How I Got the Shot: Shaun the Sheep, Costasiella Kuroshimae – The Leaf Sheep

This characterful critter appeals to viewers as its face resembles the character “Shaun the Sheep”. Often described as a tiny nudibranch, it is actually a sap-sucking sea slug (Sacoglossan) rather than a true nudibranch. They can be found in shallow, warm waters across the Indo-Pacific region, including Japan, the Philippines, and Indonesia. Shaun can even be found in North American locations such as the Blue Heron Bridge in Florida. Found at depths of up to 10m (30 ft), they live directly on Avrainvillea green algae, which is their primary food source. This is a solitary fan algae found on sand or muck and is easy to spot as you swim across the seabed. Individual algae fans will often have whole “herds” of sheep living on them (see images 1 and 2).

They are incredibly tiny critters, ranging from 3–8mm (1/8” to 5/16”) depending on their location; in my experience, examples in Lembeh and Bali tend to be much smaller than those in the Philippines. The first time I was shown a “Shaun,” I did a double-take—what on earth was the guide pointing at? With practice, and by looking through the camera’s viewfinder with an added magnifier, you begin to see them more clearly.

However small the subject may be, our dear “Shaun” is very clever. It practises kleptoplasty, retaining chloroplasts from the algae it consumes. “Shaun” then uses sunlight and photosynthesis to create supplemental energy—hence its preference for shallow habitats. Located on the sand, the algae leaves are not overshadowed by the reef and receive the full benefit of the available sunlight. This ability distinguishes “Shaun” from the more basic nudibranch families.

In my view, it is definitely worth looking for “Shaun” and his mates at the end of a dive when shallowing up over sandy bottoms (see image 3). The black dots between the rhinophores are eyes, but not quite as we know them. They are actually patches of pigment capable of distinguishing between light and shade, helping “Shaun” move into the sun or retreat into the shadows to avoid predators.

I always try to get the “eyes” sharp, just as you would with any portrait, although they can sometimes appear a bit faded. It is the combination of the eyes, rhinophores, and white face that give the creature its sheep-like appearance.

The rhinophores, or "horns," are specialised chemosensory organs used for smelling and tasting. They move up and down, which can be frustrating; when they are lowered, you may need to adjust your angle of view. It is not always possible to get both the eyes and the horns in focus simultaneously, as they often sit in different focal planes—especially given the extremely shallow depth of field required for such tiny subjects. At f/22 or f/29, for example, the depth of field is wafer-thin. In my view, it is best to concentrate on getting the eyes as sharp as possible. Sometimes you get lucky and both the horns and eyes are crisp, but much depends on which way the horns are pointing (see image 4).

The lifespan of these critters ranges anywhere from six months to two years, depending on the habitat and water quality.

“Shaun” can exhibit slightly different colouration depending on where you are diving. This variation is mainly seen in the tips of the horns and the "greenness" of the body, which presumably stems from the specific shade of the host algae. In the Philippines, these slugs tend to have white tips on their horns, rather than the pink or red tips more common in Indonesian examples (see image 5). There is even what I call a “Ukrainian Shaun,” found in Bali and the Philippines, which boasts a striking blue and yellow colouration resembling the Ukrainian flag (see image 6).

How to shoot these tiny critters

Sometimes the stars just don’t align. All the “Shauns” seem to be pointing the wrong way, you can’t get comfortable, your eyes fail you, or the subject simply won't stay still. When I feel like this, I just move on; they can be incredibly taxing, and the whole experience can become very frustrating. However, if you persevere, sooner or later the good images will come. Just remember how tiny these subjects are. It goes without saying that if there is any swell or current, don’t even try!

“Shaun” is relatively easy to find, so it is worth checking every algae leaf as you pass. You do need to look closely, though, as they can look like mere growths or marks on the algae to the naked eye.

Once you have found a subject, make yourself comfortable and ensure your buoyancy is spot on. Observe “Shaun’s” direction of travel and position yourself in front of where he is moving. It is usually easy enough to move around the leaf to get into the optimal position.

I use a long macro lens—a Nikon Z 105mm on my Z8. I occasionally use a teleconverter, though I find that controlling the depth of field becomes even more challenging. My primary tool is a Nauticam SMC-2, which provides 4x magnification with excellent edge-to-edge quality and contrast. I also use a Retra snoot with the smallest insert, along with a separate coloured torch and a spotting light with a homemade snoot attachment for backlighting.

As for settings, I typically shoot at f/29 and vary the shutter speed depending on surge conditions and whether I want to let ambient light into the frame. If you are steady, you can use relatively slow shutter speeds. I tend to use low ISOs for macro shooting, but I will adjust this in combination with shutter speed to achieve the specific effect I am after. I occasionally introduce wider apertures or teleconverters when I want the subject to blur softly into the background (see image 7).

You must bear in mind that with this level of magnification and small apertures like f/29, the depth of field will be tiny and difficult to control. I therefore often use manual focus with focus peaking enabled; the camera display shows exactly what is in focus via coloured lines, allowing me to place the focal plane exactly where I want it.

The angle of view is also critical, particularly if you want to achieve a black or dark background. This can be achieved by using the negative space beyond the algae leaf or simply by using the leaf itself as a backdrop (see image).

Strobe vs. Snoot

You have to choose between lighting the whole frame or concentrating solely on the subject. I use both, but getting strobes in tight enough for such a small subject can be a challenge. Image 9 was taken with strobes, providing a broader light across the frame. In contrast, image 10 was taken with a snoot; this helps the subject stand out and enhances “Shaun’s” texture, as a snoot provides a much harsher, more directional light than a typical strobe.

Image 11 shows another snoot-lit subject positioned on the edge of the algae leaf, which helps create a dark background. To further deepen that black background, image 12 was snoot-lit with the shutter speed set to my camera's maximum sync speed (1/250 sec) and a small aperture of f/29.

In image 13, I have begun experimenting with coloured background lighting—in this case, a blue light to complement the yellow of the “Ukrainian Shaun.” The subject remains snoot-lit, but the shutter speed was slowed to 1/50 sec at ISO 200, while retaining a small aperture for depth of field. I normally ask a buddy or guide to hold the coloured light and wash it over the background. If you try this, experiment with your shutter speed and aperture to achieve your desired effect.

Image 14 takes this coloured background lighting a stage further by introducing backlighting with a small, high-powered torch and a snoot attachment. The settings are similar to the previous shot, but my buddy is also holding a torch at a low angle behind “Shaun.” The snoot orifice is tiny—just a few millimetres across—but it’s enough to rim-light the subject from behind. I had to play with the settings quite a bit to land this shot, eventually settling on f/22, 1/50 sec, and ISO 200.

This approach to lighting and settings can be applied to many tiny subjects, such as hairy shrimp. Good luck shooting your own “Shauns.” They can be among the most frustrating critters to photograph due to their size, but the results are incredibly rewarding once you and your audience appreciate just how minuscule they truly are.

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