Unseen Tinny Terrors: Nematodes Are Everywhere!


Updated: 4 Feb 2024

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It’s great to see you guys! 

The organism we are going to discuss today in detail is a very interesting one. There are many amazing things about this creature that will make you think twice about it. 

What do you think it is?

That’s right – we’re shining a spotlight on nematodes (Latin: Nematoda). Nematodes and roundworms belong to the phylum Nematoda. Nematodes are also known as roundworms.

About 80-90% are nematodes present in the world. Nematodes are almost present everywhere you can imagine. They are most abundant in multicellular organisms.

Many captivating and informative facts are going through our minds right now, let us share our thoughts with you guys. Without any delay, let the exploration begin!

if all the matter in the world was swept away, leaving only nematodes, then ghostly, nematode-formed shapes would remain of every single thing. Oceans, humans, mites, trees… That’s how amazing and numerous they are. Nathan Cobb

Define Nematode

The organism that possesses the following characteristics can be considered a nematode:

  • Triploblastic
  • Bilateral symmetrical
  • Pseudocoleomate
  • Unsegmented body

Nematodes can live in all types of habitats. Marine beach sand may contain 1,500,000,000 nematodes per acre. A single wheat gall may contain 100,000 Anguina tritici juveniles. A single acre of soil from arable lands may contain 3,000,000,000 nematodes.

Almost 500,000 species are present in the world out of it only 25,000 species are discovered. This shows that the majority of nematode species are still not yet known.

Picture of attack by nematodes

Examples of nematodes in plants

Here are a few examples of nematodes that cause disease in plants:

  • Cyst nematodes
  • Lesions nematodes
  • Root-knot nematodes
  • Ring nematodes
  • Stubby-root nematodes
  • Spiral nematodes
  • Root-lesion nematodes
  • Sting nematodes
  • Dagger nematodes

Examples of nematode worms in humans

Here are a few examples of nematode worms present in humans:

  • Whipworms
  • Helminth
  • Filarial
  • Threadworm
  • Heartworm
  • Pinworms
  • Trichinella
  • Roundworms

Body Size

Nematodes vary in their body size. Freely living nematodes in freshwater and soil vary in size. Their length varies from 150 µm to 10 mm. There are species of nematodes that range from 83 µm50 mm in length. Some animal nematodes such as Dracunculus medinensis are much bigger.

Placentonea gigantissimum is the largest nematode having 8.5 m length and 0.5 m width. Greeffiela minutum is the smallest nematode with 82 µm in length. 

Plant parasitic nematodes vary from 0.25 mm-12 mm in length and the width of their body may range from 0.01-0.5 mm. Needle nematode Paralongidorus which is also the longest while Paratylenchus also called pin nematode is the smallest plant parasitic nematode.

Movement

The movement of plant parasitic nematodes in their free-living larval stage outside the host is very slow. They barely move one or two meters in a year. There are two types of movement in nematodes:

  1. Undulatory or serpentine movement
  2. Telescopic or earthworm-like movement

Undulatory movement

This movement is commonest in all nematodes except Criconemoides. In the undulatory movement contraction of muscles (waves) starts from the anterior to the posterior end. The length of the body does not change during the movement.

During the movement, one lateral side lies on the plane’s surface whereas the dorsal and ventral sides lie on the left or right sides.

Telescopic movement

This type of movement resembles the way an earthworm moves, involving both expansion and contraction of the body. This is commonly observed in Ogma and Criconema, which do not have lateral lines.

During this movement, the muscles contract starting from the posterior end and move towards the anterior end. As a result, the length of the body changes during the process.

Spread of Nematodes

There are three types of ranges through which nematodes are spread. These ranges also cover various means of spread. Ranges are as under:

  1. Short range spread
  2. Medium range spread
  3. Long range spread

Short Range Spread

In this type, nematodes are carried to short distances within a field. They are moved through the irrigation water and cultural practices in the field that disturb the soil also help in the spread of nematodes in the field.

Ploughing, hoeing, and harrowing can spread the nematodes from infested sites to nematode-free sites. Cyst and stem nematodes spread by this method.

Medium Range Spread

This spread is mostly by human activities. Movement of agricultural implements, transport vehicles, and feet of workers that can carry the soil from one field to another field. Planting of seedlings from infected nurseries is a major means of dispersal of nematodes.

Floods, dust storms, and strong winds are also means of nematode spread.

Long Range Spread

The introduction of nematodes in new areas often occurs through the transporting of planting materials such as seeds, tubers, and nursery stocks from one state to another state.

These nematodes include Globodera rostochiensis, Pratylenchus and, Tylenchulus semipenetrans. Many nematodes are carried inside the host parts such as Ditylenchus dipsaci in onion bulbs.

Survival and Longevity

The normal survival and longevity of nematodes in the presence and absence of the host are commonly short. The time of survival of some species in fallow soil is given below

Survival and Longevity
NematodesSurvival Time
Meliodogyne species6 – 16 months
Ditylenchus dipsaci1.5 – 2 years
Anguina tritici1 year
Globodera rostochiensis larvae9 months
Radopholus similis3 – 6 months
Aphelenchoides ritzemabosi12 – 17 weeks
Tylenchulus semipenetrans10 years
Globodera rostochiensis cysts7 years

9 Amazing Facts

Here are some facts about the nematodes that will add more information to your remarkable knowledge.

  1. Almost 500,000 species are present in the world out of it only 25,000 species have been discovered.
  2. Marine beach sand may contain 1,500,000,000 nematodes per acre.
  3. A single wheat gall may contain 100,000 Anguina tritici juveniles.
  4. A single acre of soil from arable lands may contain 3,000,000,000 nematodes.
  5. Placentonea gigantissimum is the largest nematode having 8.5 m length and 0.5 m width.
  6. Greeffiela minutum is the smallest nematode with 82 µm in length. 
  7. In the nitrogen cycle, nematodes are very essential. They also regulate the decomposition of organic matter.
  8. Did you know that for every human on Earth, there are more than 60 billion nematodes?
  9. 1 and 15% of the zoobenthic biomass in lakes is usually contributed by nematodes.

Conclusion

In this blog, we have discussed a unique definition of nematodes. Moreover, their sizes, movement, spread, and a few examples are shared to enhance your knowledge.

Additionally, some interesting facts about nematodes are enlisted that you might not have known before. These facts are collected from authentic sources. Nematodes are such an amazing topic, and we hope that you will find the information you are searching for.

We are always here at your service if you have any queries about our topics. Feel free to Contact Us.

FAQs about Nematodes

What are nematodes?

The organism that possesses the following characteristics can be considered a nematode:

  • Triploblastic
  • Bilateral symmetrical
  • Pseudocoleomate
  • Unsegmented body
Define nematode roundworm.

An unsegmented worm belonging to the phylum Nematoda; also called roundworm.

Write any three examples of nematodes.
  • Helminth
  • Filarial
  • Roundworms
What is the scientific name of roundworm?

 Ascaris lumbricoides

What is the definition of nematode Ascaris?

Ascaris is an intestinal parasite that commonly infects humans, representing the most common type of human worm infection.

Pseudocoelomate meaning

The organisms that are characterized by the presence of false body cavities are called pseudocoelomate.


Dr. M Awais

Dr. M Awais

This is Awais. I am a phyto doctor. I have studied plants my whole life. Plants are my best friends. I have gathered detailed information about plants. My brilliant team is always ready to accept the challenges. Together, we find the solutions for our clients.

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