Dive Travel — Cape Town, South Africa
Nudibranchs, or nudies, are captivating creatures. They exist underwater where few people can enjoy their variety, vibrance, and small sizes. But, once discovered, many underwater enthusiasts are captivated.
In my hometown of Gordon’s Bay, False Bay, we are lucky to find around 75 species. When photographing nudibranchs, you’re never disappointed. Spotting new ones is an exciting challenge. My dive buddy and I often see how many species we can find in one dive. Most are endemic, and many have descriptive nicknames like gas flame, candy, or frilled.
What is a nudie?
They are also known as sea slugs but without shells. After their larval phase, they shed their shells. Nudibranch, or “naked gills,” refers to the external gills on their backs. Others have brightly colored protruding organs called cerata on their bodies.
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Left: the naked gills of a Black nudibranch. Right: cerata covering the back of a White-edged nudibranch. |
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They have tentacles on their heads called rhinophores, which are sensitive to touch, taste, and smell.
Many can be poisonous as they are able to steal stinging cells from their prey for defense. Others mimic the texture and color of their surroundings for camouflage. Nudibranchs are carnivorous, eating sponges, hydroids, bryozoans, and some eat other sea slugs or their eggs.
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| A well camouflaged Orange Dorid (Rostanga elandsia) looks like the orange sponge it feeds on. | |
These diverse species are found in oceans worldwide in extraordinary shapes and colors, from cold to warm and shallow to great depths, making them popular and sought after by divers everywhere.
Common species in Gordon’s Bay
Common species found in Gordon’s Bay are:
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Gas flame nudibranch (Bonisa nakaza)
Coral nudibranch (Phyllodesmium horridus)
Red-spotted Dorid (Chromodoris heatherae)
Fiery nudibranchs (Okenia amoenula) with their egg ribbon
Crowned nudibranch (Polycera capensis)
Black nudibranch (Tambja capensis)
Whip-fan nudibranch (Tritonia nilsodhneri)
Two Silvertip nudibranchs (Janolus capensis) with their egg mass
Diving for nudies
Enjoying sea slugs can be a rewarding part of your scuba diving, especially if you’re into macro photography since they’re small subjects varying in size from 4 to 600 mm.
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Purple lady nudibranch (Flabellina funeka) |
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Nudies offer divers interesting, stationary subjects to photograph. They create beautiful, intriguing, and often otherworldly images.
Check my TikTok tips for excelling in underwater photography.
I got into this species because Gordon’s Bay often has low visibility due to the nutrient-rich water. With visibility of only a few meters, you focus on smaller marine animals.
This has been a blessing in disguise. My appreciation for our unique environment is much deeper now. The macro world is its own universe, easily overlooked without paying attention.
Diving for nudies is exhilarating and fun.
Water visibility & biodiversity in Gordon’s Bay
Winds and the earth’s rotation cause deep water upwellings to bring nutrient-rich water to the surface, supporting seaweed and plankton growth. Upwelling generates some of the world’s most fertile ecosystems.
The nutrient-rich water promotes algae blooms, creating the low visibility and green water often seen here.
Luckily, visibility isn’t always low; we can have 5 and 15 meters.
Upwelling usually brings deep cold water to the surface, making it a clear blue and very cold. We eagerly dive our vibrant reefs in 15-meter visibility.
Wandering through the sea-fan forests of Gordon’s Bay and its surrounds is astonishing. This densely populated biodiverse area is supported by the nutrient-rich upwellings and, to a lesser extent, the runoff from the mountains and river inlets.
Seasonally alternating species
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| Cape Dorid (Hypselodoris capensis) left and the Ink-spot nudibranch (Ceratosoma ingozi) right. | |
Local naturalists and nudie fundis documented an alternating presence between the Cape Dorid (Hypselodoris capensis) and the Ink-spot nudibranch (Ceratosoma ingozi). One population increases as the other decreases. One species may be absent for years before reappearing.
Rare nudies to look out for
These elusive species are prized sightings for underwater photographers and marine enthusiasts. While they may be challenging to spot, the thrill of discovering one of these rare nudibranchs makes every dive an adventure.
Here, rarer species found include:
Variable dorid (Aphelodoris brunnea)
Elegant nudibranch (Cratena sp.1)
Orange-lined crowned nudibranch (Polycera sp.2)
Verconia protea dorid
Brush nudibranch (Tritonia sp.2)
Candy nudibranch (Cuthona speciosa)
Olive nudibranch (Facelina olivacea)
Conclusion
Gordon’s Bay offers a unique underwater experience for nudibranch enthusiasts. The diverse ecosystem, influenced by nutrient-rich waters, provides an ideal habitat for these fascinating creatures. Whether you’re a seasoned diver or a curious beginner, exploring the world of nudibranchs in this area can be incredibly rewarding.
By developing your observation skills and learning about various species, you’ll gain a deeper appreciation for the intricate beauty of marine life. Remember to practice responsible diving techniques to help preserve this delicate ecosystem for future generations to enjoy.
Gordon's Bay offers activities for all ocean enthusiasts, from snorkeling, freediving, and shore dives to boat dives. Book your dive holiday today.
We Protect what we Love. Join the movement!
by Madelein Wolfaardt
All images ©️ by @sealife_madeleinwolf
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