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...

Neurology of Illusions
Neurology of Illusions

Illusions are the perceptions and sensory data obtained from situations in which human error prevents us from seeing the..

Genetics and Evolution
Genetics and Evolution

Humans are diploid creatures. This means that for every chromosome in the body, there is another one to match it. Howeve..

Sugar Homeostasis
Sugar Homeostasis

The blood sugar level is regulated by two hormones. The mechanism behind this type of negative feedback control is descr..

Salmon jumping upstream in the river
Lotic Communities & Animals

A running water environment offers numerous microhabitats for many types of animals. Similar to plants, animals in lotic..

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..

New Zealand Fauna
New Zealand’s Unique Fauna

Meet some of New Zealand's unique fauna, including endemic insects, frogs, reptiles, birds, and mammals, and investigate..