Dictionary > Flatworm

Flatworm

Definition
noun, plural: flatworms
Any of the worms (e.g. tapeworms, trematodes, planarians, etc.) belonging to the phylum Platyhelminthes, characterized by a flattened and bilaterally symmetrical body
Supplement
The flatworms make up the phylum Platyhelminthes (i.e. etymologically, platy meaning flat and helminth meaning worm) that are distinguished by their flat and bilaterally symmetrical body. Some of them are free-living whereas others are parasitic. The phylum is divided into four groups: (1) turbellarians, (2) trematodes, (3) monogeneans, and (4) cestodes. Turbellarians are mostly free-living. Most of them are scavengers and predators. Their length ranges from 1 mm to 600 mm. Pseudoceros dimidiatus is an example of a turbellarian. Trematodes include the groups Digenea and Aspidogastrea. They are distinguished by their holdfasts resembling suckers that aid them to anchor within the host. Monogeneans are mostly ectoparasites of fish, amphibians, and aquatic reptiles. They have haptors, which are attachment organs they use to attach to their host. Cestodes are parasitic tapeworms. Taenia solium (pork tapeworm), Taenia saginata (beef tapeworm), and Diphyllobothrium spp. (fish tapeworm) are some of the tapeworms that can infest humans.
The flatworms are unsegmented, soft-bodied invertebrates. They do not have specialized circulatory and respiratory organs and therefore rely on diffusion to move oxygen and nutrients through their bodies. They have an incomplete digestive system. There is only one opening where food enters and where the non-digested particle leaves.
Scientific classification:

  • Kingdom: Animalia
  • Phylum: Platyhelminthes

Variant(s):

  • flat worm

See also:


You will also like...

Sensory systems
Sensory Systems

A sensory system is a part of the nervous system consisting of sensory receptors that receive stimuli from the internal ..

Schematic diagram of DNA replication
DNA Structure & DNA Replication

DNA is a double helix structure comprised of nucleotides. A nucleotide, in turn, is made up of phosphate molecule, deoxy..

Early Mammals on Earth
Early Mammals on Earth

The Earth's ecosphere was rapidly changing and throwing up a wide range of ecological niches that new adaptive organisms..

Buttress roots
Roots

This study guide tackles plant roots in greater detail. It delves into the development of plant roots, the root structur..

Gene Pool and Speciation
The Gene Pool and Population Genetics

According to Charles Darwin's theory of natural selection, preferable genes are favored by nature in the gene pool, and ..

Peppered moth ("Biston betularia") melanic and light form
Examples of Natural Selection

Darwin's Finches are an example of natural selection in action. They are an excellent example of the way species' gene p..

Related Articles...

No related articles found

See all Related Topics