Main difference – Flatworms vs Roundworms

Flatworms and also roundworms room two varieties of worms with many differences in your body. Flatworms belong to the phylum Platyhelminthes if roundworms belong come the phylum Nematoda. The main difference in between flatworms and also roundworms is the flatworms consist of a dorso-ventrally flattened human body whereas roundworms consist of a cylindrical human body tapered to a fine suggest at every end.  Both roundworms and tapeworms space triploblastic animals with bilateral symmetry. They room protostomes, exhibiting the spiral, determinate cleavage.

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Key locations Covered

1. What is a Flatworm – Definition, body structure, Pathology 2. What is a Roundworms – Definition, body Structure, Pathology 3. What space the Similarities in between Flatworm and Roundworm – rundown of common Features 4. What is the Difference between Flatworm and also Roundworm – compare of an essential Difference

Key Terms: Cestoda, Flatworm, minister Parasites, Nematoda, Platyhelminthes, Roundworm, suck Mouthparts


What space Flatworms

Flatworms describe a phylum the invertebrates, comprising of a dorso-ventrally planarization body. Around 20,000 flatworm varieties can be discovered on earth. Most flatworms space parasitic. Some space free-living in seawater or fresh water. Flatworms room triploblastic pets with bilateral symmetry. Their body is dorso-ventrally flattened. They space acoelomates because they lack a body cavity. Flatworms have an incomplete digestive system. They additionally have a gastrovascular cavity, which serves as the stomach. A solitary opening serves together both mouth and also anus. A flatworm is presented in figure 1.


Figure 1: A Flatworm

Respiration that flatworms occurs by straightforward diffusion v the human body surface. The excretory mechanism of flatworms consists of protonephridia v Flame cells. The gliding kind locomotion of flatworms occurs through cilia. Asexual reproduction of flatworms occurs either by rejuvenation or fission. Flatworms room hermaphrodites with internal fertilization. Turbellaria, Trematoda, and also Cestoda space the three classes that flatworms.

What space Roundworms

Roundworms describe a phylum that invertebrates through cylindrical bodies. About 15,000 types of roundworms have been determined in the world. Due to the fact that roundworms covers a full-fledged body cavity, they room classified together pseudocoelomates. Roundworms covers a tough outer covering referred to as cuticle in your epidermis. The body surface of roundworms consists of ridges, warts, and also rings. The head the the roundworms own sensory bristles and also solid shields. Roundworms covers a complete digestive system. The mouth is composed of a sharp stylet supplied for sucking liquid. The thrashing movement of roundworms occurs with longitudinal muscles. A roundworm is shown in figure 2.


Figure 2: A Roundworm

Roundworms covers a life bike with seven stages: egg, 4 larval stages, and two adult stages. Part nematodes room hermaphrodites, and others space dioecious. Hermaphrodites reproduce through self-fertilization. Different male and female individuals reproduce through copulation. Filaria worms (cause elephantiasis), Ascaris (cause ascariasis), hookworms (infestation because that a long time reasons anemia and also helminthiasis), Trichinella (cause trichinosis), and pinworms (infest the huge intestine) are examples of roundworms.

Similarities in between Flatworms and also Roundworms

Both flatworms and also roundworms belong to the kingdom Animalia.Some flatworms and roundworms space free-living, and also some space parasitic.Both flatworms and also roundworms room unsegmented worms.Both flatworms and roundworms space multicellular, mobile, invertebrate animals.Both flatworms and roundworms space heterotrophs.Both flatworms and also roundworms show bilateral symmetry.Both flatworms and also roundworms display organ level organization.Both flatworms and also roundworms space triploblastic animals.Both flatworms and roundworms space protostomes.Both flatworms and also roundworms present spiral, determinate cleavage.

Difference between Flatworms and also Roundworms


Flatworms: Flatworms refers to a phylum that invertebrates, consisting of of a dorso-ventrally planarization body.

Roundworms: Roundworms refers to a phylum of invertebrates through cylindrical bodies.


Flatworms: Flatworms belong to the phylum Platyhelminthes.

Roundworms: Roundworms belong to the phylum Nematoda.


Flatworms: Turbellaria, Trematoda, and Cestoda room the three classes of Platyhelminthes.

Roundworms: Roundworms and Secernentea are the two classes of Nematoda.


Flatworms: Flatworms are acoelomate animals.

Roundworms: Roundworms space pseudocoelomate animals.

Type that Protostomes

Flatworms: Flatworms belong to the superfamily Lophotrochozoa.

Roundworms: Roundworms belong come the superfamily Ecdysozoa.


Flatworms: The dimension of the tapeworm might vary from 1 mm to 15 m.

Roundworms: Roundworm in humans may grow up come 35 cm.

Body Structure

Flatworms: Flatworms consist of a level body.

Roundworms: Roundworms covers a cylindrical body tapered come a fine allude at every end.

Outer Covering

Flatworms: Flatworms lack a cuticle. The human body of Platyhelminthes often has cilia.

Roundworms: Roundworms consists a difficult outer covering dubbed cuticle.

Digestive System

Flatworms: Flatworms consists an incomplete digestive system.

Roundworms: Roundworms covers a finish digestive system.


Flatworms: Flatworms exhibit a thrashing motion.

Roundworms: Roundworms exhibition a gliding locomotion.


Flatworms: Flatworms room unisexual pets that reproduce with copulation.

Roundworms: Roundworms room hermaphrodites that reproduce with cross-fertilization.


Flatworms: Flatworms space transmitted by spend infected fleas.

Roundworms: Roundworm deserve to be transmitted through infected fecal issue or consuming pet tissue with worm larva.

Lives in

Flatworms: Flatworms live in the intestine.

Roundworms: Roundworms live in the small intestine.


Flatworms: Flatworm segments deserve to be identified in the feces. Diarrhea and also vomiting may take place in large infections.

Roundworms: Roundworms deserve to be diagnosed by the fecal flotation exam. Adult roundworms might reveal with the vomit.


Flatworms: Flatworm infections may reason weight loss and tiredness.

Roundworms: Roundworm might cause huge infections in lungs.


Flatworms: Schistosomiasis, lung flukes, and liver flukes are the conditions caused by flatworms. 

Roundworms: Ascariasis, hookworm disease, and trichuriasis are the diseases caused by roundworms.


Flatworms and also roundworms room two species of worms the live either complimentary in the environment or live as helminth in the intestine the animals. Flatworms belong to the phylum Platyhelminthes. They consist of a dorso-ventrally planarization body. Roundworms belong come the phylum Nematoda. They consist of a cylindrical body. Thus, the key difference between flatworms and also roundworm is the framework of the body of each form of worm.

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1. Smyth, James Desmond. “Flatworm.” Encyclopædia Britannica, inc., 6 Feb. 2014, obtainable here. 2. Introduction to the Platyhelminthes, obtainable here. 3. “Roundworms.” college of Maryland clinical Center, accessible here. 4. “Roundworm.” NHS Choices, NHS, accessible here.

Image Courtesy:

1. “Hookworm filariform A” through Fernandolive – Own occupational (Public Domain) via Commons Wikimedia 2. “New new zealand flatworm” by S. Rae (CC by 2.0) via Flickr