This one is all about the pictures, because the accompanying text is minimal. Still, fair enough, how far can you get into describing individual sea-slug species?
You get the common and Latin names, family, geographical distribution, size and distinctive features. Typically this boils down to “Yellow-Face, Trinchesia Trinchesia sp. Indonesia, 9mm. ID: red cerata, white apex with tubercles.”
Particularly helpful, however, is the photo index at the beginning of the book that guides you to the right group of nudibranchs. It does make a difference, and the less unproductive leafing around I have to do the better.
Underwater photographers Andrey Ryanskiy and Yury Ivanov say they evolved from being holiday-divers into professionals who carry out hundreds of dives every year in the Coral Triangle countries. Lucky them.
This seems to be naturalist Ryanskiy’s first book with Ivanov, but solo he has previously come up with five other “Reef ID” books, covering Coral Triangle fish, Indo-Pacific crustaceans, the Maldives, Indonesia and the Philippines. They’re doing a useful job.