Semakau Inter-Tidal Walk on 1 Oct 2008

Seventy Fifth Discovery Posting

It was a Happy Children's Day as a group of nine fiddler crabs 'swam' (with the aid of a boat) to Semakau land-fill island, the last land fill we have in Singapore, for the first evening inter-tidal walk there (picture below).
After looking at ourselves at the bakau tree, we moved towards the seagrass meadows and being the lead crab, I had the responsibility to explain more about our first 'discovery' which we saw near the entrance of the seagrass meadows, a sand fish sea cucumber (picture below).
Discovery Note:
1. The popular Chinese name for sea cucumber is haishen, which means, roughly, ginseng of the sea.
2. They usually have a soft, wormlike body and can range from a few centimeters to even 90 cms in length!
3. The sandfish sea cucumber is among one of the species that is collected as the Chinese delicacy.
4. However, they must be properly processed before they are safe to eat as they contain toxins.
5. The sandfish sea cucumber feeds on detritus (dead or decaying organic matter).
6. More information can be found on http://www.wildsingapore.com/chekjawa/text/g623.htm

And as we walked across the seagrass meadows, we came across another sea cucumber, our second 'discovery', a synaptid sea cucumber (picture below).
Discovery Note:
1. The first thing to note about this sea cucumber is that it is one of the longest sea cucumbers in existance, it can grow up to a length of 3 meters!
2. They have a thin body wall and therefore more delicate than other sea cucumbers, so don't handle them with your hands if possible. =)
3. Like most sea cucumbers, they feed on detritus.
4. More information can be on http://www.wildsingapore.com/chekjawa/text/c621.htm

And before stepping out of the seagrass meadows, here are all the crabs (minus myself) in a group photo (picture below).
Forgot to take a photo of the sea stars and file snake we saw, so next up is a noble volute, third 'discovery'.

The bottom (picture below)The top where one can see its pretty shell (picture below)Discovery Note:
1. Volutes are carnivorous.
2. They prey on bivales, enveloping the victim completely with their foot forecing the bivalve to finally open from exhaustion and lack of oxygen.
3. Called the 'kilah' in Malay, the noble valoute is edible and people also often collect its attractive shell, thus it is now considered vulnerable.
4. More information can be found on http://www.wildsingapore.com/chekjawa/text/g422.htm

And of course, we also saw a relative, the swimming crab (picture below)! Fourth 'discovery'.
Discovery Note:
1. Swimming Crabs are among the few crabs which are fast and agile swimmers.
2. They usually swim sideways, like how all crabs move, but can also swim backwards and sometimes forwards too!
3. However, they don't swim all the time but usually dwell on the substrate they are at.
4. They have long pincers armed with sharp spines to snag fish, worms, clams, snails and other fast moving prey.
5. And when they are disturbed, they wave their pincers as a warning sign to tell you that they will not fear to give a 'good' pinch if one goes too close.
6. More information can be found on http://www.wildsingapore.com/chekjawa/text/c321.htm

Fifth 'discovery' is a great find by our seekers, a pair of sea horses (picture below)!
Discovery Note:
1. They are hard to find as they are well-camouflaged.
2. Do you know that a seahorse is actually a fish? Yes, it is, but instead of having scales, they have an inflexible armour of overlapping bony plates.
3. A seahorse cannot swim faster because it doesn't have tail fin and pelvic fins like other fishes, thus it is well-camouflaged. But they can make a short burst of speed if in danger.
4. They may look harmless, but they are actually quite voracious predators. It sits in wait and ambushes on any tiny animals that drifts or wander by.
5. They have a very simple digestive system (no stomach) thus they need to eat almost constantly. Baby sea horses are known to eat thousands of tiny shrimps in a day!
6. And of course, the most well-known fact of the sea horse is that the male can get 'pregnant', this is because the female seahorses lay eggs in the pouch of a male seahorse and it is in their where the eggs will be fertilized and then the male seahorse will carry them till the eggs hatch.
7. More information can be found on http://www.wildsingapore.com/chekjawa/text/c214.htm

And our sixth 'discovery' are the very 'cute' nudibranchs (pictures below).

Here's a Jorunna funebris (picture below). And a glossodoris atromarginata (picture below)Discovery Note:
1. 'Nudibranch' means 'naked gills'. The name comes from the flower-like gills found on the back of many nudibranchs. These nudibranchs use the gills to breathe.
2. Nudibranchs are related to snails. Little baby nudibranchs are born with shells, but they lose them when they become adults.
3. It doesn't mean that they are without defense. To protect themselves, some produce distasteful substances, toxins and even acids. They advertise this with bright warning colours. Others are camouflaged to match their surroundings.
4. By being small and flat, they can also easily hide in narrow places.
5. Most nudibranchs are carnivores, they eat immobile or small, slow-moving prey. Examples are sponges, ascidians, hard/soft corals, sea anemones, etc.
6. More information can be found on http://www.wildsingapore.com/chekjawa/text/c421.htm

And our seekers also found the 'stars' of our walks, the knobbly sea stars (picture below)!All crabs gathering for a photo with the stars (picture below).And as the night approached, many creatures came out to play, errr.. i mean prey.

Here's an octopus, our seventh 'discovery' (picture below) Discovery Note:
1. Octopuses are characterized by their eight arms (not tentacles), usually bearing suction cups.
2. They have a relative short life span, and some specials live for as little as six months.
3. They have three hearts! Two pump blood through each of their two gills, while the third pumps blood through the body.
4. They are also highly intelligent, probably more intelligent than any other order of invertebrates (any animal without a spinal column).
5. They are also able to change their body colour to camouflage themselves.
6. More information can be found on http://www.wildsingapore.com/chekjawa/text/c490.htm

Although we could not observe much stars under the sky due to the many clouds, we did have stars from the inter-tidal zone to light up the night (picture below). =)Would like to thank all the fiddler crabs for the wonderful company, we crabs rock! =P

Extra:
a) Read KS's blog on his entry about this trip.

Discovery @ Changi Beach on 20 Sep 2008

Seventy Fourth Discovery Posting:

Finally, the wait is over. The lower low tides of the day are finally here! And this means that I don't have to wake up at wee hours of the morning. =P

Yesterday late evening, with the company of E, G and I, we went on a exploration trip to Changi beach.

The first 'discovery' was a cool find. A flatfish (picture below)!
Discovery Note:
1. When a flatfish first hatches, it is a sole larve which looks like a larve of other 'normal' fish.
2. As the larva matures, it starts to swim on one side of its body, and one eyes and the mouth move to the upperside. This change may be completed within a span of five days.
3. It is interesting to note that the skeleton and digestive system also changes as the larva matures.
4. Once it is matured, the eyed-side (upperside) has camouflaging colours and patterns (as seen in the picture above) while the blind side (underside) tends to be paler.
5. The flatfish in its adult stage is an ambush predator. It usually lies in ambush just beneath the sediment or sand, with only its eyes sticking out waiting to snap up any small bottom-dwelling worms, bivalves, crabs and prawns which passes its ambush spot.
6. Information retrieved from http://www.wildsingapore.com/chekjawa/text/g213.htm. You may also read more about the flatfish on the same website.

The second 'discovery' of the night was a gong gong (picture below).
Discovery Note:
1. In Singapore, the gong-gong is a popular dish which is eaten steamed, fried with chilli or as fritters.
2. However, they are now uncommonly seen due to overcollection and habitat lost.
3. Interestingly, the gong=gong moves like a pole-vaulter.
4. It uses its claw-like operculum (as seen above) to dig into the substrate and pushes against it to 'hop' itself around.
5. Interestingly, they have a pair of eyes on stalks(as seen above) to help it see where it is and going.
6. Information retrieved from http://www.wildsingapore.com/chekjawa/text/g421.htm. You may also read more about the gong gong on the same website.

Walking around, we also managed to spot a few sea pens, here's one of them (picture below). Third 'discovery'.
Discovery Note:
1. Sea pens belong to the same group as soft corals and like soft corals, they are a group of polyps connected to one another in a colony.
2. While the polyps on hard/soft corals are alike, in a sea pen, there are different types of polyps connected to each other, each playing a different role.
3. First, there is the primary polyp, a central stalk which supports the whole colony. One role of the primary polyp (the bottom half) is anchoring the whole colony to the substrate and retracting the whole colony into the ground at low ride. It is interesting to note that the primary polyp is one individual animal.
4. Other individual animals emerge from the upper half of the primary polyp forming the 'feathers' on the central stalk. These are called secondary polyps or autozooids, they have stinging tenacles that filter feed when underwater.
5. There is also another kind of polyp, which is highly modified, called siphonozooids. Their role includes pumping water into the colony to keep it rigid and circulate water through the colony.
6. Information retrieved from http://www.wildsingapore.com/chekjawa/text/g520.htm. You may also read more about the sea pen from the same website.

Now fourth 'discovery' is something which I am not sure of its exact ID. But it looks a lot like a sea cucumber...hmm... can anyone help me with this (picture below)?
Discovery Note:
1. We spotted a number of them around buried amongst the seagrass. So they could be in season.

As we walked around, I lamented on why were there no sea stars, and as if hearing my complains, they soon pop out...hahaha.

Fifth 'discovery' is sand stars (picture below).
Discovery Note:
1. Sand stars, as the name suggest, are more often seen in sandy pools or sand banks.
2. They tend to be more active during night time while remaining buried in the sand during the day.
3. Sand stars have particularly long spines on the sides of their arms. These spines are harmless.
4. Sand stars are generally fast moving, in fact, one of the fastest moving seastar I have seen.
5. Unlike other sea stars which push out their stomachs to feed, they are one of the few species of sea stars whom swallow their prey whole.
6. They are known to be carnivores, their diet consists of bivales, snails and any small creatures which are in the sand.
7. Information retrieved from http://www.wildsingapore.com/chekjawa/text/s603.htm. You may also read more about the sea pen from the same website.

Sixth 'discovery' seems to be a biscuit star (picture below). I could not confirm its ID as I did not manage to get a good close up photo of its oral side.
The last organism which we took a load of time photographing was this stripped hermit crab (picture below). Seventh 'discovery'.Discovery Note:
1. Hermit crabs are not true crabs. What do I mean by that? Read on to find out...
2. True crabs have a hard, shorten abdomen which they fold under their hard shells (carapace) for protection.
3. Hermit crabs, on the other hand hand, have a soft, long abdomen and they don't have a hard shell to fold it under. So they insert and twist their abdomen into an empty shell for protection. So do not pull hermit crabs out their shells as you may tear its soft abdomen.
4. As a hermit crab grows bigger, its abdomen also grows bigger and it will have to find a bigger shell to accomdate this growth, or in other words, they 'upgrade' their 'homes', just like Singaporeans do.
5. The above point highlights the reason why we shouldn't pick seashells from the seashore like Sally =P.
6. Information retrieved from http://www.wildsingapore.com/chekjawa/text/s324.htm. You may also read more about the hermit crab in general from the same website.

Overall, it was an enjoyable night due to the many marine life seen, the sharing and company of friends and a walk under the stars. =)

Semakau Inter-Tidal Walk on 17 Aug 2008

Seventy Third Discovery Posting

Semakau Land-fill Island. An off shore island located south of 'mainland' Singapore where our incinerated rubbish and ones which cannot be incinerated (like: bricks, mostly construction waste) goes to.

But where exactly in Singapore is this island? Look at the map below and look out for the red circle to find it (picture below).

Picture above is from http://coralreef.nus.edu.sg/map.htm

Contrary to popular belief that Semakau Landfill would be another dirty and smelly landfill, the care put into the design and operational work at the landfill have ensured that the site is clean, free of smell and scenic. During construction, silt screens were installed to ensure that the corals were not affected during the reclamation works (from wikipedia).

Therefore, one can find corals and many other marine life at the inter-tidal area of Semakau. And this morning, together with a group of octopus-es (the group's name of the day) and E (co-guide for the morning), we 'swam' along the area to feed, ah-hem, I mean see the many marine life one can see there.

Anyway, our first 'discovery' of the morning was this dragon fish sea cucumber (picture below).
Discovery Note:
1. Sea cucumbers, like the sea star belong to a group of animals which have spiny skin, so when you feel them, it is most likely that you find that the touch is rough.
2. Also like sea stars, sea cucumbers use sea water to circulate their bodies. We (humans) use blood. Therefore, it is inadvisable to remove them from water for too long, as it might stress them.
3. And when sea cucumbers are stressed, they might either 'eject' sea water, white threads or even their internal organs.

The second 'discovery' of the day is a sunflower mushroom coral (picture below).
Discovery Note:
1. Most mushroom corals do not form colonies like most other corals and most mushroom coral is usually a single polyp.
2. Unlike most corals, most mushroom corals are attached to the reef only when they are small.
3. As larger individuals, they will detach themselves from the reef (if they had attached themselves to the reef) and live loose on the seafloor.

As the tide was the lowest level at the point of time when we just reach the inter-tidal area, we moved quickly towards the reef edge. And we saw the third 'discovery', a giant calm (picture below).
Discovery Note:
1. They are the largest living bivalve mollusc and also known as the bear's paw clam
2. They can weigh more than 227 kilograms and measure as much as 1.2 metres across, and have an average lifespan in the wild of 100 years or more.
3. An interesting symbiosis occurs between a unicellular green alga (Zooanthella ) and the clam. The algae live in the tissues of the clam's siphon and mantle; they are able to obtain the sunlight needed for photosynthesis because the clam lies with its valves opening upward and part of the thick, purple mantle extruding over the shell.
4. In addition, there are crystalloid vesicles on the mantle surface that let in sunlight, thus allowing the algae to live deep within the tissues. The clam uses the algae as a supplementary or perhaps even a major source of food.

Almost forgot to mention that along the way, octopus-es had a few close encounters with ourselves, the octopus. =P

All right, fourth 'discovery' is a great find by our hunter seekers, a cushion star (picture below)
Discovery Note:
1. This is more commonly seen at deeper waters at the sea bed, say around 10+ meters.
2. So the chance of one seeing a cushion star during diving is high compared to a inter-tidal walk.

Our hunter seekers, H and LK also managed to find us the star of the walk, the knobbly sea star, fifth 'discovery' (picture below)!
Discovery Note:
1. They get their name from the knobs they have.
2. Although most of them are mostly red or orange in colour, beige or brown coloured knobbly sea stars have been spotted before also.
3. Can you believe that a knobbly seastar might be larger than your face? It’s about 30cm across! (look at the pictures below to get an idea)

Traditional Group photos with the star (pictures below)!And nearby, I managed to spot another knobbly (picture below)!It was also quite a slug day. I don't mean a bad day but rather a day where we saw a number of different sea slugs.

Nudibranchs are the sixth 'discovery'!

Discodoris boholiensis (picture below)

Jorunna funebris (picture below)

A Chromodoris nudibranch (picture below). Discovery Note:
1. 'Nudibranch' means 'naked gills'. The name comes from the flower-like gills found on the back of many nudibranchs. These nudibranchs use the gills to breathe.
2. Nudibranchs are related to snails. Little baby nudibranchs are born with shells, but they lose them when they become adults.
3. It doesn't mean that they are without defense. To protect themselves, some produce distasteful substances, toxins and even acids. They advertise this with bright warning colours. Others are camouflaged to match their surroundings.
4. By being small and flat, they can also easily hide in narrow places.
5. Most nudibranchs are carnivores, they eat immobile or small, slow-moving prey. Examples are sponges, ascidians, hard/soft corals, sea anemones, etc.
6. Read more about nudibranchs on the online Chek Jawa Guidebook by clicking here.

We saw many other things, like a juvenile coastal horseshoe crab and flatworms, it's just that I didn't grab photos or good photos of them, or you could say I'm just lazy to blog about them... haha.

Anyway, thanks to all Octopus-es, you were a great group! =)

Extra:
a) Check out Manta's experience for the things his group saw on this trip.
b) Check out my co-guide of the day (E's blog) for more photos too.

Discovery @ Semakau on 3 Aug 2008

Seventy Second Discovery Posting:

Semakau land-fill island, a place where you can get great views of the sunset (pictures below)


Just over the weekend, we spent our night over at Semakau for some star gazing and most importantly, to explore a part of Semakau where we don't usually go to.

And for the first 'discovery' is something which I have never seen before, according to the RY and JH, this is the hell's fire anemone (picture below).
Discovery Note:
1. Like all anemones (which i know of), this anemone also has stinging cells, but...
2. This is called the hell's fire anemone as it is said to give a very painful sting.

And it's always great to see knobbly sea stars at Semakau, especially juvenile ones (pictures below)! Second 'discovery'! Discovery Note:
1. These sea stars can grow to as big as your face!
2. They are considered to be threaten due to the lost of habitat and probably collection.

The third 'discovery' of the day have to be the best discovery of them all for the morning, a Luidia maculata (picture below). This is my first time seeing this!Discovery Note:
1. This sea star sallows its food compared to eating with their stomachs out of their body for most other sea stars.

Fourth 'discovery' is a orange flatworm with white spots which I have never seen before also (picture below).Discovery Note:
1. Flatworms are hermaphrodite, which means a flatworm has both the male and female sex organs.
2. And certain species of flatworms engage in penis fencing, in which two individuals fight, trying to pierce the skin of the other with their penises; the first to succeed inseminates the other, which must then carry and nourish the eggs.

For fifth 'discovery', take a guess by looking at this picture to guess what it is (picture below)
What creature do you think this is (picture below)?Discovery Note:
1. This is a spider conch.
2. It moves around by 'pole-vaulting' itself (look at the picture above, it's in a state where it's about to 'pole-vault').
3. It's considered threaten due to habitat lost and over collection for its shell and as food.
4. Read more about them by clicking here.

I'll leave everyone with a beautiful sunrise from Semakau (picture below).Thanks to LK for organising the trip and everyone else for making this trip fun. It's just too bad we missed the firefiles as they seem to have moved to another spot. =)

Extra:
1) Check out tidechaser's blog entry on this trip.
2) Check out manta's experience for many different patterns of shells he photographed during this trip.

Discovery @ Cryrene on 21 July 2008

Seventy First Discovery Posting:

My second trip to Cyrene reef and I was knobbly eyed again like the first time round.

This is because Cyrene reef is the only known place in Singapore at the moment where the knobbly sea stars are commonly seen. A last count by Star Trackers recently showed that there is as much as 186 individuals on Cyrene! Read more about it on the Star Trackers' blog (http://startrackers.blogspot.com/).

And if you are wondering how a knobbly sea star looks like, here are 3 individuals (picture below)!
As this was my second trip, I decide to talk towards a part of the reef I didn't cover the last round and it was worth it as I came across possibly a juvenile cushion star (picture below)! First 'discovery'.
Flipping the cushion sea star around would give you a better idea that this is indeed a seastar (picture below).
Discovery Note:
1. They have this 'cute' or funny shape (however you wish to describe it) is probably because that such a shape would make it harder for its predators to take a bite at it.
2. Cushion sea stars are known to eat corals! Click on this link (here) to see an abstract of a paper which tells you more about it.

Of course, I also took many photos of the knobbly sea star I saw (pictures below). By the way, the ruler which you see in the photos is a 15cm ruler and it's there to aid Star Trackers for their project. Enjoy~

Well, Cyrene doesn't only have knobbly sea stars, you can also find common sea stars (picture below) and other kinds of sea stars if you are lucky. Anyway, second 'discovery' is the common sea stars.Discovery Note:
1. Their tube feet are interesting as they are used for walking, handle food as well as breathing, and probably to catch prey as well, talk about multi purpose!
2. Sea stars get stressed when out of water, this is because while we have blood circulating our bodies, they have sea water circulating their bodies.
3. They are not as common as their name suggests. This is due to past over-collection and habitat lost past and present. So don't take them away from their homes when you see them. =)
4. Some sea stars are predators that prey on worms, crustaceans and bivalves while some are known to eat decayed plant matters.
5. Many sea stars eat with their stomach outside their body. When doing this, their tube feet will pull the two shells of a bivalve apart. And while still attached to their prey’s body, they extend their stomach out through their mouths into the bivalve shell.

And also sand dollars which are related to the sea stars (picture below), third 'discovery'. Discovery Note:
1. Living sand dollars are coated in fine, harmless spines that made them very velvety.
2. The spines are movable and are used to dig into the sand or move around.
3. The dense layer of spines also helps to keep off sand and silt so there is a flow of oxygenated water across the body.

On Cyrene, I also saw the biggest piece of soft coral I have ever seen in Singapore's waters (picture below).Oh, if you are wondering what is the white thing in the picture. It's the 15cm I had with me. I placed it there to give everyone an idea how big is this piece of soft coral. Wow!
Cyrene is not only special because of the many knobbly sea stars you can see there. It is also special because it is a submerged reef (only exposed during low tide and is not connected to any land, thus amphibious landings are required) and it is located within the busy channels of our shipping lanes (near Jurong Island).

More about Cryene:
http://www.wildsingapore.com/places/cyrene.htm

Here's a picture to show you that it's near Jurong Island (picture below)And it's also not far from our city central (picture below). The background shows our central business district and also Sentosa. And the most interesting knobbly individual for the day had to be this (picture below).This (above) is also CK (a star trooper, not the one in Star Wars, but one from Star Trackers) favourite knobbly on Cryene.

And as we started to head back to our pick up point to go back, JH found a melibe nudibranch! A first sighting for me. Fourth 'discovery' (picture below)!Discovery Note:
1. This looks very different from all the other nudibranchs I've seen.
2. One major difference is that it has an expandable hood (you can see it in the picture above) which it used to grab small and possibly slow prey aka food.

Soon, it was time to head back before we get 'buried' in Singapore waters. =P (picture below)Thanks to Ria again for organising this trip and others for making this trip another interesting one too!

Extra:
a) If you are interested to visit Cyrene Reef, join in the blogging contest of "Let's go to Cyrene Reef", click here to find out more about it.
b) Check out Wildfilm's blog on the trip also on 21 July.
c) Wildfilm's blog again but for a trip on 22 July.
d) KS's blog for a trip to Cyrene on 22 July.