Twinkle, Twinkle Little Ostracod
Caribbean ostracods are just like lightning bugs ... if instead of having light-up butts, they had light-squirting faces.
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On moonless nights in the Caribbean Sea, the love child of the firefly and the squirt gun—the ostracod—magically appears.
Rising from their usual homes in coral and sand, such ostracods are little arthropods that look more or less like fleas (or perhaps shrimp trapped inside a clams), and are sometimes sweetly called “seed shrimp”. Typically measured in millimeters, ostracods live inside a hinged, transparent shell, legs and all. Don’t let their size and diminutive appearance fool you, though. Their reach far exceeds their tiny appendages’ grasp. Ostracods are found throughout the world’s waters and have even invaded land in places like South Africa and New Zealand, where they live in damp soil.
Although their appearance is nothing to write home about (unorthodox shell notwithstanding), the marine versions may have a special trick up their valves: they can squirt bioluminescent goo from their faces. In most of the world’s waters, this is a simple burst. It’s calculated to startle a predator. But in the waters of the Caribbean, that flak-like function has evolved into a sexy symphony of ephemeral light. Unlike a firefly’s anatomically-fixed light display, an ostracod’s is a temporary art installation housed in a liquid medium. If you were hovering next to one and waved your hand through it, the glow would blow away like smoke.
Science published a lovely video about these ostracods this past week, that highlights the advances in camera technology that have made studying them so much easier over the last decade. But the new footage taken by those cameras is itself spectacular, so please enjoy this holiday light display courtesy the crustaceans of the Caribbean:
That bit about the non-signalling sneaker males (did you see them flit by at 3:26?) is pretty interesting. From reading Marah J. Hardt’s Sex in the Sea, I know that this “sneaking” (females would probably have a different name for it) is a not-uncommon strategy among marine life. But it’s one thing to read about it, and it’s another thing to see the enormous swarm of opportunist sex-seekers tripping over each other trying to get in on the action. You can see how stoked the scientists were about seeing it, too. Better living through technology, friends!
I actually traveled to see these beauties in person and wrote about them for The Artful Amoeba way back in 2014. Some of the folks from the video appear in the text. Sadly, the images are broken now, but it may still be a worthwhile read for those of you interested in a firsthand account of the show. If you’ve ever thought about getting dive certified, I can recommend it for this experience alone.
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Lovely