Pascal Kobeh / Pleurobranch nudibranch (Pleurobranchus forskali) Sulu Sea, Philippines

Linda Pitkin / Side-gilled slug, Pleurobranch (Pleurobranchus grandis), at night Gordon Reef, Straits of Tiran, Egypt, Red Sea

Constantinos Petrinos / Side-gilled slug (Pleurobranchus mammalatus) Lembeh Strait, North Sulawesi, Indonesia.

Sue Daly / Yellow-plumed sea slug (Berthella plumula) Sark, British Channel Islands.

Alex Mustard / Two Moon-faced seaslugs (Euselenops luniceps) emerging from the sandy seabed at night, Bitung, North Sulawesi, Indonesia, Molucca Sea.

Francisco Marquez / Nudibranch(Berthellina ilisima) on white background, Islas Marias Archipelago, Marias Biosphere Reserve, Mexico.