Roundworms, of the Phylum Nematoda

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.

With such a staggering number of different species of roundworms, it is not surprising that the various kinds are often hard to distinguish from one another. (Imagine trying to conceptualize a million different animals that are sufficiently similar to part of the same phylum, yet different enough to be classified as a separate species.) Presumably, the similarities between species makes the process of cataloging all the different roundworms, a truly monumental undertaking, all the more challenging.

UPDATE! All About Worms has partnered with HealthLabs so that
you can get tested for parasites at a fully-qualified lab near you,
no doctor's visit required
! Check it out at HealthLabs.com!

Given their diversity, roundworms have adapted to almost all ecosystems. You can find roundworms in a tropical ocean, a desert, the arctic, and everywhere in between, including high and low elevations. They are omnipresent in bodies of water, where their count often far outnumbers any other animal present. As a case in point, roundworms account for 90% of all life forms found on the ocean floor.

Roundworms tend to be small, with lengths under 2.5 millimeters, and this makes sense – if they were significantly larger, the astronomical number of worms would cover the entire world. Even the largest roundworms are customarily only about five centimeters long, although some of the parasitic species sometimes grow a little longer. The smallest species, in contrast, are microscopic. Although their appearances vary widely, roundworms often have distinctive features like rings or ridges around their bodies.

Although thousands of species of roundworms live in nature performing vital ecological roles, like the recycling of certain nutrients in ocean environments, many people think of roundworms as parasites, and rightfully so. Roundworms are responsible for causing all sorts of problems with pets, especially cats and dogs, whose small intestines serve as an inviting habitat to certain types of roundworms. Moreover, once a pet is infected, it can spread the worms to the other pets around it, chiefly because roundworms may produce millions of eggs a day that can be passed into the environment.

No Paywall Here!
All About Worms is and always has been a free resource. We don't hide our articles behind a paywall, or make you give us your email address, or restrict the number of articles you can read in a month if you don't give us money. That said, it does cost us money to pay our research authors, and to run and maintain the site, so if something you read here was helpful or useful, won't you consider donating something to help keep All About Worms free?
Click for amount options
Other Amount:
What info did we provide for you today?:

Humans can also be afflicted with roundworms, normally by way of ingesting infective eggs. If infected, the larvae can travel through a person’s tissues, like his or her liver or brain, which can cause inflammation or mechanical damage to organs. Roundworms can even cause blindness when their larvae migrate through a person’s eyes, a tragedy to which children are more susceptible than are adults.

Roundworms are all over the world in prodigious numbers. Some are parasitic, causing problems to their hosts, others play a key part in their habitat, helping maintain the health of the environment. Since a million different species of roundworms are believed to exist, this is hardly surprising.

1 Comment

  1. Linda valdez

    I have a simular problem for the past three nights there have been hundreds of paracitic wormcovring my porch a walls they are long, black , lots of little feet but move like an inch worm only faster when stepped on they turn to liquid please help,

Leave a Comment (but to submit a question please use the "Submit a Question" link above; we can't respond to questions posted as a comment)

Menu / Search

All About Worms