Nudibranchs, pronounced “new-dih-bronks” are sea slugs, or jelly-like invertebrates that roam shallow ocean floors around the world. There are more than 3,000 known species of nudibranchs and new types are always being discovered. Nudibranchia, their scientific name, means “naked gill”; this refers to the feathery gills and horns that they have on their backs.
All nudibranchs can defend themselves. Some nudibranchs absorb toxins from prey or produce poison from their own bodies. Other nudibranchs store mixtures in their bodies that they let ooze from their skin cells or glands when bothered.
Usually, nudibranchs come in a variety of types; they can be long or short, big or flat, large or small, plain-colored or colorless. They can be as short as a quarter inch or as long as 12 inches. Some types of nudibranchs only live for a month; others live up to a year.
Many slugs are defenseless in the daylight as they swim to feeding spots. However, nudibranchs have a secret weapon—flashy color patterns. Contrasting colors make them noticeable against a reef’s appearance, thus alarming and scaring away predators. Other nudibranchs who don't move as much camouflage themselves with their environment.
Nudibranchs are carnivores who quietly feast on algae, sponges, anemones, corals, barnacles, and even other slugs. They have two highly sensitive tentacles on their heads called rhinophores. These rhinophores help them identify their prey. Nudibranchs often get their coloring from their prey, when they are eaten. Some even retain the poison from their prey and use it as a defense against their own predators.
These sea slugs are well-equipped and powerful creatures!
[Source: National Geographic]