Chaetognatha

included taxa and references - Tree of Life

species classification - University of Michigan Museum of Zoology

classification, fossil record, references and list of valid species - Palaeos web site

ITIS - taxonomy and nomenclatural information - Integrated Taxonomic Information System

IRMNG genera list

taxonomic hierarchy - The Taxonomicon

genome size - Animal Genome Size Database

genome size - Animal Genome Size Database

online article - Frontiers in Zoology

NBN Gateway - data sheet (list of synonyms)