Neorhabdocoela

flatworm order

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

July 13, 2026

Quick Summary

The Neorhabdocoela are an order within the class Turbellaria, which are a type of flatworm. These flatworms are characterized by a simple, unbranched intestine and are found in marine, freshwater, or occasionally terrestrial environments. They are typically small and possess a saclike linear intestine. Members of this order usually have protonephridia and oviducts, with a few, mostly compact gonads. The nervous system generally consists of two longitudinal nerve trunks. Flatworms, as a phylum (Platyhelminthes), are soft-bodied invertebrates, with about 80% being parasitic. They lack specialized respiratory, skeletal, and circulatory systems, and have no body cavity.123

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

3 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

flatworm
Annotated classification
Order Neorhabdocoela Saclike linear intestine; protonephridia and oviducts usually present; gonads few, mostly compact; nervous system generally with 2 longitudinal trunks; about 600 species. Order Catenulida Mostly freshwater; about 70 species. Order Macrostomida Mostly inhabiting the areas between grains of sand;
Read More
Order Neorhabdocoela Saclike linear intestine; protonephridia and oviducts usually present; gonads few, mostly compact; nervous system generally with 2 longitudinal trunks; about 600 species. Order Catenulida Mostly freshwater; about 70 species. Order Macrostomida Mostly inhabiting the areas between grains of sand;
Read More