Semakau Inter-Tidal Walk on 3rd June 2007

Sixth Discovery Posting:

(Entry@5th June 2007: With help from Ron, i've managed to ID one of sea cucumbers that was 'discovered'.)

It have been almost a full month i've not stepped on Semakau Land fill island for an inter-tidal walk and the first thing that greeted everyone when we stepped on Semakau on this clear morning was this beautiful sunrise (picture below)

And as we turned in the direction of the inter-tidal area, a rainbow was spotted amongst the clouds (picture below). Can you spot the rainbow? Hint: Look at the middle of the picture.
Note:
I'm going to list this as a first 'discovery' as it was the first time i saw a rainbow on Semakau.
Discovery Note (How is a rainbow formed?):
1. When sunlight enters a raindrop in the air, the light splits into a multitude of colors.
2. This light then reflects off the back of the raindrop and re-emerges in the direction in which the light first entered.
3. The light emerging from many raindrops creates a rainbow.

Note:
For a more in-dept explanation on how are rainbows formed, you may read click on this to find out more.

This morning, we had 3 groups of HSBC Green Volunteers with us for the walk and I was given the role of Hunter-seeker together with JK who was on his second OJT. Basically our job is to spot marine life and leave markers to inform the groups that there is something worth checking out at the marked spot. =)

As we approached the seagrass area, JK spotted the second 'discovery' (picture below), a ocellated sea cucumber (got this ID from Samson's blog. Thanks, Samson!)
Discovery Note:
1. Another Common name for this is eyed sea cucumber. Look at its appearance for the explanation. =)
2. Sea cucumbers' bodies are able to turn from almost liquid to rock hard because of a tissue found in its body, the ‘catch connective tissue’.

Third 'discovery' was nearby, the common sea star (picture below).
Discovery Note:
1. It also possesses the ‘catch connective tissue’ in its body.
2. With it, the sea star is able to bend its arms for moving around, it can also purposely drop off an arm if it is caught in the arms of a predator.
3. Sea stars also can regenerate lost arms. However, some species may take up to a year to regenerate a lost arm. And if the central disk is damaged, the sea star might die.

As we walked across the seagrass lagoon, JK spotted another kind of sea cucumber (picture below), third 'discovery'!
(Entry@6 June 2007: This is a warty sea cucumber. Thanks to Ron for the ID!)
Discovery Note:
1.The popular Chinese name for sea cucumber is haishen, which means, roughly, ginseng of the sea.
(Entries@6 June 2007: information provided by Ron. Thanks again!)
2. Also called the peanutfish, dragonfish or golden sea cucumber in the sea cucumber trade.
3. They supposedly have an unusual defense mechanism where they can become completely limp and eventually disintegrating all together if taken out of the water for too long. However, if they are not done it too much, they have the ability to reverse this process and recover.

Note:
After some research, i'm not really sure is this a thorned sea cucumber or pineapple sea cucumber or are they the same, would anyone kindly enlighten me on this?

Soon, we headed towards the coral rubble area to look for more things, and soon i chanced upon two sunflower mushroom coral (picture below), fourth 'discovery'!
Note:
The bigger sunflower mushroom coral on the right has a length of about 30cm. That's one of the largest i've seen to date.

And nearby was this short tentacled mushroom coral (picture below) which has a diameter of about 15cm, another big find! Fifth 'discovery'.
Discovery Note:
1. It is named for its oval shape and the radiating skeletal walls (septa) that give this coral its mushroom-like appearance.
2. Mushroom corals do not form colonies like most other corals, each mushroom coral is a single polyp.
3. Unlike most corals, mushroom corals are attached to the reef only when they are small.
4. As larger individuals, they will detach themselves from the reef and live loose on the seafloor.

Sixth 'discovery' was seen, red seaweed (picture below) as i combed the area for the 'highlight' of the walk.
Note:
I might be wrong on this ID, so do correct me if i'm wrong. Thanks.
Discovery Note ('Consumer' info):
1. ‘Nori’ used in Japanese sushi is actually a kind of red seaweed.
2. Red seaweeds provide agar-agar used to make jellies.
3. Red seaweeds are also used to gel and stabilise processed food such as chocolate milk and yogurt.

After exhausting more energy, finally we found the 'highlight' of our trip. The knobbly sea star (picture below)! Seventh 'discovery'.
Discovery Note:
1. Their name comes from the presence of knobs on their topside.
2. Although they are brightly coloured and covered with knobs and spikes, they are not venomous, so you can touch them!

If you looked carefully on the above picture, you would have spotted this knobbly 'junior' (picture below). This looks like the same 'baby' knobbly found by Luan Keng during the last trip. It really looked cute and made us hope that more 'junior' knobbly are around or going to be around, as the knobbly sea star is an endangered species in Singapore due to habitat lost and poachers.
Discovery Note (How do knobbly sea star reproduce?):
1. Sexual reproduction occur when the separate-sexed adults release their eggs and sperm into the waters.
2. Often when one of them spawns, this causes those nearby to also spawn, creating a concentrated mass of eggs and sperm in nearby water, thus increasing the chance of fertilization.

Note: Do correct me if i'm wrong on this.

Eighth 'discovery' was found on the sand found camouflaged on the sand floor. A discodoris nudibranch (picture below). Discovery Note:
1. Nudibranchs are related to snails. Little baby nudibranchs are born with shells, but they lose them when they become adults.
2. Most nudibranchs are carnivores, they eat immobile or small, slow-moving prey. Examples are sponges, ascidians, hard corals, soft corals, sea anemones etc.

Around the inter-tidal area were lots of different patterns of feathery fan worms. Here are two of the ones i've taken photos of (pictures below). Ninth 'discovery'.

Discovery Note:
1. They get their common name from the appearance and structure of their modified tentacles on their head.
2. These modified tentacles are used for feeding. By the way, they do filter feeding.
3. They retract almost instantly into their tubes at the sense of any movement, shadow or danger near them.

Question: What's this?
Guess: Pile of Poo/Shit? Yucks!!!
Conclusion: Tenth 'discovery'.
Discovery Note:
1. This pile of grey coil on the sand bar is called a cast, made by the acorn worm.
2. The worm seldom leaves it’s borrow under the sands, so it is more often we see its cast than the worm itself.

As JK and me headed back towards the shoreline, the different groups were on their way back also as the tide was coming in. Here's Ron with his group crossing the seagrass lagoon (picture below).
Here's Robert leading the way to the planned last stop of the walk, the mangroves of Semakau (picture below).

Even as it got hotter as the sun rose higher in the sky, it didn't seem to melt away the enthusiatic spirit of everyone. Here's Samson's group checking out a species of molluscs, if my memory serves me correct.
After we left the inter-tidal area, everyone either boarded the bus or van. The passengers on the bus were then given a land fill tour by me (again), i'm still trying to master this part of the walk =P

Soon we were brought to the southern most tip of Singapore where the public can access, the southern most tip of Semakau (picture below).

So it was another wonderful walk to Semakau due to the lovely weather and all the interested participants (HSBC Green Volunteers). Not forgetting all the guides too =) Thanks everyone and Semakau, will be back again soon.