Sea life: Nudibranchs

Gas Flame nudibranch on the SAS Pietermaritzburg
Gas Flame nudibranch on the SAS Pietermaritzburg

Nudibranchs are wildly colourful invertebrates that look like psychedelic underwater slugs. There are countless varieties but it takes a practiced eye to spot them. My excitement when I do find one is totally out of proportion, but I do love these little critters!

Gas Flame nudibranch on the SAS Pietermaritzburg
Gas Flame nudibranch on the SAS Pietermaritzburg

Nudibranch means “exposed (nudi) gills (branch)”, and on almost all varieties you can see little protrusions that are those very gills – looking like fronds. The visual extravagance of these creatures cannot be over-stressed… Their beauty is totally unncessary, and all the more delightful for that.

Gas Flame nudibranch on the SAS Pietermaritzburg
Gas Flame nudibranch on the SAS Pietermaritzburg

Their bright colours tend to warn predators that they aren’t tasty, and nudibranchs have some very ingenious defence mechanisms (thanks to the Two Oceans Aquarium for teaching me this!). They eat things that are unpalatable or indigestible to most other sea creatures, including sponges and hydroids with stinging cells. Some nudibranch species then retain the stinging cells in their bodies, piggybacking off their lunchtime snack’s defence tactics.

Crowned nudibranch
Crowned nudibranch on the wreck near the yellow buoy at Long Beach

We do see nudibranchs at Long Beach – I’ve seen three or four species there, most often the orange-clubbed nudibranch. These tend to be spotted feeding on kelp fronds. Other species can be seen on the rocky reef to the right of the pipeline, and in lesser-dived areas such as the wreck near the yellow buoy. A Frame is another good spot for finding them, particularly in the swim-through. Careful inspection will be rewarded. There are also several varieties unique to the Smitswinkel Bay wrecks – the mechanism of this differentiation astounds and fascinates me – but I haven’t as yet managed to spot any except for a gas flame nudibranch this past weekend on the MV Rockeater.

Gas Flame nudibranch on the SAS Pietermaritzburg
Gas Flame nudibranch on the SAS Pietermaritzburg

Another frequent sighting at Long Beach is the warty pleurobranch, a devastatingly cute and cuddly little slug. They seem to have such personality, with their little eye stalks and bulldozer front ends. They’re not colourful, but lots of fun to watch. We often swim over them in the beds of sea grass, and sometimes on the sand.

Warty pleurobranch
Warty pleurobranch at Long Beach

As a reference for identification you can go to Dennis King’s book – focused on the east and south coasts of Southern Africa, Georgina Jones’s book, or – the mother lode – Guido Zsilavecz’s book. Both of the latter two are concerned with the Cape Peninsula and False Bay. If you’re serious about these gorgeous creatures, I’d go for Guido’s book: Nudibranchs of the Cape Peninsula and False Bay.

Gas Flame nudibranch on the SAS Pietermaritzburg
Gas Flame nudibranch on the SAS Pietermaritzburg


Dive at Long Beach (2010.09.12)

Here’s a rough edit of a lovely dive we did at Long Beach last year (Clare twisted my arm to put this up – I’m not happy with the state of polish of the final version), in 14 degree water with 7 metre visibility. The surface conditions were choppy, as you can see at the end of the video, but under the surface it was lovely.


There’s lots to see. Early on, look out for the common sandprawn (the large, white shrimpy thing). We see lots of their discarded carapaces at Long Beach but this is the only one we’ve seen with a sandprawn inside to date.

There’s also a huge cloud of fry – not sure which fish species, but clearly the imminent onset of spring was encouraging breeding! There’s a very brief shot of a chubby clingfish – the small orange chap clinging onto some sea lettuce, of which there is plenty. Watch out for the Cape topshell on the kelp, and a nudibranch egg ribbon on some green seaweed.

There’s an octopus, a super klipfish, a surprisingly tame puffadder shyshark and his relative the dark shyshark, and a fat longsnout pipefish. We saw a box sea jelly and a night light sea jelly, a peacock fanworm, and my favourite warty pleurobranch. And, of course, there are barehead gobies…

The video concludes with a shot of the inside of the barge wreck at Long Beach.

Dive sites (Sodwana): Caves & Overhangs

We were feeling a little beaten up after our first dive in Sodwana, what with the rough surface conditions that had had more than one of us (no names mentioned) leaning over the side of the boat feeding the fish before AND after the dive! The focus was on getting into the water as soon as possible, because once we were below the surface everything else melted away.

Caves & Overhangs on Two Mile Reef, Sodwana
Caves & Overhangs on Two Mile Reef, Sodwana

The second dive we did was to Caves & Overhangs on Two Mile Reef. The beauty of diving Two Mile Reef is that the longest boat ride you will have to endure is about 10 minutes, and we often spent more time kitting up on the boat than actually locating the dive site!

Justin identifying fish
Justin identifying fish - our underwater naturalist

Justin, Gerard and Tami were doing their Fish Identification dive for their Advanced course, which was a darn good thing because I couldn’t name a single thing I’d seen so far and planned to piggyback off their knowledge! The three of them swanned about with their slates, drawing the things they were seeing. The end results were somewhat hilarious… Compare Justin and Gerard’s slates below (with apologies to both the budding artists for revealing their work in such early stages, and for the water drops – the pictures were taken before I’d removed my camera from its housing):

Justin's fish ID slate
Justin's fish ID slate
Gerard's fish ID slate
Gerard's fish ID slate

I was beside myself with excitement – yelled into my regulator – when I spotted a gorgeous moray eel, with his head sticking out of his cave, opening and closing his mouth to breathe. He was a medium-sized guy, and I tried to stick around for as long as possible watching him, before the surge took me away.

Guinea fowl moray eel on Caves & Overhangs
Guinea fowl moray eel on Caves & Overhangs

My photos from this dive are uniformly terrible – I took several of my eel, and only the one above was vaguely clear. The one shining light however was this picture of what Tony calls the Colgate nudibranch – Chromodoris hamiltoni – who was an obligingly stationary photographic subject. As I recall, I also managed to find something inanimate to hold onto while I took the picture.

Chromodoris hamiltoni
Chromodoris hamiltoni posing on a rock

This dive was far easier and more relaxed for me than the first one. I was wearing a dorky little swimcap (thanks Tami!) which made the rest of the group want to disown me, but which controlled the free flowing hair that had made the first dive tricky, and I was more willing to let the surge move me around.

I hadn’t quite got the knack of pressing the camera shutter button in between surges, but even if I didn’t manage to get pretty pictures of everything, I saw some wonderful parrotfish, unicorn fish, goldies, more than one nudibranch, colourful little wrasses, and an anemone fish rubbing himself all over the largest anemone I have EVER seen. I also saw a host of different kinds of butterflyfish and angelfish, a nice little yellow puffer fish, Moorish idols (wow!), and a tiny little domino who I stalked until he emerged for a photo.

Brain coral
I love love love brain coral!

Dive date: 8 October 2010

Air temperature: 23 degrees

Water temperature: 22 degrees

Maximum depth: 15.3 metres

Visibility: 12 metres

Dive duration: 58 minutes

Bookshelf: More Reef Fishes & Nudibranchs

More Reef Fishes & Nudibranchs – Dennis King & Valda Fraser

This is the sequel to Dennis King’s first book on East and South Coast sea life, Reef Fishes and Corals. It has a similar layout and is of similar length and dimensions. It’s a useful size for travelling around with, like its predecessor.

More Reef Fishes & Nudibranchs
More Reef Fishes & Nudibranchs – Dennis King & Valda Fraser

Several more reef fish are shown and described here, filling in many of the gaps of the previous volume.

This volume doesn’t cover coral at all, but includes a section on nudibranchs. I’m afraid the SURG team have spoiled me for nudibranch identification, and the nudibranch section of this book frustrated me for several reasons.

It doesn’t provide common names for the nudibranchs – so I had to tell people I’d seen a Chromodoris hamiltoni (Tony called it a Colgate nudibranch because it looked like a squeeze of toothpaste). Also, there’s only one picture of each variety, which I suppose is to be expected in a book that attempts to cover a wide variety of fish and other marine species… But given the degree of variation within one type of nudibranch, it can be tricky to make a positive identification with only one photograph to go on.

Buy it here.

Bookshelf: Nudibranchs of the Cape Peninsula and False Bay

Nudibranchs of the Cape Peninsula and False Bay – Guido Zsilavecz

Published by the Southern Underwater Research Group (SURG)

This is the second book by Guido Zsilavecz and the third Southern Underwater Research Group (SURG) publication. It’s all about nudibranchs, the little invertebrates of which we have a huge variety here in the Cape. They’re brilliantly coloured, but can be hard to spot. With practice I am learning where to look for them!

Each type of nudibranch is illustrated with four photographs, which is useful as there is some variation even among multiple nudibranchs of the same type. The photographs are labelled with the name of the dive site at which they were taken, which is very useful as it gives one an idea of where to look for the little critters.

Sometimes they are photographed with their egg ribbons – I often see coils of eggs at Long Beach, but have never been lucky enough to spot the smug nudibranch next to her handiwork.

Tony has an enormous book that covers nudibranchs the world over, but I prefer this volume because it’s focused on the geographical region in which I do most of my diving. It’s also of very manageable dimensions in terms of how many different nudibranchs are covered. New species are being discovered all the time, so if you spot and photograph one that looks unfamiliar, the good folks at SURG will be very happy to examine your photo and try to identify (or, even cooler, name) it for you.

You can purchase this book from SURG – there are order details on their website and they will post it to you directly. Otherwise it’s available in good dive shops in Cape Town.

Exploring: Fisherman’s Beach

We’ve driven past Fisherman’s Beach countless times on our way to stalk the baboons at Miller’s Point, and it’s been on the to do list to dive for a while. We’d heard that it was an easy dive akin to Long Beach, and a good training venue. Also, the little wave breaking on the bright white sand makes it look almost tropical – very inviting.

We ended up diving it the same day as we checked out Sunny Cove. It’s very pretty, with low rocky reefs on either side of the beach, and a wide strip of sand across the middle. There’s lots to explore, and it certainly isn’t as busy as Long Beach. It’s a short hop down the coast to A Frame, and the marine life is thus very similar. There’s a little bit of kelp, but it’s not dense and because of the layout of the site one tends to swim around rather than through it.

Tony’s camera misted up a bit in the warm car between dives, so he didn’t take many photos, but the invertebrate life poses very nicely and there is a lot of colour and light owing to the shallowness of the site.

Fisherman’s Beach is quite exposed, far more so than Long Beach, and we’ve seen that the wave on the beach can get angry in a big swell. Also, there’s a lot of fine sand in between the rocks, and I’d imagine this can get stirred up and decrease visibility quite a lot in inclement conditions. Even some of my careless fin kicks enveloped me in a cloud of particles – so this is perhaps a good place to take more advanced students (for dives three and four of an Open Water Course, for example).

There is parking across the road, and space to kit up on the pavement or on the grass above the beach. There is an easy staircase down to the sand, and although there is more wave activity than Long Beach most of the time, it’s not as intimidating as the Clan Stuart can be.

Fisherman's Beach
Fisherman’s Beach – walk down the beach and into the sea

Verdict: Potentially a good training site, well suited for macro photography, and an easy equipment testing location for when Long Beach is too busy or too familiar.

Dive date: 4 July 2010

Air temperature: 24 degrees

Water temperature: 13 degrees

Maximum depth: 8 metres

Visibility: 12 metres

Dive duration: 37 minutes

Exploring: Sunny Cove

Tony has been wanting to dive Sunny Cove practically since he first set foot in Cape Town, having read in an old book on South African dive spots (The Dive Sites of South Africa – Anton Koornhof) that seahorses had been found there in the sea grass. Tony loves seahorses.

I put my foot down, repeatedly, until it was the dead of winter and the Sharkspotters website told me that not a single great white had been seen patrolling the coast for a couple of months. Sunny Cove is at the end of Jagger Walk, the catwalk that runs along the western edge of Fish Hoek Bay. It’s the site of at least one fatal munching by a great white, and I didn’t want to take any chances.

Sunny Cove railway station
View from the bridge over the railway line towards the dive site

It’s a shore entry, and we parked on the road at the bottom of the steps over the railway line. It’s quite a strenuous walk over the bridge with all your kit on. We spent a while figuring out where to get in – you have to clamber over some rocks, and make your way through dense kelp before getting to a clear spot. Once we decided where to get in, we were glad to be wearing thick wetsuits, otherwise we would have been scraped and scratched quite liberally! There is a huge submerged concrete block just where we got in – at first I tried to swim over it, but realised it was in only a few centimetres of water, and made my way around it. (Fortunately there was no one on the shore with a camera!) Cape Town shore diving is hard on your kit.

Sunny Cove
Our entry point is on the far left, almost out of the photo, where the straight piece of rock sticks out.

The actual dive site is aptly named. The sun streams in through the kelp, and the sea floor looks a lot like Shark Alley near Pyramid Rock – lots and lots of urchins, with pink-encrusted rock formations. We saw a little bit of sea grass, and spent a lot of time examining it for signs of life, but didn’t even find a pipe fish, let alone seahorses! There’s a lot of invertebrate life on the rocks – feather stars, brittle stars, abalone – and we saw quite a few fish.

We did see the deep channel that the sharks probably use to get in and out of Fish Hoek Bay. We were hoping to spot the beacon that records movements by tagged sharks past Sunny Cove, but no luck there. We did not explore much to the south of our entry point – that’s on the to do list (along with more sea horse hunting) for another shark-free day.

Verdict: Shallow, easy dive but a fairly tricky entry and exit. Infrequently dived, so rather more lush and unspoiled than busier sites. Videos of our dive are here and here.


Dive date: 4 July 2010

Air temperature: 21 degrees

Water temperature: 13 degrees

Maximum depth: 10 metres

Visibility: 6 metres

Dive duration: 32 minutes