We recently received a picture of a worm (posted below) that was discovered by a reader who was wondering what type of worm she found. The worm was found in a puddle in Indiana, where the reader is from (that is, the reader is from Indiana, not the puddle, presumably). We have long awaited a simple question to answer, as we’ve been dealing with some difficult (and strange) questions as of late, and happily this particular reader’s question is within our ability to identify. We are very confident that our reader found a horsehair worm (sometimes known as “Gordian worms”), which is a nematode or roundworm (also spelled “round worm”).
Roundworms, also known as nematodes (and sometimes incorrectly spelled “round worms”), are one of the most diverse animals in the world. Over 28,000 roundworm species have been discovered, well over half of which are parasitic. The present accounting of roundworms is no where near complete, however, as it has been estimated that there are over 1,000,000 species of roundworms on the planet. That is 1,000,000 different species of roundworms, not just the number, of course, of roundworms on the planet in general, which is surely larger by several orders of magnitude. Some people confuse roundworms, and ringworm, probably because ’round’ and ‘ring’ seem similar, however ringworm, which is not actually a worm at all, is something completely different.