I have the 6th edition of the textbook "Invertebrate Zoology" by Ruppert and Barnes from 1993. I know there is a 7th edition from 2003, but is there and will there ever be a 8th edition? Assuming they should come every 10 years, shouldn't there have been one in 2013? So if Ruppert & Barnes retired, is there any more recent successor or alternative?
A worthy successor to this book series is "Invertebrates" by Richard C. Brusca et al. The latest edition being from 2016, so exactly what I was looking for.