Kahlbrock's Glossodoris

This slug is named after a diver with a camera, and that is more representative of the field than it sounds.

Nudibranch taxonomy runs on photographs to an extent almost no other group does. The animals are small, soft, and lose their color within minutes of preservation, so a museum jar tells you much less than a sharp picture of the living animal in place. Amateur photographers working the same coast for years produce exactly that, in quantity, with dates and depths, and the recent revisions of this group lean on their archives. Several 🌊 Red Sea species described in the last decade carry the names of the people whose pictures made them recognizable.

So: milky white, with a dark blue band right at the mantle edge and a sky blue one just inside it, up to six centimeters. Described in 2018 from 🌊 Red Sea material and known from this sea alone, along the Egyptian and Saudi coasts.

The practical part is the food. It eats a mustard-yellow sponge, and it is generally found on that sponge or within a body length of it, which turns finding one from luck into a search: locate the sponge first and work along it. Chromodorids are tied to particular sponges this way, and the tie is chemical as well as nutritional, because what the slug takes from the sponge is the defense it then carries in its own mantle rim.