Errantia

Weigert, Anne & Bleidorn, Christoph, 2016, Current status of annelid phylogeny, Organisms Diversity & Evolution (New York, N. Y.) 16 (2), pp. 345-362 : 354

Errantia

The Errantia are well-represented by a comprehensive amount of studies carried out on the nereidid Platynereis dumerilli , supported by a few studies on the nereidids Nereis (Alitta) virens and Neanthes arenaceodentata and species of the dorvilleid genus Ophryotrocha ( Arendt et al. 2001; Prud'homme et al. 2002; Prud'homme et al. 2003; Tessmar-Raible and Arendt 2003; Arendt et al. 2004; Tessmar-Raible et al. 2005; Kerner et al. 2006; Kulakova et al. 2007; Bergter et al. 2008; Kulakova et al. 2008; Dray et al. 2010; Fischer et al. 2010; Pfeifer et al. 2012; Winchell and Jacobs 2013). Aguado et al. (2015a) propose to study the syllid Typosyllis antoni as a model for this species-rich group, which shows a remarkable variety of reproductive modes. The emergence of P. dumerilii as a thoroughly investigated model species is mainly due to the well-established culture conditions of the life cycle in the laboratory ( Fischer and Dorresteijn 2004). The reproduction cycle of these animals is synchronized with the moon phases, and they display a high ability of regeneration, a hormonal system which is comparatively alike to vertebrates, very simply organized eyes, and a comparatively slow rate of molecular evolution ( Tessmar-Raible and Arendt 2003; Zantke et al. 2014). Genes involved in segment formation and regeneration, nervous system and eye development, photoreception, cleavage patterns, and embryogenesis are studied extensively (see Zantke et al. 2014 for review). Several important techniques for studying the development of these worms have been established, as e.g., in situ hybridization, RNA interference, Morpholino knockdowns, transgenic lineages, or gene modification by transcriptional activatorlike effector nucleases (TALENs) ( Bannister et al. 2014; Zantke et al. 2014; Backfisch et al. 2013; Backfisch et al. 2014). Moreover, it is possible to obtain gene expression data in a cellular resolution for complete individuals ( Achim et al. 2015). Therefore, P. dumerilii is an ideal study object for comparisons of developmental mechanisms with other bilaterian animals. Interestingly, with Platynereis massiliensis , a closely related species is available, which shows pronounced differences in development (direct vs. indirect) and also their reproductive system (hermaphroditism vs. separate sexes). Initial studies regarding their development have been published for this taxon ( Helm et al. 2014).