Friday, June 12, 2009

Semakau Inter-Tidal walk on 12 June 2009

Ninety Ninth Discovery Posting:

This morning, I visited Semakau land fill island again with RMBR volunteer guides and participants from various walks of life for another guided walk at the inter tidal area of Semakau.

And like yesterday, the sun greeted us as we walked leisurely towards the forest trail which would bring us to our destination (picture below).
Besides chasing our sleepy moods away, the sunrise also provided us a great photo opportunity (picture below).This scene (picture below) will be the sight and also our destination once one gets through the forest trail. The inter tidal area of Semakau.Today, the group I lead was called Upside down Jellyfish. And here's everyone standing in the seagrass meadow (picture below).
And after crossing the seagrass meadow, our first 'discovery' was marked out by our hardworking hunter seekers, two common sea stars, one on top of another (picture below). Discovery Note:
1. This unique positioning pattern is actually a part of the common sea stars' mating ritual.
2. The male, which is usually smaller in size, will be found on top of the female with its arms alternating with hers.
3. The common sea stars do not external reproduction organs. Therefore this behaviour is to increase the chance of exterior fertilisation.
4. Read more about this and the common sea star @

As the tide today wasn't low enough for us to look at the resident giant clam, we did see the juvenille giant clam around the coral rubble area (picture below). Second 'discovery'.Discovery Note:
They are the largest living bivalve mollusc and also known as the bear's paw clam
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.
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.
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.
5. Read more about them @

Our hunter seekers also managed to find 2 knobbly sea stars today. And this was after some hard work and much walking around (picture below). Kudos to our hunter seekers. =D
Well, we never forget to take a traditional group photo with the knobbly (picture below).Next up, third 'discovery' is the sea slug which most of our visitors use the word 'cute' to describe it. A polka-dot nudibranch (picture below).Discovery Note:
'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.
Nudibranchs are related to snails. Little baby nudibranchs are born with shells, but they lose them when they become adults.
Most nudibranchs are carnivores, they eat immobile or small, slow-moving prey. Examples are sponges, ascidians, hard corals, soft corals, sea anemones etc.
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. Those that eat colourful creatures such as sponges or corals, may themselves be colourful to match their prey. Being small and flat, they can also easily hide in narrow places.
5. Read more about them @

Fourth 'discovery' is another piece of finding from our wonderful hun
ter seekers, a sea horse (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.

Read more about it @

As we headed back, we encoutered this long queue over at the sea grass lagoon. I wonder what was making everyone stop there?
After some simple investiagation, i discovered that they were actually stopping to take a closer look at a spider conch. The fifth 'discovery' of this posting (picture below).Discovery Note:
1. As a result of their really nice shells, spider conches are not only collected for food, they are also collected for their shells.
2. Due to this collection, spider conches have been labelled as a 'vulnerable' on the Red list of threaten animals of Singapore.
3. That aside, the movement of spider conches is quite interesting. They make use of a curved, knifed shaped operculum or in short, a 'leg' or 'pole' to pole vault around.
4. The spikes that are found on the shell helps to prevent the spider conch are rolling around after making a 'hop'.
5. Read more about the spider conch @

Lastly, the sixth 'discovery' is a juvenile cushion star spotted by the participants from KS's group (picture below).
Discovery Note:
1. They are more oftenly seen during diving, so it is always a treat to spot them in the inter-tidal areas.
2. They have been found to feed on some species of hard corals. Their diet could also consist of immobile animals, organic particles found on sediments and sea weeds.
3. Read more about them @

In conclusion, today was another great day out, as the jellyfishes were an attentive and interested group. Thank you, everyone! =D

a) Read KS's posting for this trip:

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