cher chow 周馥溢

Sea Bunnies

March 25, 2019

The diving photographer community has numerous “bucket list” type of organisms. The what is often just as important as how you take the photograph, if not more. Photographs from diving have that added element of shared understanding with the viewer (“It may be a blue blob, but we both know it’s a rare blue blob”). In Hong Kong, we no longer– or probably never– have a lot of those wow factor creatures marine ecosystems. Our bucket list items are probably the most common at dive sites elsewhere.

On top of that, water quality can fluctuate from a milky blue, clear green, muddy olive, to the rare crystal turquoise waters during the winter. But, having been pushed to find subjects during my dives this past year and more, one thing keeps the interest going no matter the conditions– nudibranchs.

Nudibranchs, nudies–or as divers in HK colloquially call them in Chinese– “sea bunnies”, peak during the colder months. They thrive in rocky reef areas, especially at islands with steep granite rock faces underwater, or sometimes in mucky bottoms. I once saw a meme shared by ecologists of a nudibranch and its David Bowie outfit counterpart. For invertebrates that are essentially cannibalistic sea slugs, these sea bunnies come in the most incredible forms and colors.

A fairly common nudibranch, Chromodoris striatella, or as I call it, pajama stripes.

Sometimes nudibranchs are so colorful or opulently decorated that distinguishing their “heads” can be difficult. They generally follow a body shape that’s a little elongated, with a mouth and two “bunny ears” at the anterior and then gills like a sprouted flower on the tail-end of their back. The bunny ears are actually their smell/taste organ and you can tell them apart from the more ridged appearance (usually).

Persian carpet flatworms (Pseudobiceros bedfordi) are technically not nudibranchs although two erected tentacles (at the top of this photo) can sometimes fool you to think it is one.
If you think it’s a nudie and it does this in mid-water, it’s not one! I also love using this photo to show people the sheer tornadoes of shrimp larvae.
This little sea bunny was spotted on some turf algae in Hong Kong’s one and only marine reserve. I have yet to identify them all so this is what I call, “the cool firecracker.”
Two nudibranchs looking like they came from two different planets, but found in the same muck!
This little white nudibranch reminds me a lot of the White Rabbit candies I used to love as a kid. Doesn’t it look like a small mochi blob?

Although I’ve spent nearly a year regularly diving in Hong Kong, I haven’t had the time to read up on nudibranchs. In the quickest Wikipedia research I could do, some nudies like the disco medusa above have tentacle-like protrusions called cerata, which are venomous for defense. I have yet to touch one, thank god, but they add to the flair, don’t they?

Flair indeed.

Some nudibranchs are definitely not as conspicuous. I call this big boy below the mucky cocoa dust. I’ve seen them quite a few times now, and they’ve all been on the large side…

I was actually in the middle of shooting another nudie and almost put my hands on this well camouflaged one. It was more than an inch long!

This species of nudibranchs (“black sesame boy”) are one of my favorites, mostly for their posing. They’ve been popping up everywhere on the encrusting algae and these bubble shaped macroalgae in shallow coral areas. Just last week, I saw some that were around half a millimeter long. Those had me squealing.

I still to this day, do not know what this even is, but my best guess was an eccentric subdued nudibranch.
I think this baby pink marshmallow sea bunny is the closest you’ll get to a real life Pokémon.
The traffic cone: Gymnodoris inornata, one of the most common nudibranchs in Hong Kong.

Some sea bunnies are quite uncommon, but most of them pop-up around the tail end of winter time to get busy. This cerata-covered flamboyant nudie is one of those more uncommon species. I’ve only seen this sea bunny once, and it was at a mucky wreck.

Quite an interesting little one if you look hard enough between the tufts of muck, sea moss/encrusting algae, sponges on large boulders. It’s got an interesting frill going on with its back!
I think this nudie looks like candied ginger.

With most of these nudies, you’ll notice they’ve attracted little dots of muck on them too. The algae they love to hang around on are great at grabbing on to all the particles in the water. Sometimes, I do wish I could clean them up with a cotton bud.

“Lemon Peel”

As cute and incredibly beautiful as they are with their colorations, the general rule in nature is that incredibly bright and colorful patterns serve as a visual warning to potential predators that they are poisonous (or pretending to be).

Most of the ones above are quite small, from millimeters to about 2 cm. However, I’ve just recently learned from a dive at Kung Chau that nudibranchs can grow to huge proportions as well.

This nudibranch covered in rosettes and blue dots (you can see its gills on the left) was probably longer than my thumb!
And this bumpy warty dusty nudie was probably around 3 inches long.

No matter how many times I’ve dove in the same spots, thinking I’ll see the same things, nudies keep on coming up with great surprises. If you’re obsessed (I don’t blame you), these sea bunnies I’ve collected over a year in photographs are nothing compared to some actually Insane ones in Indonesia and Philippines. I hope these blobs of color have sparked some joy! Go Google nudibranchs or scroll through that David Bowie-nudie parallel blog for even more ☺