How diverse are nematodes?
Nematodes may well be the most diverse group of multicellular animals. Unfortunately, most text books haven’t got a clue, so repeat this sentence three times before you read on: PERHAPS THE MOST DIVERSE GROUP OF ANIMALS (x3). No one knows even approximately how many species of nematodes currently exist on earth, but published figures range from less than 100,000 to 100 million – a difference of three orders of magnitude. The 100 Megaspecies estimate has given rise to the somewhat dubious statement that “four out of every five animals is a worm, and the fifth is a beetle”. In reality, there is as yet no reliable way of estimating the total number of living insect species, and much less so the numbers of species of nematodes, fungi, mites, protozoans, bacteria, etc., etc. All we really know is that the estimated numbers for all these “creepy-crawlies” continue to increase drastically, as we assess more and more of their genetic diversity, rather than just their poorly visible morphology
