Thursday, October 2, 2008

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

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

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

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

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

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:
'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.
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

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

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

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

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