Dirty Demons and Delicate Crabs

Date December 18, 2014

Over the weekend, there was as big a show of macro wildlife as there was a show of divers! As many as 70 divers from several boats pulled into Pulau Hantu’s reefs for a dive and saw critters like batfish, pipefish, and demon stingerfish. It’s wonderful to have people going out and discovering Singapore reefs, but it also means that we have to take care while diving on the reef and ensure that we are not trampling on or damaging the fragile habitat as we are finning about taking our photographs. 70 people on the reef in a single morning could have a huge impact on the reef habitat if we are not careful. It may sometimes appear that there is nothing on the reef, but many of Pulau Hantu’s wildlife is cryptic and hard to see, like this gorgonian shrimp! (PHOTOS: Ng Boon Leong & Toh Chay Hoon)

It was a shrimp fest on Sunday! Not the barbecue kind, but the transparent kind! Here are two perched on a hydroid!

Another transparent shrimp crawling about on the sediment. See what I mean by well-hidden!

Sea pens may not look like it but they are animals that are related to corals. They poke into the sand and grab food out of the water that’s blowing through in the current. Taking advantage of a good situation is this tiny and delicate crab that’s putting in a good effort to remain hidden. While a sea pen may be a good place for a crab to be based to pick off food bits, it is as good a place for a larger predator to forage for tasty crab morsels.

For a long time, I overlooked the Ceratosoma nudibranch because it looks like a piece of encrusting sponge. When I finally had it pointed out to me by Chay Hoon, I wondered how I could have missed it because many of those around Pulau Hantu are HUGE! Perhaps too huge. They don’t bother with hiding because apart from looking like a sponge, they aren’t very tasty. I’ve seen fish suck a small one in and spit it right out straightaway. They must taste yucky. But they are pretty! Look at those gills!

Gymnodoris rubropapulosa is a common nudibranch that can be encountered on our reefs.

Pteraeolidia ianthina is a solar-powered nudibranch that is synonymous with diving in Singapore waters. They are everywhere!

Jorunna funebris may be dressed in mourning colours, but it sure is cute!

The White-faced Pipefish is a recent new record for Singapore waters! Even though Singapore waters cover a seemingly small area, there is still lots for us to discover, which is why it’s always worth sharing and reporting anything strange that you might encounter. Learn more about this new record!

Flabellina rubrolineata is usually found feeding on hydroids.

Demon stingerfish (Inimicus sp.) are benthic fishes that live mainly on the bottom of mangrove swamps, seagrass beds and coral reefs. They have been recorded at depths between 5 and 450 meters! So-called because they look like ghouls but also because its enormous dorsal fin spines can inflict a very painful wound. As they commonly occur in shallow tidal areas, they risk being killed should a large animal step on them.

While most of the fish is dirt-coloured, Demon Stingerfish have brightly-coloured side pectorals that they use as a warning should they sense their cover has been blown. They are ambush predators that sit around and wait for unsuspecting fish to swim past them. Their lower two pectoral fin rays are detached from the rest of the fin and are used by the Demon Stingerfish to crawl along the seabed and sneak up on prey without stirring up the water. [1] There are two in this picture. Can you spot them?

This dive marks our last dive for 2014! Thank you so much for your support this year. Your curiosity and enthusiasm to dive and discover local waters with us has enabled us to discover even more about Singapore reefs and to share these discoveries with many non-divers during our school talks and public road shows. We were also very fortunate to have been able to contribute audio and visual content to this year’s Balik Pulau exhibition at the National Museum of Singapore! It was a lovely opportunity for Singapore’s reefs to be featured on a large and central platform in the middle of town! What a fantastic year it has been. We wouldn’t still be here without you. Happy holidays and see you again in 2015!

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