Facts about Nudibranchs.
Nudibranchs are soft bodied, marine molluscs that shed their shells after their larval stage. They normally have extraordinary colouration patterns and prominent forms. The word nudibranch comes from the Latin word nudus meaning ‘naked’ and the Greek word brankhia that means ‘gills’. More than 3,000 species of nudibranchs have been described worldwide. Nudibranchs can occur in all oceans, from the tropics to the Antarctic and live from shallow, coastal waters to depths of 700m. Nudibranchs are often referred to as sea slugs, but most sea slugs belong to other taxonomic groups that are not related to nudibranchs.
Nudibranchs are benthic animals (living on the bottom) except the two genera Glaucus and Glaucilla that float upside down just under the ocean surface. Nudibranch species vary in form, but all are bilaterally symmetrical (when dived will have mirror image halves). They have simple eyes set into their body that can only distinguish between light and dark. Their body sizes are from 20mm to 600mm.
Nudibranchs have developed different techniques to protect themselves from predators. Some nudibranchs mimic their surroundings and look like the sponges or soft corals they live on. Other nudibranchs have bright colours and patterns to fool the predators into thinking they are poisonous. Some species do have stinging cells in their bodies after feeding on Hydrozoids, however, these stinging cells do not affect the nudibranchs, but can be irritating for a predator. In a similar way, some species of nudibranch accumulate chloroplasts from the algae they eat, then they use the chloroplasts to photosynthesis themselves for energy.
All nudibranchs are hermaphroditic, meaning to have both male and female reproductive organs. They cannot fertilize themselves and therefore after mating with another individual, both will lay eggs in a gelatinous spiral. All nudibranchs are carnivorous; feeding on sponges, hydroids, bryozoans, sea slugs, barnacles, fish eggs and sea slugs eggs and some species are even cannibals (praying on their own species.)