# Abranchiata

CEFR C2 · Noun

Source: https://englishreference.com/word/abranchiata
Updated: 2026-08-15

## Definition

a very old scientific name for a group of simple, flat animals that live in the ocean. These animals have no heart or brain and are often called 'flatworms'.

For teachers: an obsolete taxonomic category for the class Turbellaria, consisting of simple, unsegmented flatworms. Historically used in biological classification systems before the adoption of modern phylogenetic nomenclature.

## Examples

- The scientist studied abranchiata to understand early animal evolution.
- In older textbooks, the flatworms were classified under the category of abranchiata due to their lack of circulatory and respiratory systems.
- While the term abranchiata is no longer used in contemporary biological taxonomy, it remains a significant historical marker for the study of primitive invertebrates and their evolutionary development.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.