Though small in size, the nudibranch has made a pretty big name for itself. Nothing but a mere sea slug, this little creature has captured the hearts and cameras of divers around the world with its incredible diversity. To date, there are more than 3,000 known species of nudibranch, each with a unique pattern, colouration, and shape, attracting the interests of expert underwater photographers worldwide.
You may think that the nudibranch would make an easy photographic subject, given its slow nature and vibrant colours, but this little slug has been a challenge to capture for even the best underwater photographers. It’s tiny size and habitat choice of sand and muck pose a challenge for photographers who wish to capture their striking features.
Apart from their show-stopping appearance, nudibranchs also have some interesting traits.
Some are solar-powered, living off the sugars produced by the photosynthesising algae stored in their outer tissues. Others can emit chemical odours to deter predators, with the aeolid nudibranchs even possessing the ability to sting predators with the stored nematocysts of previously-encountered predators.
While it may be tempting to keep these beauties in an aquarium, this is strongly advised against – nudibranchs are extremely sensitive creatures that live in specialised environments in the sea. As carnivores, they have specific diets and require micro-conditions that an aquarium cannot replicate. Confined nudibranchs often lose their form and colour, and the toxins released after death would harm the other aquarium residents.
Unfortunately, nudibranchs don’t live for very long, with most surviving no longer than a couple of months. To ensure the proliferation of their kind, nudibranchs are simultaneously hermaphrodite and can mate with any other nudibranch of the same species. During mating, both individuals function as male and female, simultaneously giving and receiving sperm and eggs.
You can find nudibranchs almost anywhere in the world – one species was even spotted at the North Pole – though they are most common in warm, tropical waters. Given the extraordinary forms and features of nudibranchs, it is no wonder these tiny jewels have become iconic critters of the ocean.
ABOVE A semi-translucent, yet very colourful, gold lace nudibranch atop a coral head on a reef off the west coast of Guam