Janolus by Sergi Garcia

Janolus by Sergi Garcia

Nudibranchs in particular are especially popular with divers and underwater photographers because of their often vibrant and beautiful color patterns. The coloration is useful for more than just a pretty photo, however. Bright colors warn predators that these nudibranchs would make a bad meal because they are armed with toxins and other defenses Smithsonian

edit- had to re-upload the photo