I came across this in my collection of reading material and forgot that I had it. C. Elegans are often used in science for studying and experimentations. The below goes through their life-cycle -- you may find this interesting too. They can go 3 months without eating. If these tiny creatures can, I’m sure other nematodes can too. Imagine if someone had those as an infestation thinking that they could be starved out in a month’s time with a fasting/cleanse – not gonna happen!!

 DD

http://www.thewormbook.com

They Are Everywhere

C .Elegans is about the most unremarkable nematode known to man. There must be others, even less obvious, lurking undiscovered in the crannies of the world since nematodes are overwhelmingly the most numerous animals on earth. If a Martian biologist were to collect, at random, five million animals from the earth, sampling everything he could find, from apes and penguins through fish to the uncountable myriads of insects, almost all of them, four million, would be nematodes. The best estimates of the number of their species range between 100,000 and 10,000,000. The wild disparity of these estimates means that for every species we know about there may be a hundred that haven't been discovered yet, or there may be only ten. If Brenner had been interested in an organism that was economically valuable, he might have picked any of the numerous nematode parasites which cause humans suffering - either directly: about half the world's population are afflicted with parasitic nematodes, which can cause some extremely unpleasant diseases - or indirectly, because they parasitise almost everything that humans eat: not just sheep and cattle, but plants ranging from coffee to carrots. Victorian biologists catalogued nematode parasites of lions, vultures, and seal's kidneys, these last growing up to 40 inches long. There is a gruesome saying among worm researchers that if everything on earth were to disappear except the nematodes, the outline of all plants and animals would be left, filled out by their nematode parasites. Just how close this comes to literal truth emerges from the fact that there are three different species of nematode found living in the rectum of the American cockroach Periplaneta americana. There appears to be nowhere these animals will not try to live.

Yet elegans lives in tranquil obscurity underground, parasitising nothing, eating only bacteria and slime moulds.

The Teen Years

The greed of C. elegans, though effective in the short term, causes it long-term problems, because the animals will devour all the food available to them as quickly as possible. Nor are they well-adapted to long foraging voyages. The answer to these problems is supplied by the dauer state, which corresponds to the strange encystments practised by many parasitic nematodes. As soon as a worm is hatched, the growing, feeding first stage larva is sensitive to two chemicals in particular which it samples or smells through the bumps around its mouth. One is a pheromone produced by all worms, with extremely long-lasting effects. This means that a growing worm can smell pretty accurately how many worms are sharing her patch of bacteria. The second chemical that larvae are sniffing around them is the smell of food. If the smell of worm is stronger than the smell of food this sends a signal that there won't be much to keep an adult alive. The growing larva can distinguish between different strains of bacteria, and modifies its choice according to the nutritional value of the available food. Just what constitutes "stronger" is affected by temperature, too. The higher the temperature around a worm - they thrive best at around 20° — the more likely it is to turn towards dauer.

Normally developing larvae spend only seven hours in the second stage of their lives, and most of this time is spent growing their gonads and eggs. But a worm that senses too many other worms around it, and too little food, will spend nearly twice as long as a second-stage larva, and in this time it will lay up fat in the cells of its skin and intestine rather than developing eggs. When next it moults, to become a level three larva, the dauer is immediately recognisable for the outside. It is thinner and darker than a normal worm. Their stomachs have closed up: in fact the mouth is completely closed by a block of the cuticle that normally forms the worm's outer skin, and the pharynx is shrunken. Their skin acquires a protective, water-repellent coating. In this stage, they can survive for up to three months, waiting for food to reappear. They are passive, but not inactive. Think of them as sulky adolescents, conserving their energy for some grand adventure which may never come. They will move quickly if touched, and they seek out water: when left in petri dishes in the lab, they crawl at night into the droplets of condensation that form inside the lids and there form huddles. But mostly they just lie around the agar, waiting for fate, or food.

Voracity

Most of the life of a worm is spent eating, something at which it is fantastically efficient. Fifty per cent of the weight of bacteria it eats is converted to worm tissue, and its mechanisms for doing so are brutally efficient. The mouth cavity of elegans, seen under a scanning electron microscope, has six diamond-shaped bumps around it that compress the opening into something shaped like a star of David. There is a photograph showing this head, full of vast and formless menace at 8400x magnification, with a few hapless bacteria dangling from the lips. The sensory bumps or studs surrounding the mouth have tiny channels in them, which the nematode uses to smell the world around it, and to detect the chemicals release by other worms.

As an invertebrate, elegans has no jaws or teeth. Instead it has a pharynx, a short, muscular tube with a round bulb or crushing chamber at the far end. Each section of the pharynx lies between three muscles running along its length. At rest, these muscles relax, constricting the tube between them into three folds like a Mercedes emblem in cross-section. When they contract, the sides of the pharynx spring apart to make a triangular tube, into which any liquid in front of the worm is sucked. When the muscles relax again, the liquid is expelled but any food particles it contains are trapped within the pharynx. It's odd to reflect that this is essentially the same method of feeding used by the largest animals on the planet, blue whales, who also suck their food in as liquid and then strain out the good bits. Whales, however, have visible strainers for their food. The worm has no strainers visible, even in an electron microscope. The separation may be accomplished by some exquisitely tuned turbulence in the liquid as it's pumped through this channel much thinner than a human hair.

From the worm's pharynx, the filtered-out bacteria move backwards to the grinding bulb at the end, lined with knobbly projections which crush open the bacteria, so their nutrients pass backwards into the gut, propelled at high pressure by the pumping muscles of the pharynx. The interior of the worm is pressurised: if you prick one it does not bleed but it will burst. This means that it needs no muscles in the intestine. All it needs to do it relax the muscle closing off the other end and everything left from digestion is expelled at the anus: the healthy worm defecates about every 45 seconds all its life.

Sex Life

The most important thing about C. elegans at the beginning, apart from the fact that it could be displayed under an electron microscope in illuminating ways, was its sex life. It has sex early and often, usually with itself. These two facts make it fascinating for geneticists. C. elegans takes less than four days to grow from an egg to an egg-laying animal so the results of an experiment are quick to appear. The sex organs of a hermaphrodite C. elegans take up most of the middle of its body., they resemble an art nouveau "y" that has been squashed flat, so that the very short stalk is the vulva, and the two long arms, each folded back once on itself in a hairpin bend, are the gonads, where eggs and sperm develop. The eggs start to develop at the far point of the hairpin, and gradually grow as they move around the bend in the tube towards the vulva. The sperm, which are repulsive to look at , lurk at the exit of this tube, and fertilise the eggs before they move into the vulva. Unlike most animal sperm, those of nematodes have no tail and don't wiggle or swim; instead, they are amoeboid blobs, that drag themselves along a surface by expanding and contracting the cell walls like tiny caterpillar tracks.

Once fertilised, the embryo develops inside the eggs until it has grown to a tiny larva, which hatches once the eggs have been expelled form the vulva. Since the worm and its eggs are transparent, this process can actually be watched through a microscope as it happens

The mathematics of worm sex are simply mind boggling. I once tried to work out how many worms had laid down their lives for science in the last thirty years, and decided very rapidly that the number was incalculable. I mean that quite literally, and not just because my spreadsheet refused to contemplate them. The beginning of the calculation is quite easy to make: a worm will grow to maturity in about three and a half days. After that it will start laying eggs. Most will lay about 300 eggs in over the next four days; each of these will hatch in four days' time into a hermaphrodite that will lay another 300 eggs. So one worm has three hundred children and 90,000 grandchildren. These 90,000 worms would, if food were unlimited, produce 27 million children of their own. By the end of a month, assuming unlimited food and room, one worm could have eight thousand million living progeny, or, as an American would say, eight billion. There aren't that many people alive on earth. After the second month , each of those eight billion worms could have produced another eight billion descendants giving as the total number of possible descendants of one hermaphrodite in 69 days a figure that has 27 zeros after it. No wonder the spreadsheet boggled. When God promised Abraham descendants who would outnumber the stars in the sky or the grains of sand on a beach, he didn't mention that he had made the same promise to a worm first.