Nudibranchs

Picture: Jorunna Funebris

Nudibranchs are marine snails that lack shells and are known as sea slugs. They are found throughout the world’s oceans, but 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. They can be as small as 6 millimeters or grow as large as 35 cms long.

They are carnivorous, 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.

Since there are over 3000 species, they are a divers dream. With such a huge variety of sizes, shapes and colours they are a fantastic subject for photography.

Our artificial dive site “Junkyard” has huge numbers of Sea Hares (Aplysia Korudai) at certain times of the year. This particular species of Nudibranch loves to munch on the Algae that occasionally blooms on the site. They have a great way of travelling longer distances by “flying” with their “wings”

If you want to learn more about Nudibranchs, then check out the Reef Check Eco Diver Course, which covers a range of fish, invertebrates and substrates while adding valuable research data to a global database.