Sunday, May 31, 2009

Lovely Kusu with friends

On a Saturday morning, the last day of my 6-day consecutive low tide field trip season, I was out bring my church friends and Geraldine's friends to Kusu Island to show them the amazing creations of God in the marine habitat and coral reefs. Kusu Island is readily accessible from the city centre with a 15 minutes boat ride and one needs not to dive to experience corals and marine animals.

Kusu Island is also known as 'Turtle Island'. Some accounts say that the island originally comprised two portions which resembled a sea turtle with a larger part resembling the shell and a smaller portion the turtle's head emerging from the sea.

And all of us were very interested in knowing more about the history of this lovely small island.

I have not been to Kusu Island for almost two years and my previous trip was with Dr Daphne and the anemone team. Therefore, I was also as keen as the first timers in visiting the shores of Kusu.

What was the first star attraction that made all of us excited over?

It was the numerous number of the Common sea star (Archaster typicus) that seems to move and burrow quickly with its many tube feet. This is definitely not a clumsy animal as we witnessed and were amazed how the starfish flipped itself over from its underside to become upright.

The sandy lagoon is also where we can find many processed casts of the Acorn Worm (Class Enteropneusta). Acorn worms swallow mud and sand and process these for edible bits. At low tide, they stick out their rear ends at the surface and excrete coils of processed sediments which make up the processed cast.

Geraldine was working hard to trying to find some animals from tidal pools and put into containers for us to see. This is what we term as hunter seeking. After which, the animals were released to where they were originally found.

Kusu is probably the best southern shore with lots of huge sea anemones and many of these Haddon's carpet anemones (Stichodactyla haddoni) can be found in the sandy lagoon. Carpet anemones are animals with stinging tentacles. They sting fishes or crabs or other animals that crossed the anemone and then swallow their prey with the mouth at the centre.

Kusu Island was originally largely made up of living reef. In 1975, there was massive reclamation to make what Kusu Island is now today, with two swimming lagoons.

It is heartening that life has crept back into the swimming lagoon with lots of different types of corals.

And there were different types of corals in different shapes and colours.

I noticed a proliferation of the Blue coral (Heliopora coerulea) (bottom left of the collage) at Kusu as compared to other southern shores!

A couple of plate-like corals seen include the Ridged plate coral (Merulina sp.) and the Thin Disk corals (Turbinaria sp.).

There were also big colonies of the stunning Galaxy coral (Galaxea sp.) that look very starry and colourful underwater. Out of water, the polyps were all retracted within the coral skeleton, thus looking boring in colour.

Walking towards the other end of the swimming lagoon, one will find lots of branching corals!

They consist of thin branched corals that are further spaced apart....

To denser branching ones that are closely compacted and thicker. I supposed these branching corals should mostly be the Montipora corals (Montipora sp.). Sometimes, seahorses can be found within the branching corals but I was rather lazy to scrutinise properly. Who knows? They might just be out there. :P

There were also quite a number of the Frilled corallimorphs in the lagoon. Though their appearance and internal structure is similar to that of hard corals, corallimorphs do not produce a hard skeleton. Corallimorphs also lack long tentacles. Therefore, they are more related to sea anemones than hard corals despite having the word "coral" in their names. Just like horseshoe crab is not more related to spiders than true crabs.

There are also many different types of soft corals at the swimming lagoon including the Omelette leathery coral.

There are also Black-and-white leathery corals too!

So what are the differences between a soft coral and a hard coral? Under a microscope or probably a good eyesight, soft coral polyps have 8 (or multiple of 8) tentacles that are pinnate (branched or feathery) while hard coral polyps have with 6 (or multiple of 6) tentacles that are smooth and unbranched.

At the coral reef area, we see more colourful and bigger anemones like this purplish Magnificent anemone (Heteractis magnifica) which is probably most abundantly intertidally at Kusu!

Another anemone species will be this Giant carpet anemone (Stichodactyla gigantea) which made us all excited! Why?

It is because one can find the famous nemo in such anemones! We were all thrilled to see a living anemonefish swimming among the giant carpet anemone.

Nemos are made popular by the movie Finding Nemo. However, the species we have in Singapore, the False clown anemonefish (Amphiprion ocellaris) is not the Clown anemonefish (Amphiprion percula) depicted in the movie. The latter lacks the black bands on the top edge of the dorsal fin. The natural distribution of these two species of anemonefishes do not overlap.

Nevertheless, non-scientists would usually get all hyped up when seeing the False clown anemonefish, without consideration whether it has black bands or not. Heehee.

As I was looking around further, I saw this interesting Decorator or Velcro crab (Camposcia retusa) that only seems to have some seaweed on its body. Yet it is still very well camouflaged. From far, if the crab is not moving, I guess none of us would have noticed this master of disguise.

Later on, I brought some of us down to another part of the shore which is bit more rocky but yet very colourful!

The reason for being very colourful must be due to the overwhelming presence of Zoanthids or colonial anemones (Order Zoanthidea). The greenish crop is actually the Coin green seaweed (Halimeda sp.).

Some zoanthids contain powerful toxins to protect themselves against predators. The most toxic marine poison, palytoxin, was discovered in a zoanthid wher minute amounts can paralyse and even kill.

Yet on the other hand, palytoxin has been used to better understand how our body works and may provide better treatment of hypertension, heart disease and other disorders. Interesting isn't it? These animals are like resources, waiting for us to discover!

While flipping rocks to look for interesting organisms, which we later found a flatworm, crabs, snails etc, there was this stunning red sponge as well! And a brittlestar was found within it!

This blue sponge was found growing together with greenish faviid corals, thus making this shore very colourful.

This yet another bluish looking creature on the shore is not a sponge nor ascidians. They are corals!

These are probably the Broad feathery soft coral! In whether, their identity as corals was a giveaway from their polyps. This bluish soft coral just looks so cool to us. :-)

Another soft coral at this rocky shore will be the cauliflower-lookalike, the Asparagus flowery soft coral.

This pretty snail could probably be drill, a member of Family Muricidae.

Nearing towards the end of the trip, the dark clouds came and showered the whole place. Thank God that He granted us good weather till almost the very end. And it was just a passing shower.

And we took a group photo together near the lagoon before we called it a day. As you can see, the background shows skyscrapers from our city centre which is very near to our natural coral reefs.

Apologies for a smiley face on one of my friend who is too shy to want to appear on photos to be published anyway. :P

In all, we had a great time together! All of my friends were first timers except for Geraldine and they have thoroughly enjoyed being outdoors looking at marine life in their wild natural setting and getting marvelled by God's wonderful creations.

All too soon, it's time to leave the island. See you next time Kusu!

Thank you my friends for giving me the privilege to show you to Singapore's true marine life other than the Underwater world. Hope you all enjoyed it and probably we'll meet at the shores again to marvel at these creatures.

Saturday, May 30, 2009

My first St John's intertidal guided walk

It has been some time since I've visited the Tanjong Hakim shore of St John's Island. This time, I am visiting it with a group of new friends through my first St John's Island guiding of the intertidal area.

It was a scorching bright sunny morning and we first headed out to the sandy lagoon.

And these are the friends I was referring to. A group of friendly and interesting people who are very interested in the marine life of Singapore. Melissa (in yellow) was formerly a marine biologist!

We began the walk from the high shore to the lower shore zonation.

And within the sandy lagoon, we realized that it is home to many Common sea star (Archaster typicus)! And we witnessed stars with even four and six arms!

Interesting facts about this starfish species are that it can eject its stomach to feed and that they have the ability to regenerate their arm if there is a sublethal arm loss which can be caused by predation.

There were quite a number of small crab finds including the Pebble crab (Family Leucosiidae) on the left and the Soldier crab (Dotilla sp.). In addition, there are also several Sand bubbler crabs (Scopimera sp.) and Orange fiddler crabs (Uca vocans).

A pair of the Oval moon snails (Polinices mammatus) was also found by our hunter seekers.

Moon snails are fierce predators, feeding on bivalves and snails. A moon snail wraps its huge body around the hapless prey to suffocate it. If this fails, it has a gland at the tip of its proboscis that secretes an acid to soften the victim's shell. With some help from its radula, a hole is created.

After looking at the special find of the Sundial snail, some anemone-looking tentacles were found nearby. Could this be a juvenile Bulb-tentacled sea anemone (Entacmaea quadricolor)?

I later went on to talk about our natural oysters. Oysters are well known to be delicacies in seafood. However, people also associate them with beautiful pearls and may try to pry them open to find them in the wild. However, these pearls are generally not found in nature.

Most pearls we see in the market are cultured and produced on farms. A plastic bead is inserted under stringent conditions, into special bivalves and removed when a thin layer of mother-of-pearl is secreted by the animal. Natural pearls tend to be mishappen and worthless and only occur when a bit of dirt accidentally enters the oyster, which doesn't happen often. Therefore, please don't needlessly kill wild oysters out of curiosity.

The next part of our walk is down to the natural coral fringing reef. The tide looks low!

Before we proceeded to the lower shore, there was a Land hermit crab (Coenobita sp.) found very high up. If you are wondering why, it is because the land hermit crab is so well adapted to life out of water that it will drown if kept underwater! It has special gill chambers that act as lungs.

We went on to talk about how these land hermit crabs are being sold in shopping centres as pets at high prices. This is definitely one of the many threats including that these poor hermits have to endure. For me, I love to see animals happy living in their natural homes. Who likes to be jailed? Do you? Animals, as living creatures like humans, also have the right to live where they originally belong to.

Most people have the impression that seaweed is not in the tube shaped form but this White-stemmed seaweed (Neomeris sp.) is indeed a seaweed. Clusters of these seaweed are usually found on rocks and coral rubble.

A Fireband murex snail (Chicoreus torrefactus) was also sighted! Like the moon snail it can soften the shell of its victim with a weak acid secreted by a special gland on the underside of its foot. Elsewhere, this snail is frequently collected for food and shellcraft. In some localities, populations have been greatly reduced because of over collecting.

The spider conch (Lambis lambis) is definitely an interesting animal! Not only is its pattern being pretty, this conch has two long eye stalks that can peer at all of us. In additon, it has a long muscular foot that can flip itself back and we were marvelled at how it does this!

Of course, coral reefs of the St John's definitely has hard corals like this Pore coral (Porites sp.) that is commonly found here.

Another common coral of this shore will be the Blue coral (Heliopora coerulea). But the blue coral is more related to soft corals instead.

Soft corals of St John's include this creepy looking soft coral that we named as the Dead man's finger. Indeed, it looks like many dead men fingers are coming out from the rock. They look bizzare!

More soft corals abound at the deeper waters.

Sadly, our impression of St John's shore seems to be that the hard corals are doing poorly as compared to the past. Could it be due to the landslides? I reckon it be due to the change in hydrodynamics after the bridge that links to Lazarus has been built. Hydrodynamics of the sea is very important in both providing nutrients to the corals and also provide spawnings of new corals from reef sources elsewhere.

There were a number of flatworms to us to see thanks to the hardwork of our hunter seekers!
The Persian carpet flatworm (Pseudobiceros bedfordi) is one that can eat ascidians and other small crustaceans.

Other flatworms include the Orange-edged black flatworm (Pseudobiceros uniarborensis) on the left and the electrifying blue-in-colour yet rarely seen Red-tipped flatworm (Pseudoceros bifurcus)!

Though the rocky shore may look lifeless, most living creatures are actually hiding beneath rocks to prevent dessication and heat stress. So I overturned some rocks to show how life teems at the underside of the rock without themselves being squashed.

Aha, first we saw a Beige flatworm that sort of resembles mobile phlegm. :P

Then there were also creatures like a sponge, a sea cucumber, snails, small clams and ascidians clinging onto the underside of the rock. We later saw lots of Purple under-a-stone sea cucumbers under a particular rock! It was most fascinating.

How come there seems to be an aerial photograph of many volcanoes?

No lah, it is actually a normal photo of lots of Volcano barnacles (Tetraclita sp.) covered in green algae. But it is such a lovely piece of natural art, don't you agree with me too?

Before we left the rocky shore at the end of the walk, we took another group photo. Take nothing but photographs, leave nothing but footprints.

Thank you my group "Mangroves" for being such a nice group to share the marine life of St John's with.

Parts of St John's natural rocky shores are as charming as before. Such coastal landforms are now rare in Singapore.

However, it was sad to see huge portions of the cliff being cemented to prevent further landslides. I didn't have the heart to show you all the cemented cliff photo but landslides are usually caused by human modifications of the biophysical conditions, which is existing at St John's higher up above the cliffs.

Thus, it is crucial that development of all sorts should be done in due respect and knowledge of how nature works. If done sensitively, development and conservation of nature can coexist just like Semakau landfill. I'm not too sure if it applies to St John's as well given so many threats it is currently facing.

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