Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Spiralia
Cladus: Lophotrochozoa
Phylum: Annelida
Classis: Polychaeta
Subclassis: Palpata
Ordo: Canalipalpata
Subordo: Spionida
Familiae: Apistobranchidae - Chaetopteridae - Longosomatidae - Magelonidae - Poecilochaetidae - Spionidae - Trochochaetidae - Uncispionidae
Spionida is an order of marine polychaete worms in the infraclass Canalipalpata. Spionids are cosmopolitan and live in soft substrates in the littoral or neritic zones.[1]
Characteristics
Spionids have a single pair of flexible feeding tentacles with grooves, arising directly from the prostomium. The mouth has no jaws and the pharynx is partly eversible. Some species have small eye spots and some a central sensory lobe. Some of the anterior segments paired gills. The parapodia or lateral lobes have large lamellae. The chaetae are unbranched capillaries, spines and hooks.[1][2]
Families
According to the World Register of Marine Species (WoRMS), the Spionida comprises six families in a single suborder:[3]
Order Spionida
Suborder Spioniformia
Apistobranchidae Mesnil and Caullery, 1898
Longosomatidae Hartman, 1944
Magelonidae Cunningham and Ramage 1888[4]
Poecilochaetidae Hannerz, 1956
Spionidae Grube, 1850
Trochochaetidae Pettibone, 1963
Uncispionidae Green, 1982
Other families such as Aberrantidae and Magelonidae are sometimes included in Spionida.[5]
References
Annelid Resources
Marine Species Identification Portal
Read, G.; Fauchald, K. (Ed.) (2021). "Spionida". WoRMS. World Register of Marine Species. Retrieved 11 April 2021.
"Magelonidae". Fossilworks. Retrieved 11 April 2021 from the Paleobiology Database.
"Spionida". Integrated Taxonomic Information System. Retrieved 10 April 2021.
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