European countries are identical with European species, since it has been shown that these animals are very readily introduced accidentally with plants, &c., and in view of the fact that they are impatient of sea water, it seems clear that the presence of these Lumbricidae in other continents is due to accidental transportation. Most earthworms live in the soil, which they devour as they burrow through it. ”