Photo: Florida regal goddess nudibranch

The Florida regal goddess is only one of 3,000 known species of nudibranch—and new ones are being identified almost daily.

Photograph courtesy Gary's Reef Marine Sanctuary/NOAA

Map

Map: Nudibranch range

Nudibranch Range

Fast Facts

Type:
Invertebrate
Diet:
Carnivore
Average life span in the wild:
Up to 1 year
Size:
0.25 to 12 in (6 mm to 31 cm)
Weight:
Up to 3.3 lbs (1.5 kg)
Did you know?
Some nudibranchs are solar-powered, storing algae in their outer tissues and living off the sugars produced by the algae’s photosynthesis.
Size relative to a tea cup:
Illustration: Nudibranch compared with tea cup

The bottom-dwelling, jelly-bodied nudibranch (NEW-dih-bronk) might seem an unlikely canvas for Mother Nature to express her wildest indulgences of color and form. But these shell-less mollusks, part of the sea slug family, bear some of the most fascinating shapes, sumptuous hues, and intricate patterns of any animal on Earth.

There are more than 3,000 known species of nudibranch, and new ones are being identified almost daily. They are found throughout the world's oceans, but are most abundant in shallow, tropical waters. Their scientific name, Nudibranchia, means naked gills, and describes the feathery gills and horns that most wear on their backs.

Generally oblong in shape, nudibranchs can be thick or flattened, long or short, ornately colored or drab to match their surroundings. They can grow as small as 0.25 inches (6 millimeters) or as large as 12 inches (31 centimeters) long.

They are carnivores that slowly ply their range grazing on algae, sponges, anemones, corals, barnacles, and even other nudibranchs. To identify prey, they have two highly sensitive tentacles, called rhinophores, located on top of their heads. Nudibranchs derive their coloring from the food they eat, which helps in camouflage, and some even retain the foul-tasting poisons of their prey and secrete them as a defense against predators.

Nudibranchs are simultaneous hermaphrodites, and can mate with any other mature member of their species. Their lifespan varies widely, with some living less than a month, and others living up to one year.

Invertebrate Features

  • portuguese-man-of-war-06.jpg

    Pictures of a Lethal, Gelatinous Beauty

    The Portuguese man-of-war is infamous for its painful sting, but one photographer finds the beauty inside this animal's dangerous embrace.

  • Photo: Organ pipe coral

    Coral

    It's reef madness in this colorful gallery of coral formations.

  • Photo: Cluster of orange cup coral

    Photo Gallery: Coral Reefs

    About 80 percent of all life on Earth is found in the oceans, which cover 71 percent of the planet's surface. Take a look at how colorful life under the sea can be.

  • Photo: A lobster and crab on the seafloor

    Lobster

    Learn more about these popular crustaceans that some think of only as a meal. Find out the sizes that these sea creatures are capable of attaining.

Photos

  •  Picture of a Malayan tiger

    Pictures: Tiger Subspecies

    Scientists estimate only about 3,000 wild tigers are left in the entire world. Meet the subspecies and see what threats each is facing.

See more animal photos »

From the Magazine

  1. Photo of the lions of the Vumbi pride.

    The Surprising Lives of Lions

    In case you missed it: See these breathtaking videos and photos from inside a wild Serengeti pride.

  2. Photo: Two adult preen, Ireland

    Gannets Pictures

    Champion divers but clumsy landers, doting parents but hostile neighbors—northern gannets abound in contradictions.