Tuesday, April 29, 2008

Chek Jawa Walk with Fren's Frens

Went to Chek Jawa to help with the public walk last Sunday, and it so happened my friend Shuyun managed to get some slots for the walk, and so I volunteered to guide her and her friends around.

It was a really hot day, but fortunately we still managed to see quite a few things though many animals were probably hiding from the heat. Here are some of the animals we saw...

Spotted this elbow crab hiding among the seagrass. Can you guess why it's called an elbow crab? :)

There were lots of sand dollars, ironically, on the sand bank.

Jellyfish were certainly in season, and we had been seeing them on both our northern and southern shores. Understand some of my friends were stung by them recently while they were diving in local waters, and it was really painful.

I was really glad to find the resident carpet anemone on the sand bar. Despite the heavy rainfall last week, it was still around and looks rather healthy (marine creatures usually get very stressed if there's too much fresh water).

This is a sand collar - the egg capsules of a moon snail.

This was the first time I saw an orange mud crab during a public walk! Actually, the last time I saw a mud crab was probably in the restaurant...

Our hunter-seekers found us this really small octopus.

As usual, there were lots of orange striped hermit crabs around.

We saw a few sea cucumbers during the walk. The one above is one which I still haven't got the ID proper.

This is a sandfish sea cucumber. It's also the one you usually get at Chinese restaurants. However, they must be properly treated to remove the toxins before they can be eaten.

Not really sure what this is. It's rather flat, so initially I thought it could be a flatworm. However, taking a closer look, I saw 2 tentacle-like structures sticking out of its front end, and they really look like rhinophores. So I guess it could also be a slug.

This cute little animals is called a ball sea cucumber.

Fortunately, we managed to find a few sea stars even though it was already rather late in the morning, and the sun was scorching hot.

Other than the mud crab we saw earlier, we also saw another common edible crab - the flower crab! This one has barnacles growing all over it though, and doesn't really look well.

At the tip of the sand bar, we decided to take a group photo.

And sigh... This is what you get when you are in the first row... :P

After the intertidal walk, we got back onto the boardwalk again and went to take a look at the mangroves.

There were lots of nipah palm growing by the side of the boardwalk. This one happened to be flowering, and there were lots of insects flying around it. Nipah palm's fruit is where you get your attap chee in your ice kacang.

This little monitor lizard quickly crawled away when it saw us approaching.

Finally, these are the fitter ones who managed to get on top of the Jejawi Tower!

Well, on the wy it was a really nice trip despite the ultra hot weather. And Shuyun's friends were a really enthusiastic and fun-loving bunch. Thanks everyone for making this trip such an enjoyable one! :)

Sunday, April 27, 2008

Differentiating between Diadema setosum, Diadema savignyi & Echinothrix calamaris

Some of you may have read the heated discussion over the ID of the sea urchins found on Cyrene Reef on the Wildfilm's blog. Dr David Lane who visited Singapore recently told some of the guides that not all sea urchins with an orange anal ring are Diadema setosum, and one of the specimens spotted which has black-and-white stripes on its spines, and has smaller blue spines could be Echinothrix calamaris, while others with blue lines on the test could be Diadema savigyni.

On reading the first blog entry by Budak, I noticed that the specimen in his blog look dramatically different from the previous specimens of Echinothrix calamaris that I have seen. Most importantly from what I've read on several online guides, the orange anal ring is indeed a distinguishing feature for Diadema setosum.

For the second entry by Ria, I remembered I've read that while both Diadema setosum and Diadema savigyni looks rather similar, the former has the orange anal ring with 5 white spots on its test. Coincidently, the book I read was published by Dr Lane and another echinoderm expert.

With the various discrepancies, I see the need to perhaps seek the opinion of other experts to clarify things, though various other volunteers disagree.

While doing my research online, I found a study on the taxonomic significance of test morphology in the echinoid genera Diadema and Echinothrix published in the year 2006. Since the study is fairly recent, and to be published in a journal means it had been scrutinised by other experts in the field, I personally feel this paper is sufficient to shed some light on the confusion on the various IDs.

Update: I just realised many volunteers, including some experienced ones, had thought that the test refers to the skeleton of a dead urchin without spines. Actually, the test refers to the globular shell of the the sea urchin, whether it is alive or not. And the study is conducted on both living and denuded specimens. And one thing for certain, if the study has really been conducted on dead sea urchin tests, then the colours will already be all gone, and they won't be able to even conduct this study in the first place. Just also to clarify that Diadema sea urchins are some of the easiest species to identify in the field, and in fact, from photos if taken correctly to show the anal cone, test other other key features.

According to the paper, the key to identifying the 3 sea urchins and some of their characteristics are:

1. Diadema setosum
Key: Orange anal ring. Blue/green “spot” markings on genital plates.
Other characteristics: Lines of blue spots on test, no apical ring, white spot marking (day and night), no platelets on anal cone.
An example of this species showing the characteristics above is the one which Dr Lane said could be a Diadema savigyni in the cyrene reef blog.

2. Diadema savigyni
Key: Test distinctly circular not rounded pentagonal when viewed aborally. Test (in living echinoids) distinctly black, with a bold pattern of iridophores down the mid-lines of the interambulacra.
Other characteristics: Bold blue lines on test, bold blue apical ring, white spot marking typically at night only while showing small red/brown spot markings during the day, no platelets on anal cone.
An example of this species showing the characteristics above can be found at Poppe Images. Update: Noticed that the link above is inactive. So here's another example from one of my blog entries.

3. Echinothrix calamaris
Key: Ambulacra prominently raised aborally. Genital plates significantly longer than wide (brown colour morph). Ambulacra only slightly raised aborally. Genital plates not significantly longer than wide (white colour morph)
Other characteristics: Green bands on test, periproct is large and brown with white platelets.
An example of this species can be found on my blog.

You may view the entire paper here.

Personally, I never blindly believe in what an expert says, but always verify with a few sources. If you can find the info in a published journal, it's even better since it would have had several peer reviews before it's published - as good as you have consulted with several experts. While this may not mean the outcome will be 100 percent accurate, at least I minimise the chances of learning the wrong things. And also, the experts are not always the first to say that they could be wrong, as we must remember that the experts are humans too, and humans do, and will, make mistakes. The experts know that, and that's why they always have peer review, but unfortunately many lay people assume otherwise.

Asking question is the heart of Science. It's always beneficial to ask what if the one raising the question could be right and do some research on it.

Maybe some people may wonder why I bother to try to find out the correct IDs and correct other people's blog. Many of the volunteer bloggers I know would have probably gotten at least a few emails from me for wrong IDs. And I have received several emails myself from peers who noticed mistakes in my blogs. Perhaps it's because I'm a webmaster by profession, and I'm more sensitive to the power of the Internet. It has a multiplying effect. The people who read the wrong info will just pass it on, and worse still if the reader is a nature guide who may spread the wrong info to his participants, and blogs the wrong info to spread to whoever reading the blog entry.

I'm really no expert myself, so I'm also thankful to those who have corrected any mistakes on my blog, and even more thankful that there are so many scientific sites around these days for me to verify any information that I wish to clarify :)

Saturday, April 26, 2008

Semakau Landfill on a Sunny Day

Well, anything is better than a rainy day, even though I have admit it really got burning hot towards the end of our walk.

Anyway, I was out on Semakau Landfill with a group of enthusiastic visitors again today! And our group name is Spider Conch!

The sun rise was simply stunning when we were on the boat! And YES! We got to depart from Marina South Pier today since we had more participants and could get a bigger boat.

We soon reach Semakau Landfill, and unfortunately, we still have to walk from the jetty to the intertidal area again today. Luckily, it still wasn't very hot then :P

As usual, my visitors asked me what are the brown and bluish stuff near the seagrass meadow, and were rather surprised to hear that they were sponges (Phylum Porifera)! Well, guess this group comprised mostly adults who didn't watch SpongeBob SquarePants. Sponges are simple marine animals that feed on tiny organic particles and plankton in the water.

As usual, I took a group shot of the gang crossing the "river" of seagrasses.

Like yesterday, we found lots of common sea stars (Archaster typicus) in the pseudo-mating position. The one on top was the male, while the one below was the female. When the tide came in, they would release sperm and eggs into the water for external fertilisation.

In the distance, we could see lots of grey heron (Ardea cinerea), probably hunting for little marine animals stranded in the tidal pools during low tide.

We didn't managed to find a seahorse today, but fortunately we found its relative, a pipefish (Syngnathidae) instead.

The noble volute (Cymbiola nobilis) is a pretty sea snail which feed on other snails and clams.

We had been seeing their capsules, and sometimes the adult snails as well, but this was the first time I saw a spiral melongena (Pugilina cochlidium) in the process of laying eggs at Semakau Landfill!

These sea slugs are called nudibranchs (Chromodoris lineolata). "Nudibranch" means "naked gills", referring to the flower-like gills on the back of the slug.

This feathery thing is actually a worm that lives in a tube! Called fanworm (probably Sabellastarte indica), this animal uses the feather-like structures to collect any edible particles in the water.

Many of my visitors were really excited to see this beautiful ocellated sea cucumber (Stichopus ocellatus). This is a rather common sea cucumber on Semakau.

Another type of nudibranch we saw was the polka dot nudibranch (Jorunna funebris). This nudibranch feeds on sponges.

As tide was a little higher today, we had problem finding the knobbly sea star (Protoreaster nodosus) initially. I had to wade out quite a bit before I managed to spot one. And of course, we just had to take the traditional group shot with this pretty sea star!

Here's a closer look at the knobbly sea star.

Semakau is also a great place to see huge colonies of hard corals. The above is a boulder coral (Family Favidae). These corals are colonial animals, and every hole you see in the brown structure above contains one coral animal (called a polyp)!

Yet another type of nudibranch we saw was the Gymnodoris rubropapulosa. This sea slug actually feed on other sea slugs, including other nudibranchs of the same species!

Found this scallop (Chlamys sp.) in a tidal pool. Scallops can swim by opening and closing their shells, just like the way you see in Chinese opera (if you are from my generation or older, that is, then you may have seen this before).

This is the species of sea cucumber that is usually eaten during important occasions by the Chinese. It's called sandfish (Holothuria scabra) because they are usually found on a sandy substrate and they can burrow into the sand.

Found this sand collar, which is actually the egg capsules of a sea snail called the moon snail.

And near the sand collar, I saw a trail on the sand, digging into the sand at the end of the trail revealed a pretty moon snail with a very smooth shell. This snail eats other smaller snails! It has a foot which can get bloated up with water, and it will wrap its foot around its prey to try to suffocate it. It can also secrete an acidic liquid to soften the shell of its prey, and use its radula (something like a tongue) to slowly create a hole on on the shell of its prey, so that it can feed on the latter while they are still in their shells!

Soon, its time to go, and on the way back, we stopped by the huge mangrove tree to take a look at the fiddler crabs. The above is a porcelain fiddler crab (Uca annulipes). Only the male crabs have one enlarged claw, and they use them to attract the female crabs! They can only feed with their smaller claws though, as the enlarged claws are often too big to be used for feeding. Fiddler crabs feed on detritus, which are basically tiny bits of organic particles.

And after the fiddler crabs, it's time to head back for the landfill tour followed by a quick video presentation showing how the landfill operates, before we took our boat ride back to main land.

While the day was rather hot sunny, I must say that it was a really wonderful walk. Special thanks to my visitors for being such a wonderful audience despite the long walking distance and the scorching sun! :)

Friday, April 25, 2008

Semakau Walk with International Students

Today, I have a group of international students with me at Semakau Landfill. As the group is rather small, we departed from West Coast Pier again. Here's a quick recap of the trip.

We had to walk from the old Pulau Sakeng to Pulau Semakau as it was too early for the NEA staff to drive us there. Fortunately, the sky was covered by the clouds and it was quite cooling.

As we entered the secondary forest, LK spotted this praying mantis on the sea almond tree.

Many kids these days know that sponges are animals that can be found in the sea, thanks to the cartoon "SpongeBob SquarePants". And here's a pretty sponge we saw before we entered the seagrass meadow.

And of course, I always remember to take a fun shot of my visitors walking across the seagrass meadow :)

The seagrass meadow is an important nursery ground for many marine organisms, as there are lots of hiding places and food. Many of the seafood we eat spend part of their life living among the seagrasses.

One of the first animals we saw after crossing the seagrass meadow is this cute little orange striped hermit crab (Clibanarius infraspinatus). Unlike true crabs, a hermit crab has a soft abdomen, and thus, need to hide it in a shell for protection. So if you are out there on the shores, please don't pick up any shells, or you may be depriving some hermit crabs of their protective shells, and they will have to run around naked! That makes them very vulnerable to predators.

We also saw lots of common sea star (Archaster typicus), and some of them were getting ready for some hot action.

We found this scallop (Chlamys sp.) near the common sea stars.

Our hunter seekers also found us this pretty polka dot nudibranch (Jorunna fundebris). It is a sea slug that feed on sponges.

While we were trying to search for the knobbly sea star, my group spotted this sandfish sea cucumber (Holothuria scabra) instead. It is edible, but must be properly treated before it can be eaten.

This type of jellyfish is apparently in season these days, and I've been seeing them both on our northern and southern shores. Even as out boat is arriving at the jetty earlier, we could see many of them swimming in the water.

At this point, tide was rising and we still couldn't find the knobbly sea star. And just when we decided to head back, JL shouted to us. And YES! He found it!

So finally, we mananged to take the traditional group shot with the knobbly sea star (Protoreaster nodosus)!

Hopefully we can find it as well tomorrow :)