Sunday, July 18, 2010

Semakau Walk on 17 July 2010

It was pouring when we were on our way to Marina South Pier. The rain was so heavy, that the cab driver had to drive much slower than usual as visibility was really bad. And most unfortunately, when we turned into the Ayer Rajah Expressway, it was flooded, and we had to make a detour!

Fortunately, we still managed to reach the pier, and while it was still raining cats and dogs, we could see that it was less heavy. When we took the boat to Pulau Semakau, the rain had fortunately become a drizzle, and we managed to proceed with the guided walk.

I had a group of students from Raffles Girls' School, and our group name was "Hermit Crab". The students had to brave the rain walking for about half an hour to reach the entrance to the intertidal area. Some of the them decided not to use any rain gear as the rain was really light then.

However, it got heavier again when we were crossing the seagrass meadow, but that did not dampen our mood! :)

We saw quite a number of things despite the rain, but as the rain got heavy every now and then, I only managed to get a few decent photos.

Found this Moon Snail (Polinices mammilla) moving just beneath the surface of the sand. This snail is a fierce predator of smaller snails and clams. It has a huge foot with a wide mantle that it uses to wrap around its prey to suffocate them. If that doesn't work, it can also secrete an acid to soften the prey's shell, and use its radula (a tongue-like structure) to poke a hole through to feed on the meat inside.

Despite the rain, we saw lots of Sand-sifting Sea Stars (Archaster typicus). This sea star can burrow into the sand to escape from the rain or predators. It feeds on tiny decaying matter (called detritus) among the sand. To feed, it will push its stomach out of its mouth, which is in the middle of its underside. The stomach will "mopped" up its food and digestion will be done externally.

This Sandfish Sea Cucumber (Holothuria scabra) is another burrower. While this sea cucumber is edible, it must be properly processed to remove the toxins in it before it can be consumed. Interestingly, sea cucumbers breath through their anuses. Connected to the anus is a respiratory tree which is used for breathing.

We saw several octopuses (Octopus sp.) during this trip too! The octopus is one of the smartest invertebrates around, and is known to be able to get out of mazes and open jars to obtain food! This animal is made famous again recently due to the octopus, Paul, in Germany, which accurately predicted 8 World Cup games, including the finals!

This is a Funeral Nudibranch (Jorunna funebris). The name "nudibranch" refers to the flower-like gills on the back of most species. This little sea slug is poisonous, and it gets the poison from the sponges that it feeds on.

We also saw an Acanthazoon Flatworm (Acanthazoon sp.). This worm is so flat that it can easily slip into fine cracks among rocks to escape from predators or to seek for small animals to feed on.

Our hunter-seekers found us 2 Spider Conches (Lambis lambis). These huge snails are collected in some places for food. The top of the shell is usually covered with sediment which camouflages it, but turning it over will reveal the pretty colours on its underside.

Once again, we saw the resident juvenile Cushion Star (Culcita novaeguineae). It got its comon name from the fact that it's rather fat and looked like a little star-shaped cushion. This sea star feed on corals.

And talking about corals, we saw that there were still quite a number of bleached corals. Coral bleaching occurs when the algae living inside the corals leave their hosts or were expelled by the hosts. A healthy coral will usually be brownish in colour, as the algae living inside is a golden brown algae. The algae can photosynthesize and pass on some food to the coral in return for shelter and nutrients (waste matter from the corals). Bleached corals thus will lose a major source of nutrients, and may even die.

A little Noble Volute (Cymbiola nobilis) was also spotted. This snail feeds on smaller snails and clams.

Everyone was rather excited to see 3 Knobbly Sea Stars (Protoreaster nodosus). Semakau is one of the few places in Singapore where this huge sea star (can grow to about 35cm wide) can still be found in huge numbers.

And as usual, we had a group photo with the stars of the trip.

While the rain persisted throughout the trip, we were still very glad that it was not heavy (we actually did not have to use the rain gear sometimes), and most importantly, there was no lightning, or we would have to cancel the walk.

Certainly hope that the students enjoyed the trip :)

Saturday, July 17, 2010

Cyrene Reef 2010

The last time I visited Cyrene Reef was more than a year ago, and hence I was really excited to be back here again on 15 July 2010. Cyrene Reef lies in the middle of a very busy shipping channel, and we had to seek clearance from MPA before we could land on the reef.

We hired a yacht with a dinghy attached to it. When the boat was near the reef, we had to transfer to the dinghy as the water was too shallow. Here's some of us getting off the dinghy when we finally reached the reef.

One of the reasons why I liked Cyrene Reef so much was the abundant Knobbly Sea Stars (Protoreaster nodosus)!

And as the water was usually rather clear here, we could usually take clear wide-angle shots of many sea stars.

Here's a quick look at some of the various colours and patterns that the knobbly sea stars exhibited.

And some of them may have 4 or 6 arms, instead of the usual 5.

We saw many juvenile knobblies too! Here's a quick comparison of the sizes :P

We also saw several juvenile Pentaceraster mammillatus, and here's one of them.

They appeared to come in different colours.

Found this small brownish coloured one with missing arms. Not sure if this is a Pentaceraster or some kind of hybrid or whatever.

There was also this one which looked like a hybrid between a knobbly and a Pentaceraster.

Yet another one which looked like a Pentaeraster, but the knobs were not of a lighter colour like the rest.

I also saw a juvenile Cushion Star (Culcita novaeguineae).

And there were lots of Sand-sifting Sea Stars (Archaster typicus) on the sandy beach.

Related to the sea stars are the sand dollars (Arachnoides placenta). Both of them exhibit a penta-radial symmetry.

The white Salmacis Sea Urchins (Salmacis sp.) were in season, and we saw quite a number of them.

The Black Sea Cucumber (Holothuria leucospilota) was one of the more commonly seen sea cucumbers on our shores.

We also saw several Sandfish Sea Cucumber (Holothuria scabra), yet another often seen sea cucumber. This sea cucumber is the one usually served in the restaurant. They must be properly processed to remove the toxins before they can be eaten though.

Synaptid Sea Cucumbers were quite easily seen on Cyrene Reef too.

I was rather happy to see a juvenile Batfish (Platax sp.)! I had seen them many times on our shores, but this was the first time I managed to get a decent photo.

The others had better luck with slugs, while I only saw a pair of mating Bohol's Nudibranch (Discodoris boholiensis).

I saw the trails of a huge burrowing animals, and on uncovering the sand, I found a rather big Noble Volute (Cymbiola nobilis) that was about as long as my palm!

There were lots of unidentified Tube Anemones.

I saw 2 Long Tentacle Anemones (Macrodactyla doreensis) in the seagrass meadow.

There were several Haddon's Carpet Anemones (Stichodactyla haddoni), and some of them had Anemone Shrimps (Periclimenes brevicarpalis) on them.

Here's a closer look at the shrimp, but this time round, on a Giant Carpet Anemone (Stichodactyla gigantea).

We saw many Acorn Worms' casts on the sand, and this one we could still see part of the worm! This worm feeds on tiny decaying matter in the sand by swallowing the sand and digesting the edible bits.

Soon, tide was rising, and the dinghy picked us up to be transfered to the yacht.

It was a really fun and exciting trip. But quoting a friend who came on the trip with us, visiting these various intertidal areas really made us appreciate Pulau Semakau more. And why is that so? While most of the shores we had visited were beautiful in their own ways, none was as diverse as Pulau Semakau. There were just so many different habitats with their respective interesting flora and fauna at Semakau, and so far, I certainly had not come across any shore area in Singapore that could match it.

Tuesday, July 13, 2010

Recent Trip to Raffles Lighthouse

The RMBR Nature Guides went to Raffles Lighthouse earlier this morning to check out the intertidal life there. Not sure why, these days things appeared to be a lot quieter compared to last time, though we still saw a number of interesting stuff.

The intertidal reef was still tightly packed with different species of hard corals.

When we were here last month, we saw quite a number of the Acropora Corals (Acropora spp.) dripping some kind of mucus, like the above. Not sure why was that happening. We did not see any of these though.

The coral bleaching, however, was still quite bad. I will estimate about 50 percent of them bleached.

Even the solitary Mushroom Coral (Fungia sp.) above was bleached.

On some rocks, we found little cave coral.

The soft corals were probably bleaching worse than the hard corals though. Most of the ones I saw had turned white.

I found a few Tube Anemones in teh shallow lagoon.

Ying Wei spotted a Black Phyllid Nudibranch (Phyllidiella nigra). This nudibranch can secrete toxins into the surrounding water when it's stressed.

Robert found this pretty Bornella stellifer in the lagoon. This nudibranch supposedly feeds on hydroids.

This Bristle Worm (Eurythoe cf. complanata) was found stranded on the sand.

There were many octopuses here, and their ability to change their body colour was rather impressive.

Here's the same octopus which had turned a lighter tone.

This was my first time finding a Land Hermit Crab (Coenobita sp.) on this island!

I had seen this reddish hairy crab here before, but unfortunately still did not have the ID.

Marcus spotted this crab on a piece of wood floating on the water surface. He had checked the ID with the crab experts around, but again I can't remember what was it. Update: This is probably a Varuna litterata. It was spotted by Iris actually and Marcus was just kaypohing around. According to "A Guide to Seashore Life in Singapore", this crab can live in both fresh and saltwater. It can be found not only in streams and ponds far inland, but also in mangroves, the edge of the shore., and even on flotsam or floating seaweed, drifting with the currents.

I spotted this cute Acropora Crab (Trapezia sp.) among a colony of Acropora coral.

We also found several of these green -coloured shrimps with huge pincers living with many of the Acorpora colonies.

LK found a File Clam (Lima sp,), and later, I found another one.

We spotted two Arabian Cowries (Cypraea arabica) - one among the rocks, and another among the corals.

Not sure what these 3 Giant Top Shells (Trochus niloticus) were doing.

I saw a total of 4 Spider Conches (Lambis lambis)! I am sure there were probably quite a few more which we missed, since they were so well-camouflaged.

A Stonefish Sea Cucumber (Actinopyga lecanora) found by Hen.

We did not find this Juvenile Cushion Star (Culcita novaeguineae) during this trip, but on another trip we made here last month. However, since I did not blogged about that trip, decided to post it here :P

It was nice to be back on this shore, but somehow it just didn't appear to be as rich as before. Not sure what has caused the problem?