The most wide scope identifications books for the entire norwegian coast is:
Marine fish & invertebrates of Northern Europe Moen and Sveinsen http://www.komforlag.no/produkt/marine-fish-and-invertebrates-of-northern-europe This is a general handbook mostly based on underwater photos
Other than that the Handbook of Marine Fauna of North west Europe Hayward and Ryland is usually quite good.
Artsdatabanken.no will also be a nice source for this in time, but the new pages are currently under construction
Yes, Hayward and Ryland seems to be nice identification guide for many groups of marine invertebrates, but it will be more useful to use a special literature for each taxon.
If you will need any help with some gastropod groups (excluding Neogastropoda and Nudibranchia) please do not hesitate to ask me.
concerning the marine invertebrate fauna of Norway the series “Marine Invertebrates of Scandinavia” published by Scandinavian University Press is also very helpful ... unfortunately only 10 volumes so far were published ... in detail:
Patrick Louisy's text is a good fish identification manual: A Guide to Marine Fish of Europe and the Mediterranean. I do not know if the ichthyofauna of northern Norway disputes a lot from the Atlantic species reported in the book.
Zooplankton and Micronekton of the North Sea - Marine ...
http://species-identification.org › species › record=The ...
Descriptions, images and identification tools for marine species.
Identification keys http://species-identification.org › identify_speciesThe Marine Species Identification Portal accomodates many keys, either in the form of dichotomous or multiple-entry 'matrix' keys. All keys are listed below ...
Acoustic identification of marine species using a feature library