Nudibranchs - The prettiest slugs you ever did see...

Nudibranch, the world's prettiest slugs. These strange but beautiful creatures bear some of the most enchanting colours, patterns and shapes of any animal, almost a canvas for Mother nature to express her wild creativity.

Nudibranchs are mollusks, in the Gastropoda class which include slugs, snails, and limpets. At their larval stage they have a shell, but once in adult form it disappears. There are over 2,000 known species, with new ones constantly being discovered. They are found throughout the world's oceans, but are most abundant in tropical, shallow waters. Their scientific name, Nudibranchia, means naked gills, which describes the feathery gills and horns that most of them have on their backs.

These sea slugs are also hermaphrodites. This means that each one is simultaneously a male and a female, possessing reproductive organs of both sexes. While mating they fertilise each other, although a nudibranch cannot fertilise itself. Their lifespan varies quite widely, with some only living less than a month, and others living up to one year.

Nudibranchs lay their eggs in a spiral as shown above. Females lay thousands and thousands of eggs and then arrange them like wavey tortilla bowls that come in all manner of hues. It is the characteristic of egg ribbons that help scuba-diving biologists to track down nudibranchs and to identify the species that laid them.

Nudibranchs are usually oblong in shape, but can be thick or flattened, or long or short. Majority of them are ornately coloured, however, some lack in colour to match their surroundings to camouflage. They can grow as small as 0.25 inches or as large as 12 inches long.

Some are poisonous while others pretend to be poisonous, which is evidently shown by their vibrant colours. For protection they feed on stinging cells of hydroids and then store them in the rear of their bodies for protection. Another method of protection is where nudibranchs ingest the toxins from sponges and become toxic and inedible.

They are carnivores, some species eat other species of nudibranch, where as others even eat their own species. To identify their prey, they have two highly sensitive tentacles on top of their heads, called rhinophores. These creatures acquire their colouring from the food they eat. This usually helps in camouflage, and with some even retain the foul-tasting poisons of their prey, which they can then emit as a defence against predators.

Nudibranchs really are some of the most beautiful predators in the ocean.