The striking colors that make them attractive to underwater photographers are also what warn predators to back-off. Many of them defend themselves by releasing chemicals that make them toxic.
The more than 300,000 known species of nudibranchs can be thick or flattened, long or short, sumptuously colored or plain looking.
Nudis are blind, so they touch, taste and smell through the two highly sensitive horn-like tentacles, called rhinophores, located on top of their heads.
They live at virtually all depths of salt water from Antarctica to the tropics, but reach their greatest size and variation in warm, shallow waters.
These carnivores prey on stinging creatures such as corals, hydroids and barnacles. Some are even cannibals feasting on sea slugs and even their own species.
Their coloring is obtained from the food they eat.
Aeolid nudibrachs keep their prey’s sting and re-use it by releasing on their feather plumes. The plumes also act as gills.
Being hermaphrodites, they can mate with any other mature member of their species and both can become pregnant and lay eggs.
They lay their eggs in ribbons, coils or tangled clumps, up to two million at a time. Like them, their eggs vary in shapes and hues.
Their lifespan can be as short as 1 week or as long as 1 year.
Nudis cannot be fished out of the sea as they lose their shape and beautiful colors. Thus, they cannot be abused by tourists and collectors alike.
The only way to bring home and show the beauty of these amazingl creatures is by taking photographs.
They cannot be kept in an aquarium due to the diversity of their diet. Even underwater, they are more or less confined within special micro-environments.
Their scientific name, Nudibranchia means “naked gills.”