Chaetophteridae

Chaetopteridae
Scientific classification
Kingdom:	Animalia
Phylum:	Annelida
Class:	Polychaeta
Order:	Spionida
Family:	Chaetopteridae

The Chaetopteridae are a family of marine filter feeding polychaete worms that live in vertical or U-shaped tubes in tunnels buried in the sedimentary or hard substrate of marine environments. The worms are highly adapted to the hard tube they secrete. Inside the tube the animal is segmented and regionally specialized, with highly modified appendages on different segments for cutting the tunnel, feeding, or creating suction for the flow of water through the tube home. The modified segments for feeding are on the 12th segment from the head for members of this family.^[1]

Feeding

The Chaetopteridae have several genera with peculiar and well-studied filter feeding mechanisms. The genera Chaetopterus, Mesochaetopterus, and Spiochaetopterus feed using a thin mucus net suspended across the upper portion of their tube. The mucus net is secreted by a hooplike structure called the aliform notopodia arch. The net can grow at a rate as great as one millimeter per second as water currents generated by the notopodial fans pass plankton through the net. When the net grows large enough it contacts the ciliated cup, which rolls up the net. When the roll becomes large the net is disconnected from the aliform notopodia and is rolled into a ball before the ciliated mid-dorsal groove transports it to the mouth ^[1].

Affinity

Molecular analysis suggests that this group is basal within the annelids, below the sipunculid worms.^[2]

References

1. ^ ^{a b} Ruppert, E., Fox, R., & Barnes, R. (2007). Invertebrate Zoology: A functional Evolutionary Approach. 7th Edition. Belmont:Thomson Learning. ISBN 0-03-025982-7
2. ^ Struck, T. H.; Paul, C.; Hill, N.; Hartmann, S.; Hösel, C.; Kube, M.; Lieb, B.; Meyer, A. et al. (2011). "Phylogenomic analyses unravel annelid evolution". Nature 471 (7336): 95–98. doi:10.1038/nature09864. PMID 21368831.  edit

It can also catch food by using its "fins".