Underwater Garden at Tuas

Yesterday, the RMBR Nature Guides were back at Tuas to check out the intertidal area.


What I like best about Tuas was the many soft corals and zoanthids. They were everywhere, just like flowers in a garden!


Some of the soft corals look really cute, like little puff balls.


Others look like a bunch of little flowers.


Apart from the softies, we have hard corals there too. The above was quite a huge colony - about 80m wide.


Many sea anemones, yet another kind flower-like animals, were spotted. The above unidentified sea anemone looks just like a glass flower! We saw several huge carpet anemones too.


There were a few red sea pens too, adding more colours to the already very colourful "underwater garden".


Just as brilliantly coloured were the sea fans, and Tuas has many of them.


Some of the sea fan colonies were really huge - almost a metre wide and tall!


The closely related sea whips we saw were not that colourful though.


These branch-like stuff were no sea fans but hydroids. They can give really painful stings, leaving scars that take a long time to heal.


Another animal which gives painful stings is this jellyfish.


We noticed a shrimp scampering around it, even among its tentacles!


Another shrimp-like animal is this one. Looks like a ghost shrimp to me, though the colour is not as bright as the ones I have seen before.


LK found this very pretty blue shrimp, my first time seeing it!


We found lots of these Laganum Sand Dollars (Laganum depressum), with many of them just below the sand surface.


This Rock Star (Asterina coronata) was the only sea star we found.


The Pink Thorny Sea Cucumber (Colochirus quadrangularis) can be found among the seaweed.


There were lots of Glassy Bubble Shells (Haminoea sp.) on the muddy-sandy substrate.


The Tiger Moon Snail (Natica tigrina) is supposed to be a fierce predator of other shells. Wonder if it feeds on bubble shell?


There were lots of Sea Squirts (Polycarpa sp.) at Tuas too.

Special thanks to Sheryl and Helen from Schering Plough for helping with the coordination work :)

Beautiful Tuas

The last time I went to the Tuas intertidal area was more than a year. Thanks to Schering Plough, we were able to make the visit again to check out the shore there on 13 Jan 2009.


Immediately when we walked out to the sandy shore, we saw many sand stars (Astropecten sp.) lying on the reddish sand. These sea stars feed on small seashells, and their presence suggest a good population of seashells too. To feed, they actually swallow the live seashell whole, digest the meat, then spit out the hard shells.


Getting into the shallow waters, the many colonies of soft corals appear before us, spreading out like flowering bushes in an underwater garden. Unfortunately there was a lot of sediment in the water, and thus most of them were covered with a coat of silt.


And in this underwater garden, there were lots of zoanthids too, covering several parts of the shore like floor mats. Sometimes also called colonial anemones, they are related to corals and sea anemones, and possess tentacles with stinging cells to hunt for little microscopic animals or tiny organic particles suspended in the water.


It would have been difficult for us to spot this velcro crab (Camposcia retusa) if it was among the sponges, but unfortunately it was on the sand. This crab plants all kinds of things onto it, dead or alive, such as stones, sponges, ascidians, and algae.


Also a master of camouflage was this spotted-tail frogfish (Lophiocharon trisignatus). By blending so well into its environment, it can hide effectively from its predators, and at the same time, ambush its prey.


It was certainly a pleasant surprise to find this stinging anemone (Family Aliciidae), which I have also seen at Semakau and Changi. It supposedly gives really painful stings.


Interestingly, after sliding around for a while, it started climbing onto a little rock! It stuck its oral disc onto a higher spot on the rock, and then started pulling the entire body column up the rock.


There were several solitary ascidians (Polycarpa sp.) among the coin seaweed (Halimeda sp.). It's rather hard for some to believe that this blob is actually more closely related to us vertebrates than things that can moves a lot like crabs and sea stars. Ascidian are also from the phylum Chordata like us.


Also hiding among the seaweed was this filefish, probably a Monacanthus chinensis.


Several pink thorny sea cucumber (Colochirus quadrangularis) were also spotted. Seems like they were in season at the moment, and we had also seen many them at Changi.


On many of the smooth encrusting sponges, we saw lots of little synaptid sea cucumbers.


One of the really exciting find of the day was this melibe nudibranch (Melibe viridis). Before this we have only seen it on Semakau and Cyrene Reef. This nudibranch supposedly feeds on crustaceans like little crabs and shrimps, but interestingly, we actually saw it being attacked by a hairy crab that night! The hairy crab grabbed it with both claws, like it was hugging it and dragged it into a hole. And all of a suddenly, we saw some mucus-like substances flowing out of the hole! Seems like the nudibranch had released some chemicals. The crab apparently let go, and I was able to get the nudibranch out of the hole with my chopsticks, and it started swimming away by wriggling its long body before settling down a short distance away. This was the first time I actually witness chemical warfare in nudibranchs against a predator! Really exciting!


We also saw a few other more commonly seen nudibranchs, such as this Dendrodoris denisoni.


This bumpy little creature is also a nudibranch, probably a Actinocyclus sp. It was sometimes mistaken to be a marine pulmonate slug (Family Onchididae) due to its bumpy appearance. However, you don't usually find the latter underwater, since it's a pulmonate slug that breathe air with simple lungs, though some species are known to be able to survive for short periods of time underwater by breathing through their skin or gill-like papillae.


Somehow this shore has lots of sponge crabs (Cryptodromia sp.), and we found quite a number of them.


On our way back when the tide was rising, we had another special find - an eight-armed sea star (Luidia maculata)! While this species is rather widely distributed in Singapore, and we have bascially seen it on many of our northern shores, eastern shores, and even southern shores like Pulau Semakau, this was the first time we found it on our western shore!

While Tuas is not exactly a very big area, it certainly has lots of surprises, and I'm certainly keen to visit it again, perhaps on a daytime tide the next time round!

Nature Workshop with Dunman High

I conducted a nature workshop recently for some Dunman High students, and here's a quick account of the experience we shared.

On the first day, I brought them to Pulau Ubin, and gave them a guided walk along the Sensory Trail and also Chek Jawa Boardwalk. Unfortunately, I forgot to bring my camera that day, and thus have no photos to share here.

On the second day, we went to Tuas grassland in the morning.


It was something new for most of the students, I guess. Everybody's feet had to get wet as Tuas is usually water-logged.


Many pretty plants and animals live in Tuas, including the ground orchid in the photo and the little crab spider partially hidden.


Tuas grassland is also where you'll find Singapore's smallest dragonfly - the pygmy dragon.


Once everyone got into water, we decided to have a group photo.


And here's a more energetic-looking one... :P


Here's another group photo taken among the complex network of sea morning glory vines.

In the afternoon, we went to Bukit Timah Hill.


There are many long-tail macaques just near the entrance to the reserve.


But what got us really excited was this monitor lizard eating a huge centipede. The centipede was still alive and struggling when we saw the monitor lizard.


There were lots of cicadas making loud screeching sounds in the forest, and this time round, I managed to catch one to show the students their underside.

On the last day, we went Semakau Landfill.


We had to cross a seagrass lagoon to reach the reef area.


In the seagrass lagoon, I found this huge synaptid sea cucumber which is probably more than 2m long.


Yet anther sea cucumber we found was this stonefish sea cucumber.


There were lots of sand-sifting sea stars, some of them getting really to perform external fertilisation.


We really wonder what happen to this file snake. Its head was stuck in a hole.


Fortunately, we managed to find the knobbly sea star and took some quick group photos.


Soon, tide was rising and on heading back to the mangrove area, I spotted this little horseshoe crab.

On the whole, I have to say the students were great and we learned a lot of things from each other. Looking forward to see some of them joining as nature volunteers in future!