Nudibranchs, Living Color

ORIGINAL: NatGeo

Toxic nudibranchs—soft, seagoing slugs—produce a brilliant defense.

Photography by David Doubilet. Nembrotha kubaryana

Size: 2.4 inches (6 centimeters)

Photography by David Doubilet. A hard body and thick skin help armor Halgerda batangas against predators. Any that persist learn that the sponge-eater also exudes a toxin.

Size: 1.6 in (4 cm)

Photography by David Doubilet. Asteronotus cespitosus

Size: 8.7 in (22 cm)

Photography by David Doubilet. Chromodoris sp.

Size: 2.4 in (6 cm)

Photography by David Doubilet. Chromodoris annae compensate for their tiny size with loud, contrasting hues—warning predators of a toxic snack.

Size: 0.8 in (2 cm)

Photography by David Doubilet. Bornella anguilla flees danger by folding in its appendages and swimming like an eel.

Size: 2.8 in (7 cm)

Photography by David Doubilet. Cuthona sp. 

Size: 0.7 in (1.8 cm)

Photography by David Doubilet. Flabellina exoptata

Size: 1.2 in (3 cm)