• Daryll Rivett

Naked Gastropods 'Nudibranch' weird and wonderful obsession.

Updated: Aug 30

From the inception of my diving career in 2012 I knew that the underwater world was going to change my life as the feeling of weightlessness, freedom, serenity and interaction with marine life was surreal (like a drug), SCUBA became my addiction. Soon to follow was another new obsession and previously unexplored skillset, Underwater Photography.

To further add to this fascination, I saw my first Nudibranch (Ceratosoma brevicaudatum) in Adelaide, Sth Australia and became intrigued and fixated on the species. I did some further research and stumbled into more than I bargained for, and found there were over 3,000+ different species Worldwide with the most colourful and beautiful variations out there for me to discover.

This was the start of something I was not prepared for, and to this day still keeps me searching and exploring the Oceans for sightings of Nudibranchs I have not yet encountered.


This obsession has led me to travel to some remote, tropical and amazing places that the 'Normal' tourist would not normally travel to, plus different 'Regions' of the world are home to a many and varied species not indigenous to other regions of the world;

  • Indo-Pacific

  • Eastern Pacific

  • Australia/New Zealand

  • Eastern Atlantic/Mediterranean

  • Western Atlantic

  • Indian Ocean/Red Sea

  • Western Pacific

There are already many experts in this field along with many books devoted to identifying, collating data along with recording new species. I am by no means here to re-invent the wheel, just want to share with you my experiences, photo's and collection.

From it's inception (Nudi Obsession) I have utilised the support and expertise of others to accurately identify my sightings. I then manually record (card-file), catalogue and cross reference from Resource Books the Nudibranch's I've seen during my diving career, and will continue to do so until I can dive no-more.


Like any naturalist, hobbyist and collector alike there will always be the desire to chase the unattainable and to fulfil the collection etc etc. My Phoenix is to find the elusive 'Holy Grail' of Nudibranch, the infamous Melibe colemani (Ghost Nudibranch).

So this brings me to July 2019 when I had an opportunity to visit Batangas (Anilao) in the Philippines for a Photography Masterclass dive trip, and I just couldn't let the chance of including an additional week to visit Romblon pass me by. Romblon is known world-wide to be the home of the Melibe species with sightings occurring on a very 100% guarantee on every dive at particular dive sites.


Chasing 'My Phoenix' the Holy Grail of nudibranch's was euphoric with the sighting and witnessing both species of the Melibe (Ghost Nudi). I was blessed and fortunate enough to see and photograph both species, the Melibe colemani and the Melibe engeli, but it got even better - I got to see the Melibe colemani in mating season, witnessing them with their ribbon of eggs, WOW, just WOW.


Pictured below in order is Melibe engeli, Melibe colemani with eggs and both species in the one photo.


I have collected & catalogued 100's of photo's over the years from dive trips, locally in Australia and Oversea's and want to share with you a snapshot of some of the best Photo's & Subjects of this species you may never get to experience.

To date I have personally seen, photographed and catalogued in the vicinity of around 120+ Nudibranch......

Tulamben - Indonesia

Nudibranch are carnivores that slowly ply their range 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 colouring 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 defence against predators.

Komodo - Indonesia

Generally oblong in shape, nudibranchs can be thick or flattened, long or short, ornately coloured or drab to match their surroundings. They can grow as small as 0.25 inches or as large as 12 inches long.

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.

Padang Bai - Indonesia

Both sexes are present in a single nudibranch, but self fertilisation does not occur. Special sperm sacs are exchanged during copulation. However, it may take several days, or even weeks before the eggs become fully developed and are actually fertilised. They are deposited in colourful, ribbon-like strands, often on their favoured food.

So the next time you are out snorkeling or diving keep an eye out for the beautiful Jewels of the Sea!

Reference and thanks to the Indo-pacific Coral Reef Field Guide. Dr. Gerald R. Allen and Roger Steene. ISBN:981-00-5687-7

I hope this Blog has enlightened, educated and expanded your knowledge of the Underwater World and the fascination it brings to thousands of people who dare take the plunge and include Scuba Diving into their world.

Image Copyright of Padi


In closing, 'Take Every Chance You Get In Life, Because Some Things Only Happen ONCE', & let my stories and experience give you inspiration to create your own Moments.


Another 'Rivetting Moment', to inspire & ignite the traveller in you, to broaden life challenges & experiences!!!


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