We thank Wim Wyverman, University of Ghent for useful comments on the manuscript, Mari-Ann Østensen for assisting with cultivation and Torfinn Sparstad for DNA isolation and qPCR analysis. The sequencing service was provided by the Norwegian Sequencing

Centre (www.sequencing.uio.no), a national technology ABT 263 platform hosted by the University of Oslo and supported by the “Functional Genomics” (FUGE) and “INFRAstructure” programs of the Research Council of Norway. “
“Ophiuroids (brittle stars) display extensive regenerative capabilities in both the main disc and arms (Lawrence, 1990). However, it is the latter, which is most commonly studied, across a range of disciplines from ecology (Dahm, 1993, find more Skold and Rosenberg, 1996 and Allen Brooks et al., 2007), through histological characterisation of cellular differentiation (Candia-Carnevali, 2006 and Biressi et al., 2010) through to gene expression analyses (Bannister et al., 2005, Bannister et al., 2008, Burns et al., 2011 and Burns et al., 2012). This regenerative capability is essential to survival, as many populations suffer high levels of sub-lethal arm damage, mainly through predation, but also from abiotic challenges such as wave action, water chemistry and icebergs (Skold and Rosenberg, 1996, Fujita, 2001, Dupont, 2002 and Clark et al., 2007). The rate of arm regeneration can vary dramatically between species, from 0.04 mm day− 1 up to 1 mm day− 1 (D’Andrea et

al., 1996, Dupont et al., 2001 and Clark et al., 2007). The mode of regeneration is also variable. In some brittle stars regenerating arms are highly differentiated from the outset (Clark et al., 2007) whereas others are more flexible and can have rapid growth followed by differentiation (Dupont and Thorndyke, 2006 and Biressi et al., 2010). The genetic control of arm regeneration in ophiuroids is largely unknown, with only the most recent advancements moving the field from single gene studies to transcriptome level investigations PRKACG (Burns et al.,

2011 and Burns et al., 2012). The brittle star used in this study, Ophionotus victoriae, is the dominant ophiuroid in Antarctic Peninsula coastal waters ( Arnaud et al., 1998) and was previously identified as having a very high level of arm damage in natural populations, with up to 97% of individuals displaying signs of previous or current arm injury ( Clark et al., 2007). Combining this with a high incidence of all five arms showing damage (~ 60%) indicates that regeneration plays an almost constant part in the 22 year maximum life of this brittle star ( Dahm and Brey, 1998 and Clark et al., 2007). This high level of damage was suggested to be due to iceberg scouring ( Clark et al., 2007). Experimental manipulation demonstrated that regeneration rate in this species is slow (0.22–0.68 mm week− 1). However, calculation of the Q10 coefficient for this process compared to temperate species (at 2.