Nematology in the ancient times
Nematodes are small worms. The name nematode comes from the Greek word ‘nema’ that means ‘thread’. The soil inhabiting species are usually 1 mm long, but marine nematodes can reach lengths of over 5 cm, whereas animal parasites can vary from 10 to 30, 40 centimetre.
After Borellus in 1656 had observed "little snakes" in vinegar, he though he found an explanation for the acid taste of vinegar: the little snakes had pointy tongues. It took until 1742 before Baker broke this widespread myth. The nematode species Anguino tritici (a common parasite in wheat) is probably even mentioned by Shakespeare in his 1549 play 'Love’s Labour’s List' when he writes about 'sowed cockle, reaped no corn' describing the seed-galls in wheat plants.
Parasitic nematodes were already known in ancient Egypt. The 'Papyrus Ebers' dating back to 1500 BC contains accounts about roundworms and guinea worms. The latter is an 80 cm long nematode that prefers to live under human skin. Ancient Egyptians used a technique still used today: after a careful incision is made in the skin, the nematode is pulled out gently by winding it on a stick. This bares a striking resemblance to the 'Rod of Asclepius' sign still used by medical doctors!
Nowadays we look upon nematodes as a very successful class of animals. Four out of five multi-cellular animals on earth are nematodes. They're present almost everywhere: in cultivated fields, in sand dunes, in the sediments beneath the Ocean floor, in groundwater, in plants, animals and even in humans. Where there's organic material that can be decomposed, nematodes are present. A handful of dirt contains at least 50 different species of nematodes.
The nematologist Cobb wrote in 1914: "Nematodes are extremely widespread, and to be found in most unexpected places; they are also inconceivably abundant. A thimbleful of mud from the bottom of river or ocean may contain hundreds of specimens. The nematodes from a 10 - acre field, if arranged single file, would form a procession long enough to reach around the world.
If all the matter in the universe except the nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes and oceans represented by a film of nematodes.The location of towns would be decipherable, since for every massing of human beings there would be a corresponding massing of certain nematodes."
Now we can add that we can also indicate the areas where a modern farmer should not grow certain crops, and where the soil needs a clean up sanitation. The number of nematodes per square metre varies from 2 to 10 million. It is estimated that 80% of all multicellular animals on earth are nematodes. Some nematodes are highly specific with respect to their food source. Potato cyst nematodes, for example, feed on potato only. Other plant parasitic nematodes feed on almost every plant species in the field. Apart from plant parasitic nematodes, there are also nematodes feeding on fungi, algae, bacteria, insects, or smaller nematodes. Remarkably, in more or less inactive stages, nematodes withstand freezing and desiccation rather well. When the environment becomes favourable again, they resume their activities.