Tricia O’Malley

Rare nudibranch discovery highlights diversity of Bonaire’s reefs

In exciting news for the Bonaire National Marine Park (BNMP), a sighting of Aegires sublaevis, a rare nudibranch, was documented at the Cliff dive site in 2021. Incredibly, this nudibranch has not been documented anywhere in the Caribbean, and this extraordinary discovery showcases the diversity – known and unknown – of the reefs protected in the BNMP since 1979. Bonaire continues to win scuba-diving awards worldwide for its beautiful macro-life and this discovery only further highlights why reef conservation is vitally important.  

Nudibranchs, a type of mollusk, fascinate both biologists and scuba-divers world-wide. A diverse group, members are known for their elaborate colors, ability to photosynthesize, and sometimes cannibalistic behaviors, gaining them a passionate following from both underwater photographers and scientists alike. Forums around the world unite researchers, scientists, and photographers in their quest to discover and document these tiny creatures with big personalities. It is through one such forum that researcher Dr. Leslie Wilk, co-author of Reef Creature Identification: Florida Caribbean Bahamas, tracked down author Tricia O’Malley, an amateur underwater photographer, as she had the only known photographs in the Caribbean of the rare nudibranch, Aegires sublaevis.  

Rare nudibranch Aegires sublaevis. Photo source: Tricia O’Malley

“I affectionately referred to the nudibranch as “Glow Cheese,” because I was unable to find the correct identification. Its brilliant yellow color and patchy skin made me think of a block of Swiss Cheese. I was delighted to discover it at the Cliff dive site – one of my favorite locations for macro life and night diving,” O’Malley states.  

Incidentally, through discussion with Dr. Wilk, O’Malley learned that she’d also documented another rare nudibranch at the same site – an undescribed member of the family Dorididae.  

“I take joy in night diving because the reefs truly come alive in the dark. It is astounding to me that after hundreds of dives at Bonaire, I still discover new and exciting finds on each dive. The Cliff dive site is particularly bountiful when it comes to finding nudibranchs, and I can’t tell you how excited I am to have had the opportunity to see such rare and unusual macro-life. I’m truly honored to live somewhere that declares their commitment to protecting the reefs. It just shows that there is so much more to learn about the delicate reef ecosystem and that the Netherlands should consider Bonaire’s reef to be a crown jewel to be preserved at all costs,” O’Malley continues. 


Unidentified Doridae. Photo source: Tricia O’Malley

In his research, Dr. Wilk also discovered other rare nudibranchs found on Bonaire by local naturalist, Ellen Muller. These nudibranchs are Trapania bonellenae, as well as an undescribed species of Cerberilla. These finds only serve to further highlight the extraordinary diversity of Bonaire’s reef.  

“Recent finds show that Bonaire, in particular, has several rare and undescribed species.  The rarest is Trapania bonellenae, an endemic slug named partly after the island and partly after the local resident who discovered it. Aegires sublaevis, a species rarely seen anywhere, was recently photographed at Bonaire. Undescribed species of Spurilla, Cerberilla, and Dorididae have been found in Bonaire’s shallows, but nowhere else. There is also a rare color form of Elysia flava,” Dr. Wilk states.  

Unknown Doridae. Photo source: Tricia O’Malley

“Such extraordinary aspects of Bonaire’s sea slug fauna extend to other marine taxa. For example, the preliminary results of a 2020 survey of Bonaire’s marine biodiversity, funded by Naturalis Biodiversity Center and the ANEMOON Foundation, discovered the existence of at least seven species of invertebrates that are new to science. I mention the above to highlight that on-going research is revealing Bonaire’s marine life to be more diverse and remarkable than ever expected. Accordingly, governmental authorities that create and implement Bonaire’s coastal development policies should place even more emphasis on making decisions that respect, protect, and preserve its marine environment,” Dr. Wilk states. 



These findings provide exciting new insight into Bonaire’s coral reef ecosystems and the opportunity for new marine life discoveries. It is vitally important to protect an environment where new species are still being discovered. As development on Bonaire increases, so does the pressure on the dynamic reef ecosystem, and it will be crucial that conservation lead Bonaire’s future. 

The discovery of the Aegires sublaevis will be published in the upcoming field guide “Tropical West Atlantic Sea Slugs.” 

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These nudibranch sightings have been stored in 

Species reports by local communities and tourists are invaluable for nature conservation efforts to help increase public awareness and overall species protection.  

You can report your nature sightings and photos on the website or download the free apps (iPhone (iObs) & Android (ObsMapp)). You can also send your information to for support with getting your data stored. 


Article published in BioNews 50.

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