Diurodrilus is a genus of tiny marine animals that has traditionally been assigned to the annelid worms, although this affinity is not certain. With a maximum length of 0.45 mm, it has an unusual morphology with many traits not found in other annelids, including a ventral creeping foot.[1][2] Analyses of DNA have both refuted and supported placement within the annelids,[2][3] with the unusual morphology perhaps due to evolutionary progenesis, in which organisms develop sexual maturity while retaining the larval traits of their ancestors.[3]
^Kristensen, R. M.; Niilonen, T. (1982). "Structural Studies on Diurodrilus Remane (Diurodrilidae fam.n.), with Description of Diurodrilus westheidei sp.n. From the Arctic Interstitial Meiobenthos, W. Greenland". Zoologica Scripta. 11: 1–12. doi:10.1111/j.1463-6409.1982.tb00514.x. S2CID84404993.
^ abGolombek, Anja; Tobergte, Sarah; Nesnidal, Maximilian P.; Purschke, Günter; Struck, Torsten H. (2013). "Mitochondrial genomes to the rescue – Diurodrilidae in the myzostomid trap". Molecular Phylogenetics and Evolution. 68 (2): 312–326. doi:10.1016/j.ympev.2013.03.026. PMID23563272.