Difference between Worms and Parasites


They are slender, cylindrical animals that typically include annelids, platyhelminths, nematodes and some insect larvae.

  • Annelids are segmented worms or ringed worms. Example – Earthworm.
  • Platyhelminths are flat, ribbon-like worms that have an unsegmented, soft body. Example – Tapeworms and flatworms.
  • Nematoda constitutes thread-like hookworms and roundworms.

When a human or animal is said to have been infested with worms, it usually denotes the parasitic worms. Typically, tapeworms and roundworms are the common parasitic worms. The term ‘worm’ is also sometimes used to refer to millipedes, centipedes, amphibian caecilians, and blindworms (legless lizards).


Parasites are organisms that live in close relationships with other organisms (hosts) for their survival. They can possibly cause damage to their hosts. They include protozoans, hookworms, fungi, lice, etc. Some can be directly transmitted to the host via contact, while some are transmitted through food. Parasites can also be transmitted through vectors. Example – Mosquito transmits Plasmodium (obligate parasite) and causes malaria.

An obligate parasite completes its whole life cycle inside the host. Whereas facultative parasites can complete their life cycle even without the host. Likewise, parasites can be classified into two types based on their habitat.

  • Ectoparasites – They live on their host. Example – Leech
  • Endoparasites – They live inside their host. Example – Roundworms.

Also Read: Parasites and Symbiosis – Relation and Diseases

Difference between Worms and Parasites



They are slender, cylindrical animals that may or may not depend on a host for survival.

They are organisms that depend on their host for survival. Also, they can probably cause damage to their host.

Some worms are parasites.

Not all parasites are worms.

Worms include annelids, platyhelminths, nematodes and some insect larvae.

Parasites include protozoans, fungi, helminths, arthropods, etc.

Explore: Difference between Host and Parasite

Frequently Asked Questions on


What are parasitic worms?

They are helminths that mostly include intestinal worms. These parasites colonise the intestinal tract. Example – Tapeworm. Some parasitic worms also reside and infest blood vessels. Example – Blood fluke. Also, there are ectoparasitic worms like leeches (annelids) that live on the host.


What are parasitoids?

It is an organism that lives at the expense of its host. These parasites will eventually lead to the death of the host organism. Some worms, wasps, flies and beetles can be parasitoids. Their host interaction is highly specific.


Is ringworm a type of worm?

Ringworm is a type of fungal skin infection. The term does not refer to an actual ‘worm’. Parasitic varieties of fungus such as Microsporum cause this skin infection. It results in a circular, red, itchy rash.

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