Underwater Photographer Captures Humble Sea Slugs as They Turn Self-Defense Into Art

highly toxic nudibranch

David Doubilet, who has been photographing the world’s oceans for half a century, and he certainly has an immense portfolio of stunning underwater life and activity. In this featured series he introduces us to some rather delightful and colorful creatures. Called a Nudibranch, these are marine ‘sea slugs.’ Diminutive in size, these ‘sea slugs’ come in a wide variety of colors and are quite visually striking to look at as evidenced by Doubilet’s shots.

poisonous nudibranch

The word nudibranch derives its name from the word nudus meaning naked and brankhia which means gills, in reference to the gill-like appendages that usually stick out their backs. The nudibranch has poor vision and their sense of direction comes from their rhinophores at the top of their head as well as from oral tentacles near their mouths. They also have a single foot that leaves slimy trails behind them.

toxic nudibranch

Over 3,000 species of nudibranchs are known to exist. These colorful creatures range in size from a miniscule few millimeters to as long as 12″.  They can weigh up to just over 3lbs. There are two main types of nudibranchs; the dorid nudibranchs and eolid nudibranchs. All nudibranchs are sea slugs; however, not all sea slugs are nudibranchs. Nudibranchs subsist by eating colorful food, which is what gives them their vibrant colors, as seen here in Doubilet’s delightful pictures.


These colors have several uses such as to camouflage them or to notify potential predators of the poison that lies within them. Dorid nudibranchs create their own poisons or absorb toxins from their food and discharge these into the water when they feel threatened. Despite the noxious taste they can direct to their perceived predators, almost all nudibranch pose no harm to humans.

highly toxic sea slug

David Doubilet has a long and special relationship with the sea. He started snorkeling at the age of 8. By age 12 he was already dabbling in underwater pictures, using a Brownie Hawkeye camera ingeniously stuffed into a rubber anesthesiologist bag. Ever the enthusiast, the bag was filled with air to keep water out, but which also made it difficult to keep submerged.

poisonous sea slug

David has come a long way from those makeshift beginnings, mastering the techniques of shooting with water and light to emerge as one of the worlds’s most celebrated and respected underwater photographers. Doubilet is contributing photographer for National Geographic Magazine. He has published close to 70 stories since his pilot assignment way back in 1971.

toxic sea slug dangerous sea slug

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Patricia Ramos

Patricia Ramos

I am a freelance photographer who is no stranger to smudged lenses, long hours in front of the computer, heavy camera bags (and the back aches that ensued) and missing lens caps. If you know what I'm talking about, you probably have as much love and passion for photography as I do.