Annelida

Also known as annelid, annelids, segmented worms, segmented worm

The annelids (), also known as the segmented worms, are animals that comprise the phylum Annelida (; ). The phylum contains over 22,000 extant species, including ragworms, earthworms, and leeches. The species exist in and have adapted to various ecologies – some in marine environments as distinct as tidal zones and hydrothermal vents, others in fresh water, and yet others in moist terrestrial environments.

OverviewAI-generated

Annelida is a phylum within the kingdom Animalia, commonly referred to as annelids. The taxon was described by Lamarck in 1802 under the name Annelides and currently holds an accepted status. This group of organisms has existed since approximately 530 million years ago, with a start time recorded at about 516 million years ago. Annelids inhabit marine, brackish, and freshwater environments.

Specimens of this phylum are held by institutions including SDNHM, LACM, UWBM, and USNM, primarily in the United States and Canada. These collections contain 8,956 records and 479 media items. Broader occurrence data indicates 9,907,382 recorded instances, while scientific literature includes 17,405 relevant publications. The taxon is referenced by 2,117 other encyclopedia articles.

Synthesized by Vinony from 25 facts across 7 sources: Wikidata, GBIF, PubMed, Gbif Occ, WoRMS, iDigBio, Vinony graph. Generated from structured data (not the Wikipedia text) and checked against those facts — may still contain errors.

Species

annelids

Annelida

PHYLUM

KingdomAnimalia
PhylumAnnelida

Habitatmarine, brackish, freshwater

Observations recorded9,907,382

via GBIF

Museum specimens

Specimen records: 8,956
With media: 479
Collections: SDNHM, LACM, UWBM, USNM
Recorded in: United States, Canada

iDigBio →

Research

17,405 papers

via PubMed

~44 min read

Encyclopedic overview

21 sections

Contents

Classification and diversity
Distinguishing features
Description
Segmentation
Body wall, chaetae and parapodia
Nervous system and senses
Coelom, locomotion and circulatory system
Respiration
Feeding and excretion
Reproduction and life cycle
Asexual reproduction
Sexual reproduction
Ecological significance
Interaction with humans
Evolutionary history
Fossil record
Internal relationships
External relationships
Notes
References
External links

The annelids are bilaterally symmetrical, triploblastic, coelomate, invertebrate organisms. They also have parapodia for locomotion. Most textbooks still use the traditional division into Polychaetes (almost all marine), Oligochaetes (which include earthworms) and Hirudinea (leech-like species). Cladistic research since 1997 has radically changed this scheme, viewing leeches as a sub-group of oligochaetes and oligochaetes as a sub-group of polychaetes. In addition, the Pogonophora, Echiura and Sipuncula, previously regarded as separate phyla, are now regarded as sub-groups of polychaetes. Annelids are considered members of the Lophotrochozoa, a "super-phylum" of protostomes that also includes molluscs, brachiopods, and nemerteans.

Excerpted from Wikipedia’s “Annelida” article, available under the CC BY-SA 4.0 licence.