Flatworm

Flatworms are a group of simple soft-bodied invertebrate animals that include the free-living planarians and the parasitic flukes and tapeworms. They are characterized by their flat, bilaterally symmetrical bodies and lack of a body cavity.

Classification

Flatworms belong to the phylum Platyhelminthes, which is divided into four classes: Turbellaria, Monogenea, Trematoda, and Cestoda. The class Turbellaria includes mainly free-living marine species, while the classes Monogenea, Trematoda (flukes), and Cestoda (tapeworms) are primarily parasitic.

Anatomy

Flatworms have a simple body structure with a head region, a tail region, and a central region that contains the organs. They lack a body cavity and their bodies are solid between the outer surface and the cavity of the digestive system. They have a simple nervous system with a pair of nerve cords running along the body and a brain at the front end.

Reproduction

Flatworms can reproduce both sexually and asexually. In sexual reproduction, most species are hermaphrodites, possessing both male and female reproductive organs. Asexual reproduction is common in many species, with individuals able to regenerate from fragments of their bodies.

Ecology

Flatworms are found in a wide range of habitats, from marine and freshwater environments to moist terrestrial environments. Many species are parasitic, living inside the bodies of other animals and causing diseases such as schistosomiasis and cysticercosis.

Medical Importance

Some flatworms are of significant medical importance as they are responsible for serious diseases in humans. The most notable are the blood flukes (Schistosoma) that cause schistosomiasis, and the tapeworms (Taenia) that cause cysticercosis and other diseases.

See Also

• Parasitology
• Invertebrates
• Zoology

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