Taxonomy

Taxonomy databases

For fish the Fishbase
for Algae the Algaebase
for sponges the World Porifera Database
for hexacorals the Hexacorallians of the world, etc.

For general checking, WORMS (World  Register of Marine Species) where you can validate the species name and be able to identify synonyms.

Each taxa as an expert associated to it and you can also know or contact them.

Regarding sequences I would recommend you BOLD Systems (

http://www.barcodinglife.com/) that associates the morphological characters of specimens and photos with the genetic data. It also imports from and exports data to Genbank.

However you should have into account that the original description of each species should be checked. The Biodiversity Library has a lot of ancient literature.