Leaf Sheep in Cozumel, Mexico !
Hello! First post here, hopefully the first of many more to come!
I decided to start a blog about my underwater adventures, photography and stories after what I can probably call one of the most exciting moments I've ever had underwater.
And it wasn't a shark, a giant ray or an epic scenery. It was just around 1–2mm, sitting on a velvety piece of Avrainvillea algae.
Before I continue, just to give a little perspective on why I was so excited, I've been going to Cozumel for a few years now and kind of knew what to expect there.
Crystal clear waters, eagle rays, nurse sharks, lots of little blennies and, if lucky, toadfish, seahorses and even frogfish, to name a few.
I had been to Indonesia just a few months before and seen my first ever leaf sheep (Costasiella kuroshimae) there, and was feeling sad that I'd have to wait a while to get the chance to see them again when I went back to the Indo-Pacific region. (I didn't get the best shots! We only saw them once, so they were top of my list of little critters to find again.)
Heading back to Cozumel, we decided to do our regular night dive at Tikila Beach, across the road from our hotel, Casa del Mar. It's one of my favourite dives, as we can just go with our own flow and do a nice long dive taking photos and videos of this shallow nursery full of macro life and other night-dwelling creatures.
It was close to an hour into the dive when I spotted some little spiky-looking things on a piece of algae. They were only about 1–2mm big, so it was impossible to tell what they were. I went closer to take a look through my camera, thinking it must be some sort of water bug. And theeere they were!! Tiny little leaf sheep! I couldn't believe it. They were not supposed to be there?! I took some shots as my heart started to race, and I knew I was blowing through my air fast. Before it was too late, I went to get my dive buddy, who was trying to show me a mantis shrimp (as he knew I loved them), but I was not interested and convinced him to come see what I was seeing. He was also mind-blown. We were putting our hands on our heads and making head-explosion gestures to show our excitement.
These were not the kind we'd seen in Indonesia (Costasiella kuroshimae). These were Eyespot Costasiella (Costasiella ocellifera). But they were still Shaun the Sheep, and that was incredible! My dive buddy had been going there for over 10 years and he'd never encountered them before. The next day, we asked some of the guides at Marine World Cozumel dive centre if they'd ever seen them. Neither had they.
To my surprise, I saw a couple of posts online that people had shared about seeing them there, at the same dive spot. I also saw a post by the Cozumel Coral Reef Restoration Program saying that they had discovered 7 new sea slug species exactly a year before (most of which we saw on that same dive!) So it was pretty new, and not widely known still.
We went back there the next evening. We spotted multiple algae with lots of little sheep grazing around them, pretty easily. To our surprise, when we went back in the early afternoon the next day, they were nowhere to be seen. We only caught a glimpse of a couple hidden inside one piece of algae, but the others had all retreated.
As these are solar-powered slugs, through a process called kleptoplasty, they eat algae and store its chloroplasts in the little spiky structures (cerata) on their backs, allowing them to photosynthesise using sunlight! So, to our surprise, these ones only seemed to be out and about at night during our visits, which left us with another mystery to solve!
Here are some photos of leaf sheep and various other tiny sacoglossans we encountered along the way:
Costasiella ocellifera
Other species we found at Tikila:
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