The Silt is Alive!

February 9, 2015

Diving in Singapore waters may be daunting for many divers who are accustomed to high visibility waters and at first glance it may seem like there is nothing much to be discovered in the silt ridden reef scape. That’s why the Hantu Blog works hard to train volunteer guides that can help visitors discover and appreciate the hidden wonders of local reefs! Look beyond the silt curtain and take a closer look at beauty often over-looked, like these tentacled autozooids of a toadstool leather coral (Sarcophyton spp.). These are the branched feeding polyps of Alcyoniid soft corals, commonly called leather coals because its tissue is firm and soft, much like the texture of leather. Some sea turtles like to eat leather coral.[1]


Many species of leather coral can be found along the shallow reefs of Pulau Hantu. Most of them occur on the reef flat or reef slope, some even get exposed during the low tide. When they are fully submerged, they stand upright and expose their tentacles like the colony above!

If you are looking for crabs, cowries and tiny brittle stars, a good place to search might be amongst the branches of flowery soft corals like the one above! This particular colony might be a bit too small to find commensals though, but you never know! So it’s always worth taking a peek!

A synaptid sea cucumber works on something tasty along the reef crest.

Feathery tube worms find the reef a perfect place to make a home!

Pen shells (Pinnidae), a type of clam, are nondescript and spend their lives wedged between coral rubble or rocks and stones. They are often harvested for their flesh. During high tide, they open their shells a little, like in the above photo. They then generate a current of water through the shell and sieve out the food particles with enlarged gills. When the tide goes out, they clamp up their shells tightly to prevent water loss.[2]

Zoanthids are commonly found in mats along many of Singapore’s reefs. Pulau Hantu, Labrador Park and Sisters Island, are some of the reefs where we can find this particular type of broad zoanthid that has polyps that resemble tiny anemones and has its oral disc propped up on a stalk.

Fan-bellied filefish blend in perfectly well with Hantu’s reef scape!

Anemonefish make no effort to blend in with their reef. When threatened, they simply dart in amongst the tentacles of their host anemone!

Three types of anemonefish can be encountered at Hantu – False clown anemonefish (previous), Tomato clown anemonefish (above) and Saddleback anemonefish.

Not to be confused for an anemone, these are tentacles of a mushroom coral.

Between the submerged patch reefs of Pulau Hantu are shallow sandflats matted with spoon seagrass (Halophila ovalis). Amongst the seagrass we can sometimes find these Swimming anemones.

The Fringe-eyed flathead (Cymbacephalus nematophthalmus) is really easy to miss!

Clockwise from top: Black phyllid nudibranch, Elysia ornata, Slender Ceratosoma (Ceratosoma gracillimum) and Chromodoris lineolata.

This octopus does an almost perfect job of hiding itself!

If you’ve ever felt nervous about diving in Singapore because of the low visibility conditions, we hope we get inspired to join us and our volunteer crew after checking out just some of the cool things that can be spotted in Singapore’s city reefs!

Our coasts are ceaselessly being developed and transformed. It’s really important that we continue to learn and discover about our reefs, as well as recognise it’s importance to our natural and national heritage! Few urban cities in the world can boast belong located right next to living reefs such as ours where many species can be encountered without much effort!

Remo Orsoni is a visitor from Italy and joined us for his first experience of Pulau Hantu today. After this first dive he shared, “This dive was really good! I’m surprised! There’s so much life. I can only imagine what it might have been like 10 years ago. You have to do all you can to protect it!” Thanks Remo, for discovering Singapore reefs with us! We’ll keep trying!

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