Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos
Orbiniida
References
Britannica AI Icon

Orbiniida

polychaete order
Written by
The Information Architects of Encyclopaedia Britannica

The Information Architects maintain a master list of the topics included in the corpus of  Encyclopædia Britannica, and create and manage the relationships between them.
The Information Architects of Encyclopaedia Britannica
Last updated

Quick Summary

The Orbiniida are a sedentary order within the class Polychaeta, which are marine worms belonging to the phylum Annelida. Polychaetes are characterized by well-defined body segmentation and, uniquely among annelids, most possess parapodia with setae (bristles) on each body segment.1

Orbiniida are distinguished by a pointed or rounded head without appendages and an eversible, unarmed proboscis. Their bodies are divided into a distinct thorax and abdomen, with gills arising dorsally from the thoracic region. These worms can range in size from minute to approximately 40 cm. Notable genera within this order include Scoloplos and Paraonis.2

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
2 Britannica Sources
  1. polychaete
  2. annelid - Annotated classification

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.