Alex Mustard,Alex Mustard / Nudibranch (Flabellina nobilis) photographed in the field aquarium in Gulen, Norway. North East Atlantic Ocean.

Alex Mustard,Alex Mustard / A nudibranch (Flabellina nobilis) feeding on a solitary hydroid (Tubularia indivisa), note how the hydroid is bent back as it is pulled into the nudibranch's mouth. Gulen, Bergen, Norway. North East A...

Alex Mustard,Alex Mustard / A portrait of a nudibranch ( Limacia clavigera) searching for food on algae. Gulen, Norway. North East Atlantic Ocean.

Alex Mustard / 2020VISION / Nudibranch (Limacia clavigera) feeding on Sea matt bryozoan, growing on kelp frond, Shetland Islands, Scotland, UK, June

Alex Mustard / 2020VISION / Nudibranch eggs (Tritonia hombergi) Loch Carron, Ross and Cromarty, Scotland, UK, April

Alex Mustard / 2020VISION / Nudibranch (Polycera quadrilineata) portrait on a kelp frond, Island of Coll, Inner Hebrides, Scotland, UK, June.

Alex Mustard / 2020VISION / Nudibranch (Polycera quadrilineata) feeding on sea mat (bryozoan) growing on kelp frond. Shetland Islands, Scotland, UK. June.

Alex Mustard / 2020VISION / White nudibranch (Eubranchus farrani) on kelp frond, Lunna Kirk, Shetland Islands, Scotland, UK, June

Juergen Freund / Detail of Nudibranch (Dendrodoris tuberculosa) Batangas, Philippines.

Juergen Freund / Nudibranch (Jorunna funebris) feeding on its preferred sponge, Kimbe Bay, West New Britain, Papua New Guinea

Juergen Freund / Nudibranchs (Chromodoris lochi) crawling on a sea squirt. North Raja Ampat, West Papua, Indonesia.

Juergen Freund / Nudibranchs (Hypselodoris / Chromodoris bullocki) mating and laying eggs, Lembeh Strait, North Sulawesi, Indonesia