Beneath the waves of the Andaman Sea hides a glowing little predator — sleek, neon-lined, and shaped like a miniature hammerhead shark.
Meet Chelidonura varians, a species of sea slug so visually striking that it looks like a creature straight out of a sci-fi film.
Tiny in size but mighty in function, this sea slug is a favorite among macro divers and marine photographers. With its signature headshape, vivid body lines, and fascinating behavior, Chelidonura varians is more than a pretty face — it plays a crucial role in reef ecosystems and serves as an indicator of a healthy marine environment.
Table of Contents
🔬 Scientific Profile: Chelidonura varians
- Common Name: Hammerhead sea slug
- Scientific Name: Chelidonura varians
- Family: Aglajidae
- Size: 2–4 cm
- Distinctive Features: Black glossy body with fluorescent blue or orange edge lines, a wide, flattened head that looks like a hammer or wings
This species belongs to a family of headshield slugs known for their lack of shells, soft bodies, and highly specialized sensory organs that help them track prey along sandy substrates.
🧠 Micro Predator, Macro Importance
Despite its small size, Chelidonura varians is a precision predator. It hunts flatworms, using chemical cues and vibration-sensitive receptors located in its “hammerhead” extensions to locate prey.
Ecological Role:
- Helps control flatworm populations
- Maintains balance in the coral reef food chain
- Its presence is a positive bioindicator of clean, biodiverse waters
🌊 Where to Find Chelidonura varians in Thailand
This sea slug thrives in tropical waters with sandy reef edges and coral rubble zones — exactly what Thailand’s Andaman coastline offers.
Top spots to find it:
- 🐠 Surin Islands: Great for macro diving, also near the Moken Village
- 🐠 Similan Islands: Night dives often reveal this glowing species
- 🐠 Phi Phi + Bamboo Islands: Shallow water sightings possible during snorkeling
They are most often seen gliding along the sand or hiding under rocks in low-light conditions, especially at night or early morning.
📸 Photography Tips for Capturing Chelidonura varians
This sea slug is a macro photographer’s dream — small, unique, and glowing against a dark background.
Pro Tips:
- Use a macro lens or phone lens attachment
- Dive during dusk or night for optimal visibility
- Keep ISO low and use soft diffused light — avoid harsh strobes
- Don’t touch or prod the animal; it’s extremely delicate
- Look near sandy patches with scattered coral rubble
Patience pays off — these slugs move slowly and deliberately, giving you time to compose your shot.
🎮 From Coral Reefs to Pop Culture
The futuristic look of Chelidonura varians has inspired artists, designers, and even game developers. You may have seen similar designs in:
- Games like Subnautica and Spore
- Sci-fi concept art for alien creatures
- Biomimicry-inspired robotics using its body plan
Nature has always been the original designer — and this sea slug proves it.
❓ Is It Dangerous?
Not at all. Chelidonura varians is completely harmless to humans.
It doesn’t sting, bite, or produce toxins. It’s a peaceful species that simply glides along the reef in search of its next flatworm snack.
🧭 Want to See One in the Wild?
If you’re ready to meet this glowing slug in its natural habitat, we’ve got you covered.
At Love Andaman, our expert-led snorkeling and diving trips give you a chance to explore the most biodiverse corners of Thailand’s marine parks — perfect for spotting Chelidonura varians.
📌 Recommended Tours:
🏕️ Looking for a Totally Different Adventure?
If you’re into wildlife and rare ecosystems, you might also enjoy something far from the sea —
👉 Check out this Tanzania Camping Tour