The Shaun the Sheep nudibranch, also known as Costasiella kuroshimae, is one of the rarest and most beloved macro species in the diving world. In Maumere Bay, we were lucky enough to find one. Here’s everything you need to know about this tiny green wonder and why spotting it is such a big deal.
A Rare Find in Maumere’s Muck
In our experience, some of the most exciting marine encounters don’t involve size or speed. They happen on the sand, in the quiet corners of a dive site, where something the size of your fingernail can completely steal the show.
That was the case recently when we spotted the Shaun the Sheep nudibranch. A macro enthusiast’s dream, this tiny sea slug is not just rare, it’s also ridiculously cute. And yes, it really does look like the cartoon sheep it’s named after.
What is the Shaun the Sheep Nudibranch?
Scientifically known as Costasiella kuroshimae, this nudibranch was first discovered in 1993 near Kuroshima Island, Japan. It has since been recorded in a few tropical pockets across the Indo-Pacific, including Japan, the Philippines, and parts of Indonesia. That includes us here in Maumere Bay, which makes it extra exciting for our divers.
At full size, it measures only five millimetres long. But what it lacks in size, it makes up for in personality. It has a green body, a white head, and two black eyes that give it the unmistakable appearance of a cartoon sheep. Some individuals have white lines, yellow accents, or purple and green dots. Every one is unique.
Why Is It So Special?
The Shaun the Sheep nudibranch belongs to a group of sea slugs called sacoglossans, but what really sets it apart is a rare ability called kleptoplasty.
In simple terms, this nudibranch steals chloroplasts from the algae it feeds on. Once ingested, the chloroplasts remain active inside the slug’s body, allowing it to photosynthesise like a plant. That means it can literally generate energy from sunlight, a trait shared by almost no other animal on the planet.
The green, leaf-like appendages on its back, called cerata, help it soak up the sun. This is where the nickname leaf sheep comes from.
Where and How to Spot One
You’ll usually find these nudibranchs in shallow waters up to ten metres deep, especially on algae-covered sandy bottoms or muck dive sites. They feed exclusively on green algae, particularly Avrainvillea, which is why muck diving in Maumere offers a chance to find them.
But be warned. They are very rare, and even when present, they are extremely easy to miss. A good guide and a sharp eye are essential. If you enjoy muck diving and macro photography, this is exactly the kind of species you dream of finding.
Why It Matters
We always say that Maumere is full of surprises. You can go looking for big things like reef sharks or manta rays, and still find yourself completely absorbed by a five-millimetre sea slug that steals the spotlight.
For macro lovers, seeing the Shaun the Sheep nudibranch is something to tell your dive buddies about. Its rarity, its science-fiction feeding style, and its cartoonish looks make it one of the most memorable nudibranchs you could ever hope to see.
Come See What’s Hiding in the Sand
At Happy Dive Retreat, we know the reefs and the muck sites of Maumere better than anyone. If spotting rare critters is your thing, we’ll show you where to look and help you photograph the tiniest, weirdest, and most beautiful marine life around.
Book your dive trip with us now and let’s go find your first Shaun the Sheep.
Visit happydiveretreat.com to plan your dive.
