The key difference between planarians and tapeworms is that planarians are unsegmented free-living flatworms of the class turbellaria that live on freshwater. Meanwhile, tapeworms are segmented parasitic flatworms of the class Cestoda which reside on the intestines of animals including humans.
Platyhelminthes is a phylum which consists of thin, soft worms, possessing the shape of a leaf or ribbon-like structure. Platyhelminthes are also known as flatworms. They are found in the family planaria and live in ponds while parasitic types such as flukes and tapeworms are found in animal bodies and humans. The phylum Platyhelminthes consist of three different classes: Turbellaria, Cestoda and Trematoda. Class turbellaria is composed of many free-living organisms, while some are parasitic. Trematodes are commonly known as flukes. They are parasitic flatworms with an unsegmented body. Tapeworms are referred to as cestodes. They have a segmented ribbon-like body, and they are parasitic.
CONTENTS
1. Overview and Key Difference
2. What are Planarians
3. What are Tapeworms
4. Similarities Between Planarians and Tapeworms
5. Side by Side Comparison – Planarians vs Tapeworms in Tabular Form
6. Summary
What are Planarians?
Planaria are a type of flatworms belonging to class turbellaria of phylum Platyhelminthes. They have elongated, soft and leaf-shaped bodies, with a 0.2-inch length. However, the largest species may reach a length of 0.5 m. Their head is spade-shaped and has two eyes. Sometimes, there are tentacles on it. Moreover, they have a pointed tail. Most of them are free-living and found mainly in freshwater bodies. However, there are several terrestrial and marine species as well.
Figure 01: Planaria
Planaria show a special ability of regeneration. It is the mode of asexual reproduction seen in planarians. In contrast, sexual planaria are hermaphrodites possessing both male and female sexual organs.
What are Tapeworms?
Tapeworms belong to the class Cestoda. They are long, slender and elongated organisms which vary in length from 2mm to 10m. They consist of a segmented body, and the segments are referred to as proglottids. The main segments of the tapeworms are termed as the scolex, neck and strobila. The scolex is the head, and the strobila gives rise to new proglottids from the neck region. Their reproductive systems are not well developed but contain a prominent uterus, where the eggs are embedded.
The tapeworms do not possess an alimentary canal. As they reside on the small intestines, they are capable of taking nutrient components across the tegument. The excretory cell type is a flame cell, which consists of a ciliary network.
Figure 02: Tapeworms
Tapeworms are hermaphroditic, and each proglottid contains female and male reproductive organs. The eggs are formed into a larval stage known as the plerocercoid larva, and they develop into mature tapeworms inside the host system.
The tapeworm infection is also a common infection of the gastrointestinal system. Many different tapeworm species are involved in the onset of the infection, including Taenia saginata, Taenia solium and Diphyllobothrium latum. They are mostly present in partially cooked or undercooked meat and fish. The symptoms of the tapeworm infection include nausea, fatigue, weight loss and nutrient deficiencies.
What are the Similarities Between Planarians and Tapeworms?
- Planarian and tapeworms are flatworms belonging to phylum Platyhelminthes.
- They are soft-bodied invertebrates that are bilaterally symmetrical.
- Moreover, they are acoelomates.
- They lack specialized respiratory, skeletal, and circulatory systems.
What is the Difference Between Planarians and Tapeworms?
Planarians are flatworms belonging to class turbellaria of phylum Platyhelminthes and are mostly free-living. Meanwhile, tapeworms are flatworms belonging to class Cestoda of phylum Platyhelminthes and are parasitic and live in the intestine of animals and humans. So, this is the key difference between planarians and tapeworms.
Moreover, planarians are found in freshwater, especially in the pond water, while tapeworms are found on the intestines of animals. Besides, structurally, planarians are unsegmented worms while tapeworms are segmented worms. Therefore, this is also a difference between planarians and tapeworms.
Summary – Planarians vs Tapeworms
Planarians and tapeworms are two types of flatworms that belong to phylum Platyhelminthes. Planarians are unsegmented flatworms, which are free living. They belong to class turbellaria. On the other hand, tapeworms are segmented flatworms which are parasitic and live in the intestines of animals. They belong to class Cestoda. So, this is the summary of the difference between planarians and tapeworms.
Reference:
1. “Planarian.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 19 Mar. 2019, Available here.
2. “Reproduction of Planaria Worms.” Study.com, Available here.
Image Courtesy:
1. “Polycelis felina” By Eduard Solà – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Taenia saginata adult 5260 lores” (Public Domain) via Commons Wikimedia
