Diving In Singapore: 🌊 Meet Dardanus megistos — the “Giant with Polka Dots”

Meet the mega son of Zeus and Electra @ Pulau Hantu

Found while diving in Singapore's Pulau Hantu. Photo Credits: J.Bourgeon

Dardanus refers to the son of Zeus and Electra in Greek mythology, while megistos is the superlative of the Greek word mega,

means the largest.

🐚 The White-Spotted Hermit Crab: Singapore’s Bold, Spotted Reef Wanderer

Big claws, bright spots, and a personality that’s larger than its shell.

If you’ve ever done a night dive around Pulau Hantu or St John’s Island, you’ve probably seen it — a large, shaggy hermit crab trundling across the reef floor with a house it clearly didn’t buy. Meet Singapore’s White-spotted Hermit Crab (Dardanus megistos), the island’s most flamboyant crustacean and an unsung hero of our reefs.

This species looks like it walked out of a Pixar movie. With bright red-orange legs covered in neat white polka dots, the Dardanus megistos is easily one of the most photogenic creatures you’ll encounter while diving in Singapore.

Their long, hairy legs peek out from under their adopted shell, making them look equal parts adorable and intimidating. The left claw is massive — a built-in door they use to seal themselves inside their home when threatened.

🎨 Fun Fact: Those bright spots aren’t just fashion — they help break up the crab’s outline in dappled light, acting as camouflage against predators.

🏠 Home Sweet Shell

Like all hermit crabs, the White-spotted Hermit doesn’t grow its own shell. Instead, it “rents” an empty gastropod shell — often from turban snails, conches, or moon snails. As it grows, it has to find bigger real estate.

Underwater, you can sometimes watch one switching homes — inspecting a new shell, testing it for comfort, then quickly transferring its vulnerable soft abdomen inside. It’s nature’s version of a house-hunting show.

🐚 Dive Tip: Always leave empty shells on the reef — they’re not “souvenirs,” they’re future homes for crabs like these!

🌍 Diving In Singapore: Habitat and Where to Find It

The White-spotted Hermit Crab is widespread across the Indo-Pacific, from the Red Sea and East Africa all the way to the Pacific Islands. In Singapore, they’re found in:

• Pulau Hantu (especially at night)

• Kusu Island

• St. John’s Island

• Sisters’ Islands Marine Park

• Occasionally in shallow intertidal zones on rocky shores during low tide

They prefer sandy or rubble seabeds near coral reefs, where there’s plenty of food and abandoned shells to choose from.

🌙 You’re most likely to spot them during night dives, when they emerge from hiding to scavenge.

🍽️ What’s on the Menu?

The Dardanus megistos is the ultimate opportunist. It’s an omnivore and scavenger, feeding on whatever it finds on the seabed — from algae and detritus to small invertebrates and bits of dead fish.

Think of it as the clean-up crew of the reef — always tidying up leftovers, keeping the ecosystem balanced.

⚡ A Shocking Friendship: The Sea Anemone Connection

Some individuals have an interesting roommate — sea anemones like Calliactis that attach to their shell. It’s a mutualistic relationship:

• The crab gets protection from predators thanks to the anemone’s stinging tentacles.

• The anemone gets free transportation and scraps of food from the crab’s meals.

This partnership is so tight that when the hermit crab changes shells, it carefully picks up its anemone and transfers it to the new one!

❤️ Reef Relationships 101: Teamwork makes the tide work.

🦞 Behavior: Bold but Lovable

White-spotted Hermit Crabs are nocturnal and surprisingly curious. Shine your dive light on one, and it might freeze for a second — then wave its claws like it’s sizing you up. If you come too close, it’ll retreat into its shell, using that oversized left claw like a drawbridge.

They’re also known to squabble over the best shells — a comical sight that sometimes ends with one crab walking off with the other’s house!

🤿 Cuddlefish Divers Tip: Observe patiently. Watching their antics is one of the best parts of diving in Singapore.

📸 How to Spot (and Photograph) Them While Diving In Singapore

• Time your dive: Night or early morning dives at Pulau Hantu give the best odds.

• Look low: Scan sandy patches near coral rubble.

• Lighting: Use a soft, diffused torch or strobe to avoid startling them.

• Composition: Get eye-level. Their spotted legs and alert eyes make for perfect macro portraits.

🌱 Role in the Ecosystem

Hermit crabs like Dardanus megistos are unsung heroes. By scavenging dead matter, they help recycle nutrients and keep the reef clean. Their constant shell-swapping also encourages other reef species (like sponges and barnacles) to colonize their discarded homes — turning every shell into a miniature mobile reef.

They might be small players, but together, they’re a vital part of Singapore’s marine biodiversity.

🦀 Singapore’s Hermit Crab Biodiversity

A study by the Lee Kong Chian Natural History Museum (NUS) recorded over 40 species of hermit crabs in Singapore’s waters. The White-spotted Hermit is one of the largest and most easily recognized — and a favorite among divers and photographers.

⚖️ Conservation Status

The species is not currently endangered. However, like much of Singapore’s marine life, it depends on healthy reefs and clean waters. Coastal development, pollution, and shell collection all affect hermit crab populations.

🌊 Every dive you take with respect — neutral buoyancy, no touching, no collecting — helps protect creatures like the White-spotted Hermit Crab.

❤️ Why We Love the White-Spotted Hermit Crab

Because it’s tough, colorful, quirky, and totally unbothered. It’s a survivor thriving in the same waters where cargo ships pass and city lights shine.

For divers, spotting one is always a joy — a reminder that Singapore’s seas are very much alive, full of stories unfolding just beneath the waves.

🐠 Dive with Us to Meet Them!

At Cuddlefish Divers, we love introducing new divers to Singapore’s underwater residents. The next time you join us for a local dive, keep an eye out for these white-spotted charmers — they might just steal the show.https://www.cuddlefishdivers.com/singaporedive