Platyhelminthes (from Ancient Greek πλατύ (platy) 'flat' and ἕλμινς (helmins) 'parasitic worm') [4] is a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrates commonly called flatworms or flat worms. Being acoelomates (having no body cavity), and having no specialised circulatory and respiratory organs, they are restricted to having flattened shapes that ... Flatworms are the simplest of the worm groups.

Understanding the Context

There are about 20,000 species in this group. Flatworms are found many places and can be free living or parasitic. A parasite lives off another living thing called a host and can be harmful. One of the best known flatworms is the tapeworm.

Key Insights

The tapeworm can get into a persons digestive tract and grow to enormous lengths. The tapeworm then eats off ... Description A flatworm's soft body is ribbon-shaped, flattened dorso-ventrally (from top to bottom), and bilaterally symmetric. They are the simplest triploblastic animals with organs. This means their organ systems form out of three germ layers: An outer ectoderm and an inner endoderm, with a mesoderm between them.

Final Thoughts

Turbellarians generally have a ciliated epidermis, while cestodes and ... Flatworm, any of the phylum Platyhelminthes, a group of soft-bodied, usually much flattened invertebrates. Several species are free-living, but about 80 percent are parasitic. They are bilaterally symmetrical and lack specialized respiratory, skeletal, and circulatory systems; no body cavity (coelom) is present. The humble planarian flatworm can regrow its brain. Here’s how this tiny animal will have you rethinking everything you thought you knew about memory.

Meet The Flatworm That Refuses To Die. Hint: It Can Regrow Its Brain ... The term "worm" has been applied to thousands of diverse, unrelated invertebrate animals, including snakelike lizards called blindworms. However, for common usage, worm is a name generally given to elongated, soft and limbless animals such as flatworms and roundworms.